Network Working Group                                     P. Saint-Andre
Internet-Draft                                                 J. Miller
Expires: December 3, 2003                     Jabber Software Foundation
                                                           June 04, 2003


                         XMPP Instant Messaging
                         draft-ietf-xmpp-im-12

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at http://
   www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on December 3, 2003.

Copyright Notice

   Copyright (C) The Internet Society (2003). All Rights Reserved.

Abstract

   This document describes specific extensions to and applications of
   the Extensible Messaging and Presence Protocol (XMPP) that provide
   the basic instant messaging and presence functionality defined in RFC
   2779.











Saint-Andre & Miller    Expires December 3, 2003                [Page 1]


Internet-Draft           XMPP Instant Messaging                June 2003


Table of Contents

   1.    Introduction . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.1   Overview . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.2   Requirements . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.3   Terminology  . . . . . . . . . . . . . . . . . . . . . . . .  4
   1.4   Discussion Venue . . . . . . . . . . . . . . . . . . . . . .  5
   1.5   Intellectual Property Notice . . . . . . . . . . . . . . . .  5
   2.    Establishing a Session . . . . . . . . . . . . . . . . . . .  6
   3.    Exchanging Messages  . . . . . . . . . . . . . . . . . . . .  8
   3.1   Specifying an Intended Recipient . . . . . . . . . . . . . .  8
   3.2   Specifying a Message Type  . . . . . . . . . . . . . . . . .  8
   3.3   Specifying a Message Body  . . . . . . . . . . . . . . . . .  9
   3.4   Specifying a Message Subject . . . . . . . . . . . . . . . . 10
   3.5   Specifying a Conversation Thread . . . . . . . . . . . . . . 10
   4.    Exchanging Presence Information  . . . . . . . . . . . . . . 12
   4.1   Client and Server Responsibilities . . . . . . . . . . . . . 12
   4.2   Specifying Availability Status . . . . . . . . . . . . . . . 14
   4.3   Specifying Detailed Status Information . . . . . . . . . . . 15
   4.4   Specifying Presence Priority . . . . . . . . . . . . . . . . 15
   4.5   Determining When a Contact Went Offline  . . . . . . . . . . 16
   4.6   Presence Examples  . . . . . . . . . . . . . . . . . . . . . 17
   5.    Managing Subscriptions . . . . . . . . . . . . . . . . . . . 22
   5.1   Requesting a Subscription  . . . . . . . . . . . . . . . . . 22
   5.2   Handling a Subscription Request  . . . . . . . . . . . . . . 22
   5.3   Cancelling a Subscription from Another Entity  . . . . . . . 23
   5.4   Unsubscribing from Another Entity's Presence . . . . . . . . 23
   6.    Managing One's Roster  . . . . . . . . . . . . . . . . . . . 24
   6.1   Retrieving One's Roster on Login . . . . . . . . . . . . . . 24
   6.2   Adding a Roster Item . . . . . . . . . . . . . . . . . . . . 25
   6.3   Updating a Roster Item . . . . . . . . . . . . . . . . . . . 26
   6.4   Deleting a Roster Item . . . . . . . . . . . . . . . . . . . 27
   7.    Integration of Roster Items and Presence Subscriptions . . . 28
   7.1   Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 28
   7.2   User Subscribes to Contact . . . . . . . . . . . . . . . . . 28
   7.2.1 Alternate Flow: Contact Declines Subscription Request  . . . 32
   7.3   Creating a Mutual Subscription . . . . . . . . . . . . . . . 33
   7.3.1 Alternate Flow: User Declines Subscription Request . . . . . 36
   7.4   Unsubscribing  . . . . . . . . . . . . . . . . . . . . . . . 37
   7.4.1 Case #1: Unsubscribing When Subscription is Not Mutual . . . 38
   7.4.2 Case #2: Unsubscribing When Subscription is Mutual . . . . . 39
   7.5   Cancelling a Subscription  . . . . . . . . . . . . . . . . . 42
   7.5.1 Case #1: Cancelling When Subscription is Not Mutual  . . . . 42
   7.5.2 Case #2: Cancelling When Subscription is Mutual  . . . . . . 44
   7.6   Removing a Roster Item and Cancelling All Subscriptions  . . 46
   8.    Blocking Communication . . . . . . . . . . . . . . . . . . . 49
   8.1   Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
   8.2   Business Rules . . . . . . . . . . . . . . . . . . . . . . . 51



Saint-Andre & Miller    Expires December 3, 2003                [Page 2]


Internet-Draft           XMPP Instant Messaging                June 2003


   8.3   Retrieving One's Privacy Lists . . . . . . . . . . . . . . . 52
   8.4   Managing Active Lists  . . . . . . . . . . . . . . . . . . . 55
   8.5   Managing the Default List  . . . . . . . . . . . . . . . . . 56
   8.6   Editing a Privacy List . . . . . . . . . . . . . . . . . . . 57
   8.7   Adding a New Privacy List  . . . . . . . . . . . . . . . . . 58
   8.8   Removing a Privacy List  . . . . . . . . . . . . . . . . . . 58
   8.9   Blocking Messages  . . . . . . . . . . . . . . . . . . . . . 59
   8.10  Blocking Inbound Presence Notifications  . . . . . . . . . . 60
   8.11  Blocking Outbound Presence Notifications . . . . . . . . . . 62
   8.12  Blocking IQs . . . . . . . . . . . . . . . . . . . . . . . . 64
   8.13  Blocking All Communication . . . . . . . . . . . . . . . . . 65
   8.14  Blocked Entity Attempts to Communicate with User . . . . . . 67
   8.15  Higher-Level Heuristics  . . . . . . . . . . . . . . . . . . 68
   9.    Server Rules for Handling XML Stanzas  . . . . . . . . . . . 70
   9.1   No 'to' Address  . . . . . . . . . . . . . . . . . . . . . . 70
   9.2   Foreign Domain . . . . . . . . . . . . . . . . . . . . . . . 70
   9.3   Subdomain  . . . . . . . . . . . . . . . . . . . . . . . . . 70
   9.4   Bare Domain or Specific Resource . . . . . . . . . . . . . . 70
   9.5   User in Same Domain  . . . . . . . . . . . . . . . . . . . . 71
   10.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . 73
   10.1  XML Namespace Name for Session Data  . . . . . . . . . . . . 73
   11.   Security Considerations  . . . . . . . . . . . . . . . . . . 74
         Normative References . . . . . . . . . . . . . . . . . . . . 75
         Informative References . . . . . . . . . . . . . . . . . . . 76
         Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 76
   A.    vCards . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
   B.    XML Schemas  . . . . . . . . . . . . . . . . . . . . . . . . 78
   B.1   session  . . . . . . . . . . . . . . . . . . . . . . . . . . 78
   B.2   jabber:iq:last . . . . . . . . . . . . . . . . . . . . . . . 78
   B.3   jabber:iq:privacy  . . . . . . . . . . . . . . . . . . . . . 78
   B.4   jabber:iq:roster . . . . . . . . . . . . . . . . . . . . . . 81
   C.    Revision History . . . . . . . . . . . . . . . . . . . . . . 83
   C.1   Changes from draft-ietf-xmpp-im-11 . . . . . . . . . . . . . 83
   C.2   Changes from draft-ietf-xmpp-im-10 . . . . . . . . . . . . . 83
   C.3   Changes from draft-ietf-xmpp-im-09 . . . . . . . . . . . . . 83
   C.4   Changes from draft-ietf-xmpp-im-08 . . . . . . . . . . . . . 84
   C.5   Changes from draft-ietf-xmpp-im-07 . . . . . . . . . . . . . 84
   C.6   Changes from draft-ietf-xmpp-im-06 . . . . . . . . . . . . . 84
   C.7   Changes from draft-ietf-xmpp-im-05 . . . . . . . . . . . . . 84
   C.8   Changes from draft-ietf-xmpp-im-04 . . . . . . . . . . . . . 85
   C.9   Changes from draft-ietf-xmpp-im-03 . . . . . . . . . . . . . 85
   C.10  Changes from draft-ietf-xmpp-im-02 . . . . . . . . . . . . . 85
   C.11  Changes from draft-ietf-xmpp-im-01 . . . . . . . . . . . . . 85
   C.12  Changes from draft-ietf-xmpp-im-00 . . . . . . . . . . . . . 85
   C.13  Changes from draft-miller-xmpp-im-02 . . . . . . . . . . . . 86
         Intellectual Property and Copyright Statements . . . . . . . 87





Saint-Andre & Miller    Expires December 3, 2003                [Page 3]


Internet-Draft           XMPP Instant Messaging                June 2003


1. Introduction

1.1 Overview

   The core features of the Extensible Messaging and Presence Protocol
   are defined in XMPP Core [1]. These features -- specifically XML
   streams, stream authentication and encryption, and the <message/>,
   <presence/>, and <iq/> children of the stream root -- provide the
   building blocks for many types of near-real-time applications, which
   may be layered on top of the core by sending application-specific
   data qualified by particular XML namespaces. This document describes
   extensions to and applications of XMPP Core that provide the basic
   functionality expected of an instant messaging (IM) and presence
   application as defined in RFC 2779 [2].

1.2 Requirements

   For the purposes of this document, the requirements of a basic
   instant messaging and presence application are defined by RFC 2779
   [2]. At a high level, RFC 2779 stipulates that a user must be able to
   complete the following use cases:

   o  Exchange messages with other users

   o  Exchange presence information with other users

   o  Manage subscriptions to and from other users

   o  Manage items in a contact list (in XMPP this is called a "roster")

   o  Block communications to or from specific other users

   Detailed definitions of these functionality areas are contained in
   RFC 2779, and the interested reader is directed to that document
   regarding the requirements addressed herein.

   Note: while XMPP-based instant messaging and presence meets the
   requirements of RFC 2779, it was not designed explicitly with RFC
   2779 in mind, since the base protocol evolved through an open
   development process within the Jabber open-source community before
   RFC 2779 was written. Note also that although protocols addressing
   many other functionality areas have been defined in the Jabber
   community, such protocols are not included in this document because
   they are not required by RFC 2779 [2].

1.3 Terminology

   This document inherits the terminology defined in XMPP Core [1].



Saint-Andre & Miller    Expires December 3, 2003                [Page 4]


Internet-Draft           XMPP Instant Messaging                June 2003


   The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
   "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [3].

1.4 Discussion Venue

   The authors welcome discussion and comments related to the topics
   presented in this document. The preferred forum is the
   <xmppwg@jabber.org> mailing list, for which archives and subscription
   information are available at <http://www.jabber.org/cgi-bin/mailman/
   listinfo/xmppwg/>.

1.5 Intellectual Property Notice

   This document is in full compliance with all provisions of Section 10
   of RFC 2026. Parts of this specification use the term "jabber" for
   identifying namespaces and other protocol syntax. Jabber[tm] is a
   registered trademark of Jabber, Inc.  Jabber, Inc. grants permission
   to the IETF for use of the Jabber trademark in association with this
   specification and its successors, if any.






























Saint-Andre & Miller    Expires December 3, 2003                [Page 5]


Internet-Draft           XMPP Instant Messaging                June 2003


2. Establishing a Session

   Most instant messaging and presence applications based on XMPP are
   implemented via a client-server architecture that requires a user to
   establish a session on a server in order to engage in the expected
   instant messaging and presence activities. However, there are several
   pre-conditions that must be met before a user may establish such a
   session. These include:

   1.  Account Provisioning -- methods for account provisioning include
       account creation by a server administrator as well as in-band
       account registration using the 'jabber:iq:register' namespace;
       the latter method is documented by the Jabber Software Foundation
       [4] at <http://www.jabber.org/protocol/> but is out of scope for
       this document.

   2.  Authentication and Resource Authorization -- methods for
       completing these pre-conditions are documented in XMPP Core [1];
       note that client authentication with a server MUST include an
       authorization identity that specifies the full JID (<user@domain/
       resource>) associated with the connection for addressing
       purposes.

   Once a client has authenticated with a server and has authorized a
   full JID, it SHOULD request that the server activate an instant
   messaging session for the client. This is accomplished by means of
   the 'urn:ietf:params:xml:ns:xmpp-session' namespace:

   Step 1: Client requests session with server:

   <iq type='set' id='sess_1'>
     <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>
   </iq>

   Step 2: Server informs client that session has been created:

   <iq type='result' id='sess_1'/>

   Several error conditions are possible. For example, the server may
   encounter an internal condition that prevents it from creating the
   session, the username or authorization identity may lack permissions
   to create a session, or there may already be an active session
   associated with an authzid of the same name.

   If the server encounters an internal condition that prevents it from
   creating the session, it MUST return an error.





Saint-Andre & Miller    Expires December 3, 2003                [Page 6]


Internet-Draft           XMPP Instant Messaging                June 2003


   Step 2 (alt): Server responds with error (internal server error):

   <iq type='error' id='sess_1'>
     <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>
     <error type='wait'>
       <internal-server-error
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </iq>

   If the username or authorization identity is not allowed to create a
   session, the server MUST return an error.

   Step 2 (alt): Server responds with error (username or authzid not
   allowed to create session):

   <iq type='error' id='sess_1'>
     <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>
     <error type='auth'>
       <not-allowed
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </iq>

   If there is already an active session associated with an authzid of
   the same name, the server MUST either (1) terminate the active
   session and allow the newly-requested session, or (2) disallow the
   newly-requested session and maintain the existing session. Which of
   these the server does is up to the implementation, although it is
   RECOMMENDED to implement (1).

   Step 2 (alt): Server informs client of resource conflict (the desired
   resource name is already in use by another active connection):

   <iq type='error' id='sess_1'>
     <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>
     <error type='cancel'>
       <conflict
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </iq>

   After establishing a session, a client SHOULD send initial presence
   and request its roster as described below, although these actions are
   NOT REQUIRED.






Saint-Andre & Miller    Expires December 3, 2003                [Page 7]


Internet-Draft           XMPP Instant Messaging                June 2003


3. Exchanging Messages

   Exchanging messages is a basic use of XMPP and is effected when a
   user generates a message stanza that is addressed to another user
   (or, more generally, another entity). As defined under Section 9, the
   sender's server is responsible for delivering the message to the
   intended recipient (if the recipient is on the same server) or for
   routing the message to the recipient's server (if the recipient is on
   a different server).

   For information regarding the syntax of message stanzas as well as
   their defined attributes and child elements, refer to XMPP Core [1].

3.1 Specifying an Intended Recipient

   An instant messaging client SHOULD specify an intended recipient for
   a message by providing the JID of an entity other than the sender in
   the 'to' attribute of the <message/> stanza. If the message is being
   sent in reply to a message previously received from an address of the
   form <user@domain/resource> (e.g., within the context of a chat
   session), the value of the 'to' address SHOULD be the full JID
   (<user@domain/resource>) rather than merely <user@domain> unless the
   sender has knowledge (via presence) that the intended recipient's
   resource is no longer available. If the message is being sent outside
   the context of any existing chat session or received message, the
   value of the 'to' address SHOULD be of the form <user@domain> rather
   than <user@domain/resource>.

3.2 Specifying a Message Type

   As mentioned in XMPP Core [1], there are several defined types of
   messages (specified by means of a 'type' attribute within the
   <message/> element). In the context of an instant messaging
   application, a client SHOULD include a message type in order to
   capture the conversational context of the message, thus providing a
   hint regarding presentation (e.g., in a GUI). If the 'type' attribute
   is included, it SHOULD have one of the following values (any other
   value MAY be ignored):

   o  chat -- The message is sent in the context of a one-to-one chat
      conversation. A compliant client SHOULD present an interface
      enabling one-to-one chat between the two parties, including an
      appropriate conversation history.

   o  error -- An error has occurred related to a previous message sent
      by the sender (for details regarding stanza error syntax, see XMPP
      Core [1]). A compliant client SHOULD present an appropriate
      interface informing the sender of the nature of the error.



Saint-Andre & Miller    Expires December 3, 2003                [Page 8]


Internet-Draft           XMPP Instant Messaging                June 2003


   o  groupchat -- The message is sent in the context of a multi-user
      chat environment. A compliant client SHOULD present an interface
      enabling many-to-many chat between the parties, including a roster
      of parties in the chatroom and an appropriate conversation
      history.

   o  headline -- The message is probably generated by an automated
      service that delivers or broadcasts content (news, sports, market
      information, RSS feeds, etc.). No reply to the message is
      expected, and a compliant client SHOULD present an interface that
      appropriately differentiates the message from standalone messages,
      chat sessions, or groupchat sessions (e.g., by not providing the
      recipient with the ability to reply).

   o  normal -- The message is a standalone message to which the
      recipient MAY reply if desired. This is the default type; if no
      'type' attribute is provided, or if the value of the 'type'
      attribute is other than one of the values specified, an
      application SHOULD consider the message to be of type "normal".

   Although the 'type' attribute is NOT REQUIRED, it is considered
   polite to mirror the type in any replies to a message; furthermore,
   some specialized applications (e.g., a multi-user chat service) MAY
   at their discretion enforce the use of a particular message type
   (e.g., type='groupchat').

3.3 Specifying a Message Body

   A message stanza MAY (and often will) contain a child <body/> element
   specifying the primary meaning of the message. The content of the
   body element MUST be XML character data and the element MUST NOT
   contain mixed content. If it is necessary to provide the primary
   meaning in an alternate form (e.g., formatted using XHTML), the
   alternate form MUST be contained in some other child of the message
   stanza. However, multiple <body/> elements MAY be included to provide
   the primary meaning in different languages, as long as each such
   element possesses an 'xml:lang' attribute with a distinct value.

   Example: A message with a body:

   <message
       to='romeo@montague.net'
       from='juliet@capulet.com/balcony'
       xml:lang='en'>
     <body>Wherefore art thou, Romeo?</body>
     <body xml:lang='cz'>Pro&#x010D;e&#x017D; jsi ty, Romeo?</body>
   </message>




Saint-Andre & Miller    Expires December 3, 2003                [Page 9]


Internet-Draft           XMPP Instant Messaging                June 2003


3.4 Specifying a Message Subject

   A message stanza MAY contain one or more child <subject/> elements
   specifying the topic of the message. The content of the subject
   element MUST be XML character data and the element MUST NOT contain
   mixed content. Multiple <subject/> elements MAY be included, as long
   as each such element possesses an 'xml:lang' attribute with a
   distinct value.

   Example: A message with a subject:

   <message
       to='romeo@montague.net'
       from='juliet@capulet.com/balcony'
       xml:lang='en'>
     <subject>I implore you!</subject>
     <subject xml:lang='cz'>
       &#x00DA;p&#x011B;nliv&#x011B; prosim!
     </subject>
     <body>Wherefore art thou, Romeo?</body>
     <body xml:lang='cz'>
       Pro&#x010D;e&#x017D; jsi ty, Romeo?
     </body>
   </message>


3.5 Specifying a Conversation Thread

   A message stanza MAY contain a child <thread/> element specifying the
   conversation thread in which the message is situated, for the purpose
   of tracking the conversation. The content of the <thread/> element is
   a random string that is generated by the sender in accordance with
   the algorithm specified in XMPP Core [1]; this string SHOULD be
   copied back to the sender in subsequent replies.

















Saint-Andre & Miller    Expires December 3, 2003               [Page 10]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: A threaded conversation:

   <message
       to='romeo@montague.net/orchard'
       from='juliet@capulet.com/balcony'
       type='chat'>
     <body>Art thou not Romeo, and a Montague?</body>
     <thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
   </message>

   <message
       to='juliet@capulet.com/balcony'
       from='romeo@montague.net/orchard'
       type='chat'>
     <body>Neither, fair saint, if either thee dislike.</body>
     <thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
   </message>

   <message
       to='romeo@montague.net/orchard'
       from='juliet@capulet.com/balcony'
       type='chat'>
     <body>How cam'st thou hither, tell me, and wherefore?</body>
     <thread>e0ffe42b28561960c6b12b944a092794b9683a38</thread>
   </message>


























Saint-Andre & Miller    Expires December 3, 2003               [Page 11]


Internet-Draft           XMPP Instant Messaging                June 2003


4. Exchanging Presence Information

   Exchanging presence information is made relatively straightforward
   within XMPP by using presence stanzas. However, we see here a
   contrast to the handling of messages: although a client MAY send
   directed presence information to another entity, normally presence
   information is sent from a client to its server (with no 'to'
   address) and then broadcasted by the server to any entities that are
   subscribed to the presence of the sending entity. (Note: in the
   terminology of RFC 2778 [5], the only watchers in XMPP are
   subscribers.)

   For information regarding the syntax of presence stanzas as well as
   their defined attributes and child elements, refer to XMPP Core [1].

4.1 Client and Server Responsibilities

   When a client connects to its server, it SHOULD (but is NOT REQUIRED
   to) send initial presence to the server in order to signal its
   availability for communications. As defined herein, the initial
   presence stanza (1) MUST possess no 'to' address (signalling that it
   is meant to be handled by the server on behalf of the user) and (2)
   MUST possess no 'type' attribute (signalling the user's
   availability).

   Upon receiving initial presence from a client, the user's server MUST
   do the following:

   1.  Send presence probes (i.e., presence stanzas whose 'type'
       attribute is set to a value of "probe") from the full JID
       (<user@domain/resource>) of the user to the bare JID
       (<user@domain>) of any contacts to which the user is subscribed
       in order to determine if they are available; such contacts are
       those which are present in the user's roster with the
       'subscription' attribute set to a value of "to" or "both". (Note:
       a user or client SHOULD NOT send presence probes.)

   2.  Broadcast initial presence from the full JID (<user@domain/
       resource>) of the user to the bare JID (<user@domain>) of any
       contacts that are subscribed to the user's presence; such
       contacts are those which are present in the user's roster with
       the 'subscription' attribute set to a value of "from" or "both".

   Upon receiving a presence probe from the user, the contact's server
   MUST send to the user the last known availability information (i.e.,
   the full XML of the last presence stanza) provided by each of the
   contact's active sessions (if there exist no active sessions, the
   server SHOULD NOT reply to the presence probe). The server MUST send



Saint-Andre & Miller    Expires December 3, 2003               [Page 12]


Internet-Draft           XMPP Instant Messaging                June 2003


   this information subject to domain-specific access rules, and only if
   the user is in the contact's roster with a subscription state of
   "from" or "both" and the contact has not blocked outbound presence
   notifications to the user's bare or full JID (as defined in Section
   8.11). (Note: if the server receives a presence probe from a
   subdomain of the server's hostname or another such trusted service,
   it MAY provide presence information about the user to that entity.)

   Upon receiving initial presence from the user, the contact's server
   MUST deliver the user's presence stanza to the full JIDs
   (<contact@domain/resource>) associated with all of the contact's
   active sessions, but only if the user is in the contact's roster with
   a subscription state of "to" or "both" and the contact has not
   blocked inbound presence notifications from the user's bare or full
   JID (as defined in Section 8.10).

   If the user's server receives a presence stanza of type "error" in
   response to the initial presence that it forwarded to a contact on
   behalf of the user, it MUST NOT send further presence updates to that
   contact (until and unless it receives a presence probe from the
   contact).

   After sending initial presence, the user MAY update and broadcast its
   presence information at any time during its active session by sending
   a presence stanza with no 'to' address and either no 'type' attribute
   or a 'type' attribute with a value of "unavailable". (Note: a user's
   client SHOULD NOT send a presence update to broadcast information
   that changes independently of the user's presence and availability.)
   If the presence stanza lacks a 'type' attribute (i.e., expresses
   availability), the user's server MUST broadcast the full XML of that
   presence stanza to all contacts (1) that are in the user's roster
   with a subscription type of "from" or "both", (2) to whom the user
   has not blocked outbound presence, and (3) from whom the server has
   not received a presence error during the user's session. If the
   presence stanza has a 'type' attribute set to a value of
   "unavailable", the user's server MUST broadcast the full XML of that
   presence stanza to all contacts meeting the three conditions just
   mentioned, as well as to any entities to which the user has sent
   directed available presence during the user's session (if the user
   has not yet sent directed unavailable presence to that entity).

   A user MAY send directed presence to another entity (i.e., a presence
   stanza with a 'to' attribute whose value is the JID of the other
   entity and with either no 'type' attribute or a 'type' attribute
   whose value is "unavailable"). There are three possible cases:

   1.  If the user sends directed presence to a contact that is in the
       user's roster with a subscription type of "from" or "both" after



Saint-Andre & Miller    Expires December 3, 2003               [Page 13]


Internet-Draft           XMPP Instant Messaging                June 2003


       having sent initial presence and before sending unavailable
       presence broadcast, the user's server MUST route or deliver the
       full XML of that presence stanza (subject to privacy rules) but
       SHOULD NOT otherwise modify the contact's status regarding
       presence broadcast (i.e., it SHOULD include the contact's JID in
       any subsequent presence broadcasts initiated by the user).

   2.  If the user sends directed presence to an entity that is not in
       the user's roster with a subscription type of "from" or "both"
       after having sent initial presence and before sending unavailable
       presence broadcast, the user's server MUST route or deliver the
       full XML of that presence stanza to the entity but MUST NOT
       modify the contact's status regarding available presence
       broadcast (i.e., it MUST NOT include the entity's JID in any
       subsequent broadcasts of available presence initiated by the
       user); however, if the connected resource from which the user
       sent the directed presence become unavailable, the user's server
       MUST broadcast that unavailable presence to the entity (if the
       user has not yet sent directed unavailable presence to that
       entity).

   3.  If the user sends directed presence without ever first sending
       initial presence or after having sent unavailable presence
       broadcast, the user's server MUST treat the entities to which the
       user sends directed presence in the same way that it treats the
       entities listed in Case 2 above.

   Before ending its session with a server, a client SHOULD gracefully
   become unavailable by sending a final presence stanza that possesses
   no 'to' attribute and that possesses a 'type' attribute whose value
   is "unavailable" (optionally, the final presence stanza MAY contain
   one or more <status/> elements specifying the reason why the user is
   no longer available). However, the user's server MUST NOT depend on
   receiving final presence from an available resource, since the
   resource may become unavailable unexpectedly. If the user's server
   detects that one of the user's resources has become unavailable for
   any reason (either gracefully or ungracefully), it MUST broadcast
   unavailable presence to all contacts (1) that are in the user's
   roster with a subscription type of "from" or "both", (2) to whom the
   user has not blocked outbound presence, and (3) from whom the server
   has not received a presence error during the user's session; the
   user's server MUST also send that unavailable presence stanza to any
   entities to which the user has sent directed presence during the
   user's session for that resource (if the user has not yet sent
   directed unavailable presence to that entity).

4.2 Specifying Availability Status




Saint-Andre & Miller    Expires December 3, 2003               [Page 14]


Internet-Draft           XMPP Instant Messaging                June 2003


   A client MAY provide further information about its availability
   status by using the <show/> element. As mentioned in XMPP Core [1],
   the recognized values for the show element are:

   o  away -- The entity or resource is temporarily away.

   o  chat -- The entity or resource is actively interested in chatting.

   o  xa -- The entity or resource is away for an extended period (xa =
      "eXtended Away").

   o  dnd -- The entity or resource is busy (dnd = "Do Not Disturb").

   Example: Availability status:

   <presence>
     <show>dnd</show>
   </presence>

   If no <show/> element is provided, the entity is assumed to be online
   and available.

4.3 Specifying Detailed Status Information

   In conjunction with the  <show/> element, a client MAY provide
   detailed status information by using the <status/> element. The
   content of this element is a natural-language description of the
   user's current availability status. The content of the status element
   MUST be XML character data and the element MUST NOT contain mixed
   content. Multiple <status/> elements MAY be included, as long as each
   such element possesses an 'xml:lang' attribute with a distinct value.

   Example: Detailed status information:

   <presence xml:lang='en'>
     <show>dnd</show>
     <status>Wooing Juliet</status>
     <status xml:lang='cz'>Ja dvo&#x0159;&#x00ED;m Juliet</status>
   </presence>


4.4 Specifying Presence Priority

   A client MAY provide a priority for its resource by using the
   <priority/> element. The content of this element is an integer whose
   value is between -128 and +127. If a client does not provide the
   priority element in a presence stanza, its server SHOULD assume that
   the priority value is zero.



Saint-Andre & Miller    Expires December 3, 2003               [Page 15]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Presence priority:

   <presence xml:lang='en'>
     <show>dnd</show>
     <status>Wooing Juliet</status>
     <status xml:lang='cz'>Ja dvo&#x0159;&#x00ED;m Juliet</status>
     <priority>1</priority>
   </presence>


4.5 Determining When a Contact Went Offline

   The server MUST maintain a record of the time at which a user became
   unavailable (whether gracefully or ungracefully). An authorized
   subscriber to that user's presence MAY request the time of last
   activity by sending an IQ stanza to the user's bare JID
   (<user@domain>) containing an empty <query/> element qualified by the
   'jabber:iq:last' namespace:

   Example: Requesting the last active time of an offline user:

   <iq type='get' to='user@domain'>
     <query xmlns='jabber:iq:last'/>
   </iq>

   If the entity requesting the time of last activity is an authorized
   subscriber to the user's presence (i.e., exists in the user's roster
   with the 'subscription' attribute set to a value of "from" or "both")
   and the user is not blocking IQ stanzas to and from the entity (as
   defined in Section 8.12), the server SHOULD return an IQ stanza of
   type "result" with the number of seconds since the user was last
   active:

   Example: Returning the last active time of an offline user:

   <iq from='user@domain' type='result' to='subscriber@domain/resource'>
     <query seconds='76490' xmlns='jabber:iq:last'/>
   </iq>

   If the entity requesting the time of last activity is not an
   authorized subscriber to the user's presence (i.e., does not exist in
   the user's roster with the 'subscription' attribute set to a value of
   "from" or "both"), the server MUST return an IQ stanza of type
   "error" with an error condition of forbidden:







Saint-Andre & Miller    Expires December 3, 2003               [Page 16]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Requester is forbidden to view the last active time of an
   offline user:

   <iq from='user@domain' type='error' to='subscriber@domain/resource'>
     <query xmlns='jabber:iq:last'/>
     <error type='auth'>
       <forbidden
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </iq>

   Note: this document defines responses to requests for last active
   time only with regard to JIDs of the form <user@domain>, and only
   with regard to JIDs that correspond to an (offline) instant messaging
   user. The behavior of other JID forms (e.g., <user@domain/resource>
   or <domain>) and entity types (e.g., online user or host) is out of
   scope and undefined.

4.6 Presence Examples

   The examples in this section illustrate the presence-related
   protocols described above. The user is romeo@montague.net, he has
   authorized a resource "orchard", and he has the following individuals
   in his roster:

   o  juliet@capulet (subscription="both" and she has two active
      sessions, one whose resource is "chamber" and another whose
      resource is "balcony")

   o  benvolio@shakespeare.lit (subscription="to")

   o  mercutio@verona.it (subscription="from")

   Example 1: User sends initial presence:

   <presence/>















Saint-Andre & Miller    Expires December 3, 2003               [Page 17]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example 2: User's server sends presence probe to contacts with
   subscription="to" and subscription="both" on behalf of the user's
   connected resource:

   <presence
       type='probe'
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com'/>

   <presence
       type='probe'
       from='romeo@montague.net/orchard'
       to='benvolio@shakespeare.lit'/>

   Example 3: User's server sends initial presence to contacts with
   subscription="from" and subscription="both" on behalf of the user's
   connected resource:

   <presence
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com'/>

   <presence
       from='romeo@montague.net/orchard'
       to='mercutio@verona.it'/>


























Saint-Andre & Miller    Expires December 3, 2003               [Page 18]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example 4: Contacts' server replies to presence probe on behalf of
   all of the contact's available resources:

   <presence
       from='juliet@capulet.com/balcony'
       to='romeo@montague.net/orchard'
       xml:lang='en'>
     <show>away</show>
     <status>be right back</status>
     <priority>0</priority>
   </presence>

   <presence
       from='juliet@capulet.com/chamber'
       to='romeo@montague.net/orchard'>
     <priority>1</priority>
   </presence>

   <presence
       from='benvolio@shakespeare.lit/pda'
       to='romeo@montague.net/orchard'
       xml:lang='en'>
     <show>dnd</show>
     <status>gallivanting</status>
   </presence>

   Example 5: Contact's server delivers user's initial presence to all
   of the contact's available resources or returns error to user:

   <presence
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com/chamber'/>

   <presence
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com/balcony'/>

   <presence
       type='error'
       from='mercutio@verona.it'
       to='romeo@montague.net/orchard'>
     <error type='cancel'>
       <remote-server-not-found
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </presence>





Saint-Andre & Miller    Expires December 3, 2003               [Page 19]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example 6: User sends directed presence to another user not in his
   roster:

   <presence
       from='romeo@montague.net/orchard'
       to='nurse@capulet.com'
       xml:lang='en'>
     <show>dnd</show>
     <status>courting Juliet</status>
     <priority>0</priority>
   </presence>

   Example 7: User sends updated available presence information for
   broadcasting:

   <presence xml:lang='en'>
     <show>away</show>
     <status>I shall return!</status>
     <priority>1</priority>
   </presence>

   Example 8: Updated presence information is delivered only to one
   contact (not those from whom an error was received or to whom the
   user sent directed presence):

   <presence
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com/chamber'
       xml:lang='en'>
     <show>away</show>
     <status>I shall return!</status>
     <priority>1</priority>
   </presence>

   <presence
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com/balcony'
       xml:lang='en'>
     <show>away</show>
     <status>I shall return!</status>
     <priority>1</priority>
   </presence>

   Example 9: One of the contact's resources sends final presence:

   <presence type='unavailable'/>





Saint-Andre & Miller    Expires December 3, 2003               [Page 20]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example 10: Contact's server sends unavailable presence information
   to user:

   <presence
       type='unavailable'
       from='juliet@capulet.com/balcony'
       to='romeo@montague.net/orchard'/>

   Example 11: User sends final presence:

   <presence type='unavailable' xml:lang='en'>
     <status>gone home</status>
   </presence>

   Example 12: Unavailable presence information is delivered to
   contact's one remaining resource as well as to the person to whom the
   user sent directed presence:

   <presence
       type='unavailable'
       from='romeo@montague.net/orchard'
       to='juliet@capulet.com/chamber'
       xml:lang='en'>
     <status>gone home</status>
   </presence>

   <presence
       from='romeo@montague.net/orchard'
       to='nurse@capulet.com'
       xml:lang='en'>
     <status>gone home</status>
   </presence>



















Saint-Andre & Miller    Expires December 3, 2003               [Page 21]


Internet-Draft           XMPP Instant Messaging                June 2003


5. Managing Subscriptions

   In order to protect the privacy of instant messaging users and any
   other entities, presence and availability information is disclosed
   only to other entities that the user has approved. When a user has
   agreed that another entity may view its presence, the entity is said
   to have a subscription to the user's presence information. A
   subscription lasts across sessions; indeed, it lasts until the
   subscriber unsubscribes or the subscribee cancels the
   previously-granted subscription. Subscriptions are managed within
   XMPP by sending presence stanzas containing specially-defined
   attributes.

   Note: there are important interactions between subscriptions and
   rosters; these are defined under Integration of Roster Items and
   Presence Subscriptions (Section 7), and the reader must refer to that
   section for a complete understanding of presence subscriptions.

5.1 Requesting a Subscription

   A request to subscribe to another entity's presence is made by
   sending a presence stanza of type "subscribe".

   Example: Sending a subscription request:

   <presence to='juliet@capulet.com' type='subscribe'/>

   If the subscription request is being sent to another instant
   messaging user, the JID supplied in the 'to' attribute SHOULD be of
   the form <user@domain> rather than <user@domain/resource>.

   A user's server MUST NOT automatically accept subscription requests
   on the user's behalf. All subscription requests MUST be directed to
   the user's client. If there is no available resource associated with
   the user when the subscription request is received by the server, the
   user's server MUST store the subscription request offline for
   delivery when the user next becomes available. (Note: if a resource
   has authorized a session but has not provided initial presence, the
   server SHOULD NOT consider it to be available and therefore SHOULD
   NOT send subscription requests to it.)

5.2 Handling a Subscription Request

   When a client receives a subscription request from another entity, it
   MUST either accept the request by sending a presence stanza of type
   "subscribed" or decline the request by sending a presence stanza of
   type "unsubscribed".




Saint-Andre & Miller    Expires December 3, 2003               [Page 22]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Accepting a subscription request:

   <presence to='romeo@montague.net' type='subscribed'/>

   Example: Denying a presence subscription request:

   <presence to='romeo@montague.net' type='unsubscribed'/>


5.3 Cancelling a Subscription from Another Entity

   If a user would like to cancel a previously-granted subscription
   request, it sends a presence stanza of type "unsubscribed".

   Example: Cancelling a previously granted subscription request:

   <presence to='romeo@montague.net' type='unsubscribed'/>


5.4 Unsubscribing from Another Entity's Presence

   If a user would like to unsubscribe from the presence of another
   entity, it sends a presence stanza of type "unsubscribe".

   Example: Unsubscribing from an entity's presence:

   <presence to='juliet@capulet.com' type='unsubscribe'/>
























Saint-Andre & Miller    Expires December 3, 2003               [Page 23]


Internet-Draft           XMPP Instant Messaging                June 2003


6. Managing One's Roster

   In XMPP, one's contact list is called a roster, which consists of any
   number of specific roster items, each roster item being identified by
   a unique JID (usually of the form <contact@domain>). A user's roster
   is stored by the user's server on the user's behalf so that the user
   may access roster information from any available resource.

   Note: there are important interactions between rosters and
   subscriptions; these are defined under Integration of Roster Items
   and Presence Subscriptions (Section 7), and the reader must refer to
   that section for a complete understanding of roster management.

6.1 Retrieving One's Roster on Login

   Upon connecting to the server, a client SHOULD request the roster
   (however, because receiving the roster may not be desirable for all
   resources, e.g., a connection with limited bandwidth, the client's
   request for the roster is NOT REQUIRED). If an available resource
   does not request the roster during a session, the server SHOULD NOT
   send it presence subscriptions and associated "roster pushes".

   Example: Client requests current roster from server:

   <iq type='get' id='roster_1'>
     <query xmlns='jabber:iq:roster'/>
   </iq>
























Saint-Andre & Miller    Expires December 3, 2003               [Page 24]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Client receives roster from the server:

   <iq id='roster_1' type='result'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='romeo@montague.net'
           name='Romeo'
           subscription='both'>
         <group>Friends</group>
       </item>
       <item
           jid='mercutio@verona.it'
           name='Mercutio'
           subscription='both'>
         <group>Friends</group>
       </item>
       <item
           jid='benvolio@shakespeare.lit'
           name='Benvolio'
           subscription='both'>
         <group>Friends</group>
       </item>
     </query>
   </iq>


6.2 Adding a Roster Item

   At any time, a user MAY add an item to his or her roster.

   Example: Client adds a new item:

   <iq type='set' id='roster_2'>
     <query xmlns='jabber:iq:roster'>
       <item
           name='Nurse'
           jid='nurse@capulet.com'>
         <group>Servants</group>
       </item>
     </query>
   </iq>

   The value of the 'jid' attribute SHOULD be of the form <user@domain>,
   especially if the item is associated with another (human) instant
   messaging user.

   The server MUST update the roster information in persistent storage,
   and also push the change out to all of the user's available resources



Saint-Andre & Miller    Expires December 3, 2003               [Page 25]


Internet-Draft           XMPP Instant Messaging                June 2003


   that have requested the roster. This "roster push" consists of an IQ
   set from the server to the client and enables all available resources
   to remain in sync with the server-based roster information.

   Example: Server (1) pushes the updated roster information to all
   available resources and (2) replies with an IQ result to the sending
   resource:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           name='Nurse'
           jid='nurse@capulet.com'
           subscription='none'>
         <group>Servants</group>
       </item>
     </query>
   </iq>

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           name='Nurse'
           jid='nurse@capulet.com'
           subscription='none'>
         <group>Servants</group>
       </item>
     </query>
   </iq>

   <iq type='result' id='roster_2'/>

   Example: Connected resources reply with an IQ result to the server:

   <iq
       from='juliet@capulet.com/balcony'
       to='capulet.com'
       type='result'/>
   <iq
       from='juliet@capulet.com/chamber'
       to='capulet.com'
       type='result'/>


6.3 Updating a Roster Item

   Updating an existing roster item (e.g., changing the group) is done
   in the same way as adding a new roster item, i.e., by sending the



Saint-Andre & Miller    Expires December 3, 2003               [Page 26]


Internet-Draft           XMPP Instant Messaging                June 2003


   roster item in an IQ set to the server.

   Example: User updates roster item (added group):

   <iq type='set' id='roster_3'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='romeo@montague.net'
           name='Romeo'
           subscription='both'>
         <group>Friends</group>
         <group>Lovers</group>
       </item>
     </query>
   </iq>

   As with adding a roster item, when updating a roster item the server
   MUST update the roster information in persistent storage, and also
   initiate a "roster push" to all of the user's available resources
   that have requested the roster.

6.4 Deleting a Roster Item

   At any time, a user MAY delete an item from its roster by doing an IQ
   set and making sure that the value of the 'subscription' attribute is
   "remove" (a compliant server MUST ignore any other values of the
   'subscription' attribute when received from a client).

   Example: Client removes an item:

   <iq type='set' id='roster_4'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='nurse@capulet.com'
           subscription='remove'/>
     </query>
   </iq>

   As with adding a roster item, when deleting a roster item the server
   MUST update the roster information in persistent storage, initiate a
   "roster push" to all of the user's available resources that have
   requested the roster (with the 'subscription' attribute set to a
   value of "remove"), and send an IQ result to the initiating resource.

   For further information about the implications of this command, see
   Section 7.6.





Saint-Andre & Miller    Expires December 3, 2003               [Page 27]


Internet-Draft           XMPP Instant Messaging                June 2003


7. Integration of Roster Items and Presence Subscriptions

7.1 Overview

   Some level of integration between roster items and presence
   subscriptions is normally expected by an instant messaging user
   regarding the user's subscriptions to and from other contacts. This
   section describes the level of integration that must be supported
   within XMPP IM.

   There are four primary subscription states:

   o  None -- Neither the user nor the contact is subscribed to the
      other's presence

   o  To -- The user is subscribed to the contact's presence but there
      is no subscription from the contact to the user

   o  From -- There is a subscription from the contact to the user, but
      the user has not subscribed to the contact's presence

   o  Both -- Both the user and the contact are subscribed to each
      other's presence (i.e., the union of 'from' and 'to')

   Each of these states is reflected in the roster of both the user and
   the contact, thus resulting in durable subscription states. A
   detailed explanation of how these subscription states interact with
   roster items is provided in the following sub-sections.

   If a connected resource does not both send initial presence and
   request the roster, the server SHOULD NOT send it presence
   subscription requests or "roster pushes".

   The 'from' and 'to' addresess are OPTIONAL in roster pushes; if
   included, their values SHOULD be the full JID of the resource for
   that session. A client MUST acknowledge each "roster push" with an IQ
   stanza of type "result" (for the sake of brevity, these stanzas are
   not shown in the following examples but are required by XMPP Core
   [1]).

7.2 User Subscribes to Contact

   The process by which a user subscribes to a contact, including the
   interaction between roster items and subscription states, is defined
   below.

   1.  In preparation for being able to render the contact in the user's
       client interface and for the server to keep track of the



Saint-Andre & Miller    Expires December 3, 2003               [Page 28]


Internet-Draft           XMPP Instant Messaging                June 2003


       subscription, the user's client SHOULD perform a "roster set" for
       the new roster item. This request consists of an IQ stanza of
       type='set' containing a <query/> element in the
       'jabber:iq:roster' namespace, which in turn contains an <item/>
       element that defines the new roster item; the <item/> element
       MUST possess a 'jid' attribute, MAY possess a 'name' attribute,
       MUST NOT possess a 'subscription' attribute, and MAY contain one
       or more <group/> child elements:

   <iq type='set' id='int1'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   2.  As a result, the user's server (1) MUST initiate a "roster push"
       for the new roster item to all available resources associated
       with this user that have requested the roster, setting the
       'subscription' attribute to a value of "none"; and (2) MUST reply
       with an IQ stanza of type='result':

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='none'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <iq type='result' id='int1'/>

   3.  If the user wants to request a subscription to the contact's
       presence, the user's client MUST send a presence stanza of
       type='subscribe' to the contact:

   <presence to='contact@domain' type='subscribe'/>

   4.  As a result, the user's server MUST initiate a second "roster
       push" to all of the user's available resources that have
       requested the roster, setting the contact to the pending
       sub-state of the 'none' subscription state; this pending



Saint-Andre & Miller    Expires December 3, 2003               [Page 29]


Internet-Draft           XMPP Instant Messaging                June 2003


       sub-state is denoted by the inclusion of the ask='subscribe'
       attribute in the roster item:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='none'
           ask='subscribe'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

       Note: if the user did not create a roster item before sending the
       subscription request, the server MUST now create one and send a
       "roster push" to all of the user's available resources that have
       requested the roster, absent the 'name' attribute and the <group/
       > child.

   5.  The user's server MUST also stamp the presence stanza of type
       "subscribe" with the user's bare JID (i.e., <user@domain>) as the
       'from' address. If the contact is served by a different host than
       the user, the user's server MUST route the presence stanza to the
       contact's server for delivery to the contact (this case is
       assumed throughout; however, if the contact is served by the same
       host, then the server can simply deliver the presence stanza
       directly):

   <presence
       from='user@domain'
       to='contact@domain'
       type='subscribe'/>

   6.  Upon receiving the presence stanza of type "subscribe" addressed
       to the contact, the contact's server must determine if there is
       at least one active session in which the contact has sent
       available presence and has requested the roster. If so, it MUST
       deliver the subscription request to the contact (if not, the
       contact's server MUST store the subscription request offline for
       delivery when this condition is next met). No matter when the
       subscription request is delivered, the contact must decide
       whether or not to accept it (subject to configured preferences,
       the contact's client MAY accept or deny the subscription request
       without presenting it to the contact). Here we assume the "happy
       path" that the contact accepts the subscription request (the
       alternate flow of declining the subscription request is defined



Saint-Andre & Miller    Expires December 3, 2003               [Page 30]


Internet-Draft           XMPP Instant Messaging                June 2003


       in Section 7.2.1). In this case, the contact's client (1) SHOULD
       perform a roster set specifying the desired nickname and group
       for the user; and (2) MUST send a presence stanza of type
       "subscribed" to the user in order to accept the subscription
       request.

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence to='user@domain' type='subscribed'/>

   7.  As a result, the contact's server (1) MUST initiate a "roster
       push" to all available resources associated with the contact that
       have requested the roster, containing a roster item for the user
       with the subscription state set to 'from'; (2) MUST route the
       presence stanza of type "subscribed" to the user; and (3) MUST
       send available presence from all of the contact's available
       resources to the user:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='from'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       from='contact@domain/resource'
       to='user@domain'
       type='subscribed'/>

   <presence
       from='contact@domain/resource'
       to='user@domain'/>

   8.  Upon receiving the presence stanza of type "subscribed" addressed
       to the user, the user's server MUST first verify that the contact



Saint-Andre & Miller    Expires December 3, 2003               [Page 31]


Internet-Draft           XMPP Instant Messaging                June 2003


       is in the user's roster with either of the following states: (a)
       subscription='none', ask='subscribe' or (b) subscription='from',
       ask='subscribe'. If the contact is not in the user's roster with
       either of those states, the user's server MUST silently ignore
       the presence stanza of type "subscribed" (i.e., it MUST NOT route
       it to the user, modify the user's roster, or generate a roster
       push to the user's available resources). If the contact is in the
       user's roster with either of those states, the user's server (1)
       MUST deliver the presence stanza of type "subscribed" from the
       contact to the user; (2) MUST initiate a "roster push" to all of
       the user's available resources that have requested the roster,
       containing an updated roster item for the contact with the
       'subscription' attribute set to a value of "to"; and (3) MUST
       deliver the available presence stanza received from each of the
       contact's available resources to each of the user's available
       resources:

   <presence
       to='user@domain'
       from='contact@domain'
       type='subscribed'/>

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='to'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <presence
       from='contact@domain/resource'
       to='user@domain/resource'/>

   From the perspective of the user, there now exists a subscription to
   the contact; from the perspective of the contact, there now exists a
   subscription from the user. (Note: If at this point the user sends
   another subscription request to the contact, the user's server MUST
   silently ignore that request.)

7.2.1 Alternate Flow: Contact Declines Subscription Request

   The above activity flow represents the "happy path" related to the
   user's subscription request to the contact. The main alternate flow
   occurs if the contact denies the user's subscription request.



Saint-Andre & Miller    Expires December 3, 2003               [Page 32]


Internet-Draft           XMPP Instant Messaging                June 2003


   1.  If the contact wants to deny the request, the contact's client
       MUST send a presence stanza of type "unsubscribed" to the user
       (instead of the presence stanza of type "subscribed" sent in Step
       6 of Section 7.2):

   <presence to='user@domain' type='unsubscribed'/>

   2.  As a result, the contact's server MUST route the presence stanza
       of type "unsubscribed" to the user, first stamping the 'from'
       address as the bare JID (<contact@domain>) of the contact:

   <presence
       from='contact@domain'
       to='user@domain'
       type='unsubscribed'/>

   3.  Upon receiving the presence stanza of type "unsubscribed"
       addressed to the user, the user's server (1) MUST deliver that
       presence stanza to the user and (2) MUST initiate a "roster push"
       to all of the user's available resources that have requested the
       roster, containing an updated roster item for the contact with
       the 'subscription' attribute set to a value of "none" and with no
       'ask' attribute:

   <presence
       from='contact@domain'
       to='user@domain'
       type='unsubscribed'/>

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='none'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   As a result of this activity, the contact is now in the user's roster
   with a subscription state of "none", whereas the user is not in the
   contact's roster at all.

7.3 Creating a Mutual Subscription

   The user and contact can build on the foregoing to create a mutual
   subscription (i.e., a subscription of type "both"). The process is



Saint-Andre & Miller    Expires December 3, 2003               [Page 33]


Internet-Draft           XMPP Instant Messaging                June 2003


   defined below.

   1.  If the contact wants to create a mutual subscription, the contact
       MUST send a subscription request to the user (subject to
       configured preferences, the contact's client MAY send this
       automatically):

   <presence to='user@domain' type='subscribe'/>

   2.  As a result, the contact's server (1) MUST initiate a "roster
       push" to all available resources associated with the contact that
       have requested the roster, with the user still in the 'from'
       subscription state but with a pending 'to' subscription denoted
       by the inclusion of the ask='subscribe' attribute in the roster
       item; and (2) MUST route the presence stanza of type "subscribe"
       to the user, first stamping the 'from' address as the bare JID
       (<contact@domain>) of the contact:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='from'
           ask='subscribe'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       from='contact@domain'
       to='user@domain'
       type='subscribe'/>

   3.  Upon receiving the presence stanza of type "subscribe" addressed
       to the user, the user's server must determine if there is at
       least one active session in which the user has sent available
       presence and has requested the roster. If so, the user's server
       MUST deliver the subscription request to the user (if not, it
       MUST store the subscription request offline for delivery when
       this condition is next met). No matter when the subscription
       request is delivered, the user must then decide whether or not to
       accept it (subject to configured preferences, the user's client
       MAY accept or deny the subscription request without presenting it
       to the user). Here we assume the "happy path" that the user
       accepts the subscription request (the alternate flow of declining
       the subscription request is defined in Section 7.3.1). In this



Saint-Andre & Miller    Expires December 3, 2003               [Page 34]


Internet-Draft           XMPP Instant Messaging                June 2003


       case, the user's client MUST send a presence stanza of type
       "subscribed" to the contact in order to accept the subscription
       request.

   <presence to='contact@domain' type='subscribed'/>

   4.  As a result, the user's server (1) MUST initiate a "roster push"
       to all of the user's available resources that have requested the
       roster, containing a roster item for the contact with the
       'subscription' attribute set to a value of "both"; (2) route the
       presence stanza of type "subscribed" to the contact, first
       stamping the 'from' address as the bare JID (<user@domain>) of
       the user; and (3) send available presence from each of the user's
       available resources to the contact:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='both'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <presence
       from='user@domain'
       to='contact@domain'
       type='subscribed'/>

   <presence
       from='user@domain/resource'
       to='contact@domain'/>

   5.  Upon receiving the presence stanza of type "subscribed" addressed
       to the contact, the contact's server MUST first verify that the
       user is in the contact's roster with either of the following
       states: (a) subscription='none', ask='subscribe' or (b)
       subscription='from', ask='subscribe'. If the user is not in the
       contact's roster with either of those states, the contact's
       server MUST silently ignore the presence stanza of type
       "subscribed" (i.e., it MUST NOT route it to the contact, modify
       the contact's roster, or generate a roster push to the contact's
       available resources). If the user is in the contact's roster with
       either of those states, the contact's server (1) MUST deliver the
       presence stanza of type "subscribed" from the user to the
       contact; (2) MUST initiate a "roster push" to all available



Saint-Andre & Miller    Expires December 3, 2003               [Page 35]


Internet-Draft           XMPP Instant Messaging                June 2003


       resources associated with the contact that have requested the
       roster, containing an updated roster item for the user with the
       'subscription' attribute set to a value of "both"; and (3) MUST
       deliver the available presence stanza received from each of the
       user's available resources to each of the contact's available
       resources:

   <presence
       from='user@domain'
       to='contact@domain'
       type='subscribed'/>

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='both'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       from='user@domain/resource'
       to='contact@domain/resource'/>

   The user and the contact now have a mutual subscription to each
   other's presence -- i.e., the subscription is of type "both". The
   user's server MUST now send the user's current presence information
   to the contact. (Note: If at this point the user sends a subscription
   request to the contact or the contact sends a subscription request to
   the user, the sending user's server MUST silently ignore that request
   and not route it to the intended recipient.)

7.3.1 Alternate Flow: User Declines Subscription Request

   The above activity flow represents the "happy path" related to the
   contact's subscription request to the user. The main alternate flow
   occurs if the user denies the contact's subscription request.

   1.  If the user wants to deny the request, the user's client MUST
       send a presence stanza of type "unsubscribed" to the contact
       (instead of the presence stanza of type "subscribed" sent in Step
       3 of Section 7.3):

   <presence to='contact@domain' type='unsubscribed'/>




Saint-Andre & Miller    Expires December 3, 2003               [Page 36]


Internet-Draft           XMPP Instant Messaging                June 2003


   2.  As a result, the user's server MUST route the presence stanza of
       type "unsubscribed" to the contact, first stamping the 'from'
       address as the bare JID (<user@domain>) of the user:

   <presence
       from='user@domain'
       to='contact@domain'
       type='unsubscribed'/>

   3.  Upon receiving the presence stanza of type "unsubscribed"
       addressed to the contact, the contact's server (1) MUST deliver
       that presence stanza to the contact; and (2) MUST initiate a
       "roster push" to all available resources associated with the
       contact that have requested the roster, containing an updated
       roster item for the user with the 'subscription' attribute set to
       a value of "from" and with no 'ask' attribute:

   <presence
       to='contact@domain'
       from='user@domain'
       type='unsubscribed'/>

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='from'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   As a result of this activity, there has been no change in the
   subscription state; i.e., the contact is in the user's roster with a
   subscription state of "to" and the user is in the contact's roster
   with a subscription state of "from".

7.4 Unsubscribing

   At any time after subscribing to a contact's presence, a user MAY
   unsubscribe. While the XML that the user sends to make this happen is
   the same in all instances, the subsequent subscription state is
   different depending on the subscription state obtaining when the
   unsubscribe "command" was sent. Both possible scenarios are defined
   below.





Saint-Andre & Miller    Expires December 3, 2003               [Page 37]


Internet-Draft           XMPP Instant Messaging                June 2003


7.4.1 Case #1: Unsubscribing When Subscription is Not Mutual

   In the first case, the user has a subscription to the contact but the
   contact does not have a subscription to the user (i.e., the
   subscription is not yet mutual).

   1.  If the user wants to unsubscribe from the contact's presence, the
       user MUST send a presence stanza of type "unsubscribe" to the
       contact:

   <presence to='contact@domain' type='unsubscribe'/>

   2.  As a result, the user's server (1) MUST send a "roster push" to
       all of the user's available resources that have requested the
       roster, containing an updated roster item for the contact with
       the 'subscription' attribute set to a value of "none"; and (2)
       MUST route the presence stanza of type "unsubscribe" to the
       contact, first stamping the 'from' address as the bare JID
       (<user@domain>) of the user:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='none'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <presence
       from='user@domain'
       to='contact@domain'
       type='unsubscribe'/>

   3.  Upon receiving the presence stanza of type "unsubscribe"
       addressed to the contact, the contact's server (1) MUST initiate
       a "roster push" to all available resources associated with the
       contact that have requested the roster, containing an updated
       roster item for the user with the 'subscription' attribute set to
       a value of "none" (if the contact is offline, the contact's
       server MUST modify the roster item and send that modified item
       the next time the contact requests the roster); and (2) SHOULD
       deliver the unsubscribe command to the contact:






Saint-Andre & Miller    Expires December 3, 2003               [Page 38]


Internet-Draft           XMPP Instant Messaging                June 2003


   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='none'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       to='contact@domain'
       from='user@domain'
       type='unsubscribe'/>

   4.  The contact's server then (1) MAY send a presence stanza of type
       "unsubscribed" to the user; and (2) SHOULD send unavailable
       presence from the contact to the user:

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>

   5.  If the user's server receives a presence stanza of type
       "unsubscribed" and/or unavailable presence, it MUST deliver them
       to the user:

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>


7.4.2 Case #2: Unsubscribing When Subscription is Mutual

   In the second case, the user has a subscription to the contact and



Saint-Andre & Miller    Expires December 3, 2003               [Page 39]


Internet-Draft           XMPP Instant Messaging                June 2003


   the contact also has a subscription to the user (i.e., the
   subscription is mutual).

   1.  If the user wants to unsubscribe from the contact's presence, the
       user MUST send a presence stanza of type "unsubscribe" to the
       contact:

   <presence to='contact@domain' type='unsubscribe'/>

   2.  As a result, the user's server (1) MUST send a "roster push" to
       all of the user's available resources that have requested the
       roster, containing an updated roster item for the contact with
       the 'subscription' attribute set to a value of "from"; and (2)
       route the presence stanza of type "unsubscribe" to the contact,
       first stamping the 'from' address as the bare JID (<user@domain>)
       of the user:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='from'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <presence
       from='user@domain'
       to='contact@domain'
       type='unsubscribe'/>

   3.  Upon receiving the presence stanza of type "unsubscribe"
       addressed to the contact, the contact's server (1) MUST initiate
       a "roster push" to all available resources associated with the
       contact that have requested the roster, containing an updated
       roster item for the user with the 'subscription' attribute set to
       a value of "to" (if the contact is offline, the contact's server
       MUST modify the roster item and send that modified item the next
       time the contact requests the roster); and (2) SHOULD deliver the
       unsubscribe command to the contact:









Saint-Andre & Miller    Expires December 3, 2003               [Page 40]


Internet-Draft           XMPP Instant Messaging                June 2003


   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='to'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       to='contact@domain'
       from='user@domain'
       type='unsubscribe'/>

   4.  The contact's server then (1) MAY send a presence stanza of type
       "unsubscribed" to the user; and (2) SHOULD send unavailable
       presence from the contact to the user:

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>

   5.  If the user's server receives a presence stanza of type
       "unsubscribed" and/or unavailable presence, it MUST deliver them
       to the user:

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>

   Note: Obviously this does not result in removal of the roster item
   from the user's roster, and the contact still has a subscription to
   the user's presence. In order to both completely cancel a mutual
   subscription and fully remove the roster item from the user's roster,



Saint-Andre & Miller    Expires December 3, 2003               [Page 41]


Internet-Draft           XMPP Instant Messaging                June 2003


   the user should update the roster item with subscription='remove' as
   defined in Section 7.6.

7.5 Cancelling a Subscription

   At any time after approving a subscription request from a user, a
   contact MAY cancel that subscription. While the XML that the contact
   sends to make this happen is the same in all instances, the
   subsequent subscription state is different depending on the
   subscription state obtaining when the cancellation was sent. Both
   possible scenarios are defined below.

7.5.1 Case #1: Cancelling When Subscription is Not Mutual

   In the first case, the user has a subscription to the contact but the
   contact does not have a subscription to the user (i.e., the
   subscription is not yet mutual).

   1.  If the contact wants to cancel the user's subscription, the
       contact MUST send a presence stanza of type "unsubscribed" to the
       user:

   <presence to='user@domain' type='unsubscribed'/>

   2.  As a result, the contact's server (1) MUST send a "roster push"
       to all of the contact's available resources that have requested
       the roster, containing an updated roster item for the user with
       the 'subscription' attribute set to a value of "none"; (2) MUST
       route the presence stanza of type "unsubscribed" to the user,
       first stamping the 'from' address as the bare JID
       (<contact@domain>) of the contact; and (3) SHOULD send
       unavailable presence from the contact to the user:



















Saint-Andre & Miller    Expires December 3, 2003               [Page 42]


Internet-Draft           XMPP Instant Messaging                June 2003


   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='none'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>

   3.  Upon receiving the presence stanza of type "unsubscribed"
       addressed to the user, the user's server (1) MUST initiate a
       "roster push" to all of the user's available resources that have
       requested the roster, containing an updated roster item for the
       contact with the 'subscription' attribute set to a value of
       "none" (if the user is offline, the user's server MUST modify the
       roster item and send that modified item the next time the user
       requests the roster); and (2) SHOULD deliver the presence stanza
       of type "unsubscribed" to the user:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='none'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>





Saint-Andre & Miller    Expires December 3, 2003               [Page 43]


Internet-Draft           XMPP Instant Messaging                June 2003


   4.  Upon receiving the presence stanza of type "unavailable"
       addressed to the user, the user's server MUST deliver the
       unavailable presence to the user:

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>


7.5.2 Case #2: Cancelling When Subscription is Mutual

   In the second case, the user has a subscription to the contact and
   the contact also has a subscription to the user (i.e., the
   subscription is mutual).

   1.  If the contact wants to cancel the user's subscription, the
       contact MUST send a presence stanza of type "unsubscribed" to the
       user:

   <presence to='user@domain' type='unsubscribed'/>

   2.  As a result, the contact's server (1) MUST send a "roster push"
       to all of the contact's available resources that have requested
       the roster, containing an updated roster item for the user with
       the 'subscription' attribute set to a value of "to"; (2) MUST
       route the presence stanza of type "unsubscribed" to the user,
       first stamping the 'from' address as the bare JID
       (<contact@domain>) of the contact; and (3) SHOULD send
       unavailable presence from the contact to the user:





















Saint-Andre & Miller    Expires December 3, 2003               [Page 44]


Internet-Draft           XMPP Instant Messaging                June 2003


   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='to'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       from='contact@domain'
       to='user@domain'
       type='unsubscribed'/>

   <presence
       from='contact@domain'
       to='user@domain'
       type='unavailable'/>

   3.  Upon receiving the presence stanza of type "unsubscribed"
       addressed to the user, the user's server (1) MUST initiate a
       "roster push" to all of the user's available resources that have
       requested the roster, containing an updated roster item for the
       contact with the 'subscription' attribute set to a value of
       "from" (if the user is offline, the user's server MUST modify the
       roster item and send that modified item the next time the user
       requests the roster); and (2) SHOULD deliver the presence stanza
       of type "unsubscribed" to the user:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='from'
           name='MyContact'>
         <group>MyBuddies</group>
       </item>
     </query>
   </iq>

   <presence
       to='user@domain'
       from='contact@domain'
       type='unsubscribed'/>





Saint-Andre & Miller    Expires December 3, 2003               [Page 45]


Internet-Draft           XMPP Instant Messaging                June 2003


   4.  Upon receiving the presence stanza of type "unavailable"
       addressed to the user, the user's server MUST deliver the
       unavailable presence to the user:

   <presence
       to='user@domain'
       from='contact@domain'
       type='unavailable'/>

   Note: Obviously this does not result in removal of the roster item
   from the contact's roster, and the contact still has a subscription
   to the user's presence. In order to both completely cancel a mutual
   subscription and fully remove the roster item from the contact's
   roster, the contact should update the roster item with
   subscription='remove' as defined in Section 7.6.

7.6 Removing a Roster Item and Cancelling All Subscriptions

   Because there may be many steps involved in completely removing a
   roster item and cancelling subscriptions in both directions, XMPP IM
   includes a "shortcut" method for doing so. The process may be
   initiated no matter what the current subscription state is by sending
   a roster set containing an item for the contact with the
   'subscription' attribute set to a value of "remove":

   <iq type='set' id='remove1'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='remove'/>
     </query>
   </iq>

   When the user removes a contact from his or her roster by setting the
   'subscription' attribute to a value of "remove", the user's server
   (1) MUST automatically cancel any existing presence subscription
   between the user and the contact (both 'to' and 'from' as
   appropriate); (2) MUST remove the roster item from the user's roster
   and inform all of the user's available resources of the roster item
   removal; (3) MUST inform the resource that initiated the removal of
   success; and (4) SHOULD send unavailable presence to the contact:










Saint-Andre & Miller    Expires December 3, 2003               [Page 46]


Internet-Draft           XMPP Instant Messaging                June 2003


   <presence
       from='user@domain'
       to='contact@domain'
       type='unsubscribe'/>

   <presence
       from='user@domain'
       to='contact@domain'
       type='unsubscribed'/>

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='contact@domain'
           subscription='remove'/>
     </query>
   </iq>

   <iq type='result' id='remove1'/>

   <presence
       from='user@domain'
       to='contact@domain'
       type='unavailable'/>

   Upon receiving the presence stanza of type "unsubscribe", the
   contact's server (1) MUST initiate a "roster push" to all available
   resources associated with the contact that have requested the roster,
   containing an updated roster item for the user with the
   'subscription' attribute set to a value of "to" (if the contact is
   offline, the contact's server MUST modify the roster item and send
   that modified item the next time the contact requests the roster);
   and (2) SHOULD also deliver the unsubscribe command to the contact:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='to'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       to='contact@domain'
       from='user@domain'



Saint-Andre & Miller    Expires December 3, 2003               [Page 47]


Internet-Draft           XMPP Instant Messaging                June 2003


       type='unsubscribe'/>

   Upon receiving the presence stanza of type "unsubscribed", the
   contact's server (1) MUST initiate a "roster push" to all available
   resources associated with the contact that have requested the roster,
   containing an updated roster item for the user with the
   'subscription' attribute set to a value of "none" (if the contact is
   offline, the contact's server MUST modify the roster item and send
   that modified item the next time the contact requests the roster);
   and (2) SHOULD also deliver the unsubscribe command to the contact:

   <iq type='set'>
     <query xmlns='jabber:iq:roster'>
       <item
           jid='user@domain'
           subscription='none'
           name='SomeUser'>
         <group>SomeGroup</group>
       </item>
     </query>
   </iq>

   <presence
       to='contact@domain'
       from='user@domain'
       type='unsubscribed'/>

   Upon receiving the presence stanza of type "unavailable" addressed to
   the contact, the contact's server MUST deliver the unavailable
   presence to the user:

   <presence
       from='user@domain'
       to='contact@domain'
       type='unavailable'/>

   Note that when the user removes the contact from the user's roster,
   the end state of the contact's roster is that the user is still in
   the contact's roster with a subscription state of "none"; in order to
   completely remove the roster item for the user, the contact needs to
   also send a roster removal request.










Saint-Andre & Miller    Expires December 3, 2003               [Page 48]


Internet-Draft           XMPP Instant Messaging                June 2003


8. Blocking Communication

   Most instant messaging systems have found it necessary to implement
   some method for users to block communications from particular other
   users (this is also required by sections 5.1.5, 5.1.15, 5.3.2, and
   5.4.10 of RFC 2779 [2]). In XMPP this is done using the
   'jabber:iq:privacy' namespace by managing one's privacy lists.

   Server-side privacy lists enable successful completion of the
   following use cases:

   o  Retrieving one's privacy lists.

   o  Adding, removing, and editing one's privacy lists.

   o  Setting, changing, or declining active lists.

   o  Setting, changing, or declining the default list (i.e., the list
      that is active by default).

   o  Allowing or denying messages based on JID, group, or subscription
      type (or globally).

   o  Allowing or denying inbound presence notifications based on JID,
      group, or subscription type (or globally).

   o  Allowing or denying outbound presence notifications based on JID,
      group, or subscription type (or globally).

   o  Allowing or denying IQs based on JID, group, or subscription type
      (or globally).

   o  Allowing or denying all communications based on JID, group, or
      subscription type (or globally).

   Note: presence notifications do not include presence subscriptions,
   only presence information that is broadcasted to entities that are
   subscribed to a user's presence information. Thus this includes
   presence stanzas with no 'type' attribute or of type='unavailable'
   only.

8.1 Syntax

   A user MAY define one or more privacy lists, which are stored by the
   user's server. Each <list/> element contains one or more rules in the
   form of <item/> elements, and each <item/> element uses attributes to
   define a privacy rule type, a specific value to which the rules
   applies, the relevant action, and the place of the item in the



Saint-Andre & Miller    Expires December 3, 2003               [Page 49]


Internet-Draft           XMPP Instant Messaging                June 2003


   processing order.

   The syntax is as follows:

   <iq>
     <query xmlns='jabber:iq:privacy'>
       <list name='foo'>
         <item
             type='[jid|group|subscription]'
             value='bar'
             action='[accept|deny]'
             order='nonNegativeInteger'/>
       </list>
     </query>
   </iq>

   If the type is "jid", then the 'value' attribute MUST contain a valid
   Jabber ID. JIDs are matched in the following order: <user@domain/
   resource>, then <user@domain>, then <domain/resource>, then <domain>.
   If the value is <user@domain>, then any connected resource for that
   user@domain matches. If the value is <domain/resource>, then only
   that resource matches. If the value is <domain>, then any user@domain
   (or subdomain) matches.

   If the type is "group", then the 'value' attribute MUST contain the
   name of a group in the user's roster. (If a client attempts to
   update, create, or delete a list item with a group that is not in the
   user's roster, the server MUST return to the client an
   <item-not-found/> stanza error.)

   If the type is "subscription", then the 'value' attribute MUST be one
   of "both", "to", "from", or "none" as defined in XMPP Core [1].

   If no 'type' attribute is included, the rule provides the
   "fall-through" case.

   The 'action' attribute MUST be included and its value MUST be either
   "accept" or "deny".

   The 'order' attribute MUST be included and its value MUST be a
   non-negative integer that is unique among all items in the list. (If
   a client attempts to create or update a list with non-unique order
   values, the server MUST return to the client a <bad-request/> stanza
   error.

   Within the 'jabber:iq:privacy' namespace, the <query/> child of a
   client-generated IQ stanza of type "set" MUST NOT include more than
   one child element (i.e., the stanza must contain only one <active/>



Saint-Andre & Miller    Expires December 3, 2003               [Page 50]


Internet-Draft           XMPP Instant Messaging                June 2003


   element, one <default/> element, or one <list/> element); if a client
   violates this rule, the server MUST return to the client a
   <bad-request/> stanza error.)

   When a client adds or updates a privacy list, the <list/> element
   MUST contain at least one <item/> child element; if a client violates
   this rule, the server MUST return to the client a <bad-request/>
   stanza error.

   When a client updates a privacy list, it must include all of the
   desired items (i.e., not a "delta").

8.2 Business Rules

   1.  If there is an active list set for a session, it affects only the
       session for which it is activated, and only for the duration of
       the session. Only the active list for that session is processed
       (i.e., the default list is ignored).

   2.  The default list applies to the user as a whole, and is processed
       if there is no active list set for the target session/resource to
       which a stanza is addressed, or if there are no current sessions
       for the user.

   3.  If there is no active list set for a session (or there are no
       current sessions for the user), and there is no default list,
       then all stanzas SHOULD BE accepted or appropriately processed by
       the server on behalf of the user.

   4.  Privacy lists SHOULD be the first routing and delivery rule
       applied by a server, trumping the other rules specified in
       Section 9.

   5.  The order in which privacy list items are processed by the server
       is important. List items MUST be processed in ascending order
       determined by the values of the 'order' attribute for each <item/
       >.

   6.  As soon as a stanza is matched against a privacy list, the server
       SHOULD appropriately handle the stanza and cease processing.

   7.  If no fall-through item is provided in a list, the fall-through
       action is assumed to be "accept".

   8.  When a user updates the definition for a list or adds a new list
       (whether or not it is active), the server SHOULD NOT "push" that
       information out to all of the user's available resources that
       have requested the roster's account, as is done for rosters. If a



Saint-Andre & Miller    Expires December 3, 2003               [Page 51]


Internet-Draft           XMPP Instant Messaging                June 2003


       client or user wants to retrieve the current privacy list
       information, it SHOULD request the relevant list.

   9.  If a change to the subscription state or roster group of a roster
       item occurs during a user's session and the active session,
       subsequent processing of the active list MUST be based on the
       changed state or group.


8.3 Retrieving One's Privacy Lists

   Example: Client requests names of privacy lists from server:

   <iq type='get' id='getlist1'>
     <query xmlns='jabber:iq:privacy'/>
   </iq>

   Example: Server sends names of privacy lists to client, preceded by
   active list and default list:

   <iq type='result' id='getlist1' to='romeo@montague.net/orchard'>
     <query xmlns='jabber:iq:privacy'>
       <active name='private'/>
       <default name='public'/>
       <list name='public'/>
       <list name='private'/>
       <list name='special'/>
     </query>
   </iq>

   Example: Client requests a privacy list from server:

   <iq type='get' id='getlist2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='public'/>
     </query>
   </iq>














Saint-Andre & Miller    Expires December 3, 2003               [Page 52]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Server sends a privacy list to client:

   <iq type='result' id='getlist2' to='romeo@montague.net/orchard'>
     <query xmlns='jabber:iq:privacy'>
       <list name='public'>
         <item jid='tybalt@capulet.com' action='deny' order='1'/>
         <item action='allow' order='2'/>
       </list>
     </query>
   </iq>

   Example: Client requests another privacy list from server:

   <iq type='get' id='getlist3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='private'/>
     </query>
   </iq>

   Example: Server sends another privacy list to client:

   <iq type='result' id='getlist3' to='romeo@montague.net/orchard'>
     <query xmlns='jabber:iq:privacy'>
       <list name='private'>
         <item type='subscription' value='both'
               action='allow' order='10'/>
         <item action='deny' order='15'/>
       </list>
     </query>
   </iq>

   Example: Client requests yet another privacy list from server:

   <iq type='get' id='getlist4'>
     <query xmlns='jabber:iq:privacy'>
       <list name='special'/>
     </query>
   </iq>













Saint-Andre & Miller    Expires December 3, 2003               [Page 53]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Server sends yet another privacy list to client:

   <iq type='result' id='getlist4' to='romeo@montague.net/orchard'>
     <query xmlns='jabber:iq:privacy'>
       <list name='special'>
         <item
             type='jid'
             value='juliet@capulet.com'
             action='allow'
             order='6'/>
         <item
             type='jid'
             value='benvolio@shakespeare.lit'
             action='allow'
             order='7'/>
         <item
             type='jid'
             value='mercutio@verona.it'
             action='allow'
             order='42'/>
         <item action='deny'/>
       </list>
     </query>
   </iq>

   In this example, the user has three lists: (1) 'public', which allows
   communications from everyone except one specific entity (this is the
   default list); (2) 'private', which allows communications only with
   contacts who have a bidirectional subscription with the user (this is
   the active list); and (3) 'special', which allows communications only
   with three specific entities.

   If the user attempts to retrieve a list but a list by that name does
   not exist, the server MUST return an <item-not-found> stanza error to
   the user:

   Example: Client attempts to retrieve non-existent list:

   <iq type='error' id='getlist5'>
     <query xmlns='jabber:iq:privacy'>
       <list name='The Empty Set'/>
     </query>
     <error type='cancel'>
       <item-not-found
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </iq>




Saint-Andre & Miller    Expires December 3, 2003               [Page 54]


Internet-Draft           XMPP Instant Messaging                June 2003


   The user is allowed to retrieve only one list at a time. If the user
   attempts to retrieve more than one list in the same request, the
   server MUST return a <bad request> stanza error to the user:

   Example: Client attempts to retrieve more than one list:

   <iq type='error' id='getlist6'>
     <query xmlns='jabber:iq:privacy'>
       <list name='public'/>
       <list name='private'/>
       <list name='special'/>
     </query>
     <error type='modify'>
       <bad-request
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
     </error>
   </iq>


8.4 Managing Active Lists

   In order to set or change the active list currently being applied by
   the server, the user MUST send an IQ stanza of type "set" with a
   <query/> element qualified by the 'jabber:iq:privacy' namespace that
   contains an empty <active/> child element possessing a 'name'
   attribute whose value is set to the desired list name.

   Example: Client requests change of active list:

   <iq type='set' id='active1'>
     <query xmlns='jabber:iq:privacy'>
       <active name='special'/>
     </query>
   </iq>

   The server MUST activate and apply the requested list before sending
   the result back to the client.

   Example: Server acknowledges success of active list change:

   <iq type='result' id='active1' to='juliet@capulet.com/balcony'/>

   If the user attempts to set an active list but a list by that name
   does not exist, the server MUST return an <item-not-found> stanza
   error to the user:






Saint-Andre & Miller    Expires December 3, 2003               [Page 55]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Client attempts to set a non-existent list as active:

   <iq type='error' id='active2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='The Empty Set'/>
     </query>
     <error type='cancel'>
       <item-not-found
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
     </error>
   </iq>

   In order to decline the use of any active list, a user MUST send an
   empty <active/> element with no name.

   Example: Client declines the use of active lists:

   <iq type='set' id='active2'>
     <query xmlns='jabber:iq:privacy'>
       <active/>
     </query>
   </iq>


8.5 Managing the Default List

   In order to change its default list, the user MUST send an IQ stanza
   of type "set" with a <query/> element qualified by the
   'jabber:iq:privacy' namespace that contains an empty <default/> child
   element possessing a 'name' attribute whose value is set to the
   desired list name.

   Example: Client requests change of default list:

   <iq type='set' id='default1'>
     <query xmlns='jabber:iq:privacy'>
       <default name='special'/>
     </query>
   </iq>

   Example: Server acknowledges success of default list change:

   <iq type='result' id='default1' to='juliet@capulet.com/balcony'/>

   If the user attempts to set a default list but a list by that name
   does not exist, the server MUST return an <item-not-found> stanza
   error to the user:




Saint-Andre & Miller    Expires December 3, 2003               [Page 56]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Client attempts to set a non-existent list as default:

   <iq type='error' id='default2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='The Empty Set'/>
     </query>
     <error type='cancel'>
       <item-not-found
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
     </error>
   </iq>

   In order to decline the use of a default list (i.e., to use the
   domain's stanza routing rules at all times), a user MUST send an
   empty <default/> element with no name.

   Example: Client declines the use of the default list:

   <iq type='set' id='default2'>
     <query xmlns='jabber:iq:privacy'>
       <default/>
     </query>
   </iq>


8.6 Editing a Privacy List

   In order to edit a privacy list, the user MUST send an IQ stanza of
   type "set" with a <query/> element qualified by the
   'jabber:iq:privacy' namespace that contains one <list/> child element
   possessing a 'name' attribute whose value is set to the list name the
   user would like to edit. The <list/> element MUST contain one or more
   <item/> elements, which specify the user's desired changes to the
   list by including all elements in the list (not the "delta").

   Example: Client edits a privacy list:

   <iq type='set' id='edit1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='public'>
         <item type='jid' value='tybalt@capulet.com'
               action='deny' order='3'/>
         <item type='jid' value='paris@shakespeare.lit'
               action='deny' order='5'/>
         <item action='allow' order='68'/>
       </list>
     </query>
   </iq>



Saint-Andre & Miller    Expires December 3, 2003               [Page 57]


Internet-Draft           XMPP Instant Messaging                June 2003


   Note: The value of the 'order' attribute for any given item is not
   fixed. Thus in the foregoing example if the user would like to add 4
   items between the "tybalt@capulet.com" item and the
   "paris@shakespeare.lit" item, the user's client MUST renumber the
   relevant items before submitting the list to the server.

   Example: Server acknowledges success of list edit:

   <iq type='result' id='edit1' to='juliet@capulet.com/balcony'/>


8.7 Adding a New Privacy List

   The same protocol used to edit an existing list is used to create a
   new list. If the list name matches that of an existing list, the
   request to add a new list will overwrite the old one.

8.8 Removing a Privacy List

   In order to remove a privacy list, the user MUST send an IQ stanza of
   type "set" with a <query/> element qualified by the
   'jabber:iq:privacy' namespace that contains one empty <list/> child
   element possessing a 'name' attribute whose value is set to the list
   name the user would like to remove.

   Example: Client removes a privacy list:

   <iq type='set' id='remove1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='private'/>
     </query>
   </iq>

   Example: Server acknowledges success of list removal:

   <iq type='result' id='remove1' to='juliet@capulet.com/balcony'/>

   If a user attempts to remove an active list or the default list, the
   server MUST return a <conflict/> stanza error to the user. The user
   MUST first set another list to active or default before removing it.

   If the user attempts to remove a list but a list by that name does
   not exist, the server MUST return an <item-not-found> stanza error to
   the user:

   If the user attempts to remove more than one list in the same
   request, the server MUST return a <bad request> stanza error to the
   user.



Saint-Andre & Miller    Expires December 3, 2003               [Page 58]


Internet-Draft           XMPP Instant Messaging                June 2003


8.9 Blocking Messages

   Server-side privacy lists enable a user to block incoming messages
   from other users based on the other user's JID, roster group, or
   subscription status (or globally). The following examples illustrate
   the protocol.

   Example: User blocks based on JID:

   <iq type='set' id='msg1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='message-jid-example'>
         <item type='jid' value='tybalt@capulet.com'
               action='deny' order='3'>
           <message/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive messages from the user with the specified JID.

   Example: User blocks based on roster group:

   <iq type='set' id='msg2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='message-group-example'>
         <item type='group' value='Enemies' action='deny' order='4'>
           <message/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive messages from any users in the specified roster
   group.













Saint-Andre & Miller    Expires December 3, 2003               [Page 59]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks based on subscription type:

   <iq type='set' id='msg3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='message-sub-example'>
         <item type='subscription' value='none' action='deny' order='5'>
           <message/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive messages from any users with the specified
   subscription type.

   Example: User blocks globally:

   <iq type='set' id='msg4'>
     <query xmlns='jabber:iq:privacy'>
       <list name='message-global-example'>
         <item action='deny' order='6'>
           <message/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive messages from any other users.

8.10 Blocking Inbound Presence Notifications

   Server-side privacy lists enable a user to block incoming presence
   notifications from other users based on the other user's JID, roster
   group, or subscription status (or globally). The following examples
   illustrate the protocol.

   Note: presence notifications do not include presence subscriptions,
   only presence information that is broadcasted to the user because the
   user previously subscribed to a contact's presence information. Thus
   this includes presence stanzas with no 'type' attribute or of
   type='unavailable' only.








Saint-Andre & Miller    Expires December 3, 2003               [Page 60]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks based on JID:

   <iq type='set' id='presin1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presin-jid-example'>
         <item type='jid' value='tybalt@capulet.com'
               action='deny' order='7'>
           <presence-in/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive presence notifications from the user with the
   specified JID.

   Example: User blocks based on roster group:

   <iq type='set' id='presin2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presin-group-example'>
         <item type='group' value='Enemies' action='deny' order='8'>
           <presence-in/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive presence notifications from any users in the
   specified roster group.

   Example: User blocks based on subscription type:

   <iq type='set' id='presin3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presin-sub-example'>
         <item type='subscription' value='to' action='deny' order='9'>
           <presence-in/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive presence notifications from any users with the
   specified subscription type.



Saint-Andre & Miller    Expires December 3, 2003               [Page 61]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks globally:

   <iq type='set' id='presin4'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presin-global-example'>
         <item action='deny' order='11'>
           <presence-in/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive presence notifications from any other users.

8.11 Blocking Outbound Presence Notifications

   Server-side privacy lists enable a user to block outgoing presence
   notifications to other users based on the other user's JID, roster
   group, or subscription status (or globally). The following examples
   illustrate the protocol.

   Note: presence notifications do not include presence subscriptions,
   only presence information that is broadcasted to contacts because
   those contacts previously subscribed to the user's presence
   information. Thus this includes presence stanzas with no 'type'
   attribute or of type='unavailable' only. Note also that because
   information about last activity MAY be requested by a contact (as
   defined in Section 4.5), a user SHOULD block both outbound presence
   and IQs in relation to any given entity.

   Example: User blocks based on JID:

   <iq type='set' id='presout1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presout-jid-example'>
         <item type='jid' value='tybalt@capulet.com'
               action='deny' order='13'>
           <presence-out/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not send presence notifications to the user with the specified
   JID.




Saint-Andre & Miller    Expires December 3, 2003               [Page 62]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks based on roster group:

   <iq type='set' id='presout2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presout-group-example'>
         <item type='group' value='Enemies' action='deny' order='15'>
           <presence-out/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not send presence notifications to any users in the specified
   roster group.

   Example: User blocks based on subscription type:

   <iq type='set' id='presout3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presout-sub-example'>
         <item type='subscription' value='from'
               action='deny' order='17'>
           <presence-out/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not send presence notifications to any users with the specified
   subscription type.

   Example: User blocks globally:

   <iq type='set' id='presout4'>
     <query xmlns='jabber:iq:privacy'>
       <list name='presout-global-example'>
         <item action='deny' order='23'>
           <presence-out/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not send presence notifications to any other users.




Saint-Andre & Miller    Expires December 3, 2003               [Page 63]


Internet-Draft           XMPP Instant Messaging                June 2003


8.12 Blocking IQs

   Server-side privacy lists enable a user to block incoming IQ requests
   of type "get" or "set" from other users based on the other user's
   JID, roster group, or subscription status (or globally). The
   following examples illustrate the protocol.

   Example: User blocks based on JID:

   <iq type='set' id='iq1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='iq-jid-example'>
         <item type='jid' value='tybalt@capulet.com'
               action='deny' order='29'>
           <iq/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive IQ requests of type "get" or "set" from the user
   with the specified JID.

   Example: User blocks based on roster group:

   <iq type='set' id='iq2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='iq-group-example'>
         <item type='group' value='Enemies' action='deny' order='31'>
           <iq/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive IQ requests of type "get" or "set" from any users in
   the specified roster group.












Saint-Andre & Miller    Expires December 3, 2003               [Page 64]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks based on subscription type:

   <iq type='set' id='iq3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='iq-sub-example'>
         <item type='subscription' value='none'
               action='deny' order='17'>
           <iq/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive IQ requests of type "get" or "set" from any users
   with the specified subscription type.

   Example: User blocks globally:

   <iq type='set' id='iq4'>
     <query xmlns='jabber:iq:privacy'>
       <list name='iq-global-example'>
         <item action='deny' order='1'>
           <iq/>
         </item>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive IQ requests of type "get" or "set" from any other
   users.

8.13 Blocking All Communication

   Server-side privacy lists enable a user to block all communications
   from and presence to other users based on the other user's JID,
   roster group, or subscription status (or globally). The following
   examples illustrate the protocol.












Saint-Andre & Miller    Expires December 3, 2003               [Page 65]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks based on JID:

   <iq type='set' id='all1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='all-jid-example'>
         <item type='jid' value='tybalt@capulet.com'
               action='deny' order='23'/>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive any communications from, nor send any stanzas to,
   the user with the specified JID.

   Example: User blocks based on roster group:

   <iq type='set' id='all2'>
     <query xmlns='jabber:iq:privacy'>
       <list name='all-group-example'>
         <item type='group' value='Enemies' action='deny' order='13'/>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive any communications from, nor send any stanzas to,
   any users in the specified roster group.

   Example: User blocks based on subscription type:

   <iq type='set' id='all3'>
     <query xmlns='jabber:iq:privacy'>
       <list name='all-sub-example'>
         <item type='subscription' value='none'
               action='deny' order='11'/>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive any communications from, nor send any stanzas to,
   any users with the specified subscription type.








Saint-Andre & Miller    Expires December 3, 2003               [Page 66]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: User blocks globally:

   <iq type='set' id='all4'>
     <query xmlns='jabber:iq:privacy'>
       <list name='all-global-example'>
         <item action='deny' order='7'/>
       </list>
     </query>
   </iq>

   As a result of creating and applying the foregoing list, the user
   will not receive any communications from, nor send any stanzas to,
   any other users.

8.14 Blocked Entity Attempts to Communicate with User

   If a blocked entity attempts to send messages or presence
   notifications to the user, the user's server SHOULD silently drop the
   stanza and MUST NOT return an error to the sending entity.

   If a blocked entity attempts to send an IQ stanza of type "get" or
   "set" to the user, the user's server MUST return to the sending
   entity a <feature-not-implemented/> stanza error, since this is the
   standard error code sent from a client that does not understand the
   namespace of an IQ get or set. IQ stanzas of other types SHOULD be
   silently dropped by the server.

   Example: Blocked entity attempts to send IQ get:

   <iq
       type='get'
       to='romeo@montague.net'
       from='tybalt@capulet.com/pda'
       id='probing1'>
     <query xmlns='jabber:iq:last'/>
   </iq>















Saint-Andre & Miller    Expires December 3, 2003               [Page 67]


Internet-Draft           XMPP Instant Messaging                June 2003


   Example: Server returns error to blocked entity:

   <iq
       type='error'
       from='romeo@montague.net'
       to='tybalt@capulet.com/pda'
       id='probing1'>
     <query xmlns='jabber:iq:last'/>
     <error type='cancel'>
       <feature-not-implemented
           xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'>
     </error>
   </iq>


8.15 Higher-Level Heuristics

   When building a representation of a higher-level privacy heuristic, a
   client SHOULD use the simplest possible representation.

   For example, the heuristic "block all communications with any user
   not in my roster" could be constructed in any of the following ways:

   o  accept communications from all JIDs in my roster (i.e., listing
      each JID as a separate list item), but deny communications with
      everyone else

   o  accept communications from any user who is in one of the groups
      that make up my roster (i.e., listing each group as a separate
      list item), but deny communications from everyone else

   o  accept communications from any user with whom I have a
      subscription of 'both' or 'to' or 'from' (i.e., listing each
      subscription value separately), but deny communications from
      everyone else

   o  deny communications from anyone whose subscription state is 'none'

   The final representation is the simplest and SHOULD be used; here is
   the XML that would be sent in this case:

   <iq type='set' id='heuristic1'>
     <query xmlns='jabber:iq:privacy'>
       <list name='heuristic-example'>
         <item type='subscription' value='none'
               action='deny' order='437'/>
       </list>
     </query>



Saint-Andre & Miller    Expires December 3, 2003               [Page 68]


Internet-Draft           XMPP Instant Messaging                June 2003


   </iq>


















































Saint-Andre & Miller    Expires December 3, 2003               [Page 69]


Internet-Draft           XMPP Instant Messaging                June 2003


9. Server Rules for Handling XML Stanzas

   Each server implementation will contain its own "delivery tree" for
   handling stanzas it receives. Such a tree determines whether a stanza
   needs to be routed to another domain, processed internally, or
   delivered to a connected resource associated with a registered user.
   The following rules apply:

9.1 No 'to' Address

   If the stanza possesses no 'to' attribute, the server SHOULD process
   it on behalf of the entity that sent it. Because all stanzas received
   from other servers MUST possess a 'to' attribute, this rule applies
   only to stanzas received from an entity that is connected to the
   server (usually an active client session). If the server receives a
   presence stanza with no 'to' attribute, the server SHOULD broadcast
   it to the entities that are subscribed to the sending entity's
   presence as defined under Section 4.1. If the server receives an IQ
   stanza of type "get" or "set" with no 'to' attribute and it
   understands the namespace that qualifies the content of the stanza,
   it MUST process the stanza on behalf of sending entity (where the
   meaning of "process" is determined by the semantics of the qualifying
   namespace).

9.2 Foreign Domain

   If the hostname of the domain identifier portion of the JID contained
   in the 'to' attribute does not match one of the configured hostnames
   of the server itself or a subdomain thereof, the server SHOULD route
   the stanza to the foreign domain (subject to local service
   provisioning and security policies regarding inter-domain
   communication). If routing to the recipient's server is unsuccessful,
   the sender's server MUST return an error to the sender; if the
   recipient's server can be contacted but delivery by the recipient's
   server to the recipient is unsuccessful, the recipient's server MUST
   return an error to the sender by way of the sender's server.

9.3 Subdomain

   If the hostname of the domain identifier portion of the JID contained
   in the 'to' attribute matches a subdomain of one of the configured
   hostnames of the server itself, the server MAY process the stanza
   itself or MAY route the stanza to a specialized service that is
   responsible for that subdomain (if any).

9.4 Bare Domain or Specific Resource

   If the hostname of the domain identifier portion of the JID contained



Saint-Andre & Miller    Expires December 3, 2003               [Page 70]


Internet-Draft           XMPP Instant Messaging                June 2003


   in the 'to' attribute matches the hostname of the server itself and
   the JID contained in the 'to' attribute is of the form <domain> or
   <domain/resource>, the server (or a defined resource thereof) SHOULD
   process the stanza as appropriate for the stanza type. If the stanza
   is an IQ stanza and the server understands the namespace that
   qualifies the content of the stanza, the server SHOULD process the
   request according to the semantics of the qualifying namespace, and
   MUST reply with an IQ of type "result" or "error".

9.5 User in Same Domain

   If the hostname of the domain identifier portion of the JID contained
   in the 'to' attribute matches the hostname of the server itself and
   the JID contained in the 'to' attribute is of the form <user@domain>
   or <user@domain/resource>, the server SHOULD first apply any privacy
   rules (Section 8) that are in force. If privacy rules allow the
   stanza, it SHOULD be routed or delivered to the intended recipient of
   the stanza as represented by the JID contained in the 'to' attribute.
   The following rules apply:

   1.  If the JID contains a resource identifier (i.e., is of the form
       <user@domain/resource>) and there is an available resource whose
       authzid matches the full JID, the recipient's server SHOULD
       deliver the stanza to the session that exactly matches the
       resource identifier.

   2.  If the JID contains a resource identifier and there is no
       available resource whose authzid matches the full JID, the
       recipient's server SHOULD return to the sender a
       <recipient-unavailable/> stanza error.

   3.  If the JID is of the form <user@domain> and there is at least one
       available resource available for the user, the recipient's server
       MUST follow these rules:

       1.  For message stanzas, the server SHOULD deliver the stanza to
           the available resource that provided the highest value for
           the <priority/> element (if the resource did not provide a
           priority, the server SHOULD consider it to have provided a
           value of zero). If two resources have the same priority, the
           server MAY use some other rule (e.g., most recent connect
           time or activity time) to choose between them. However, the
           server MUST NOT deliver the stanza to an available resource
           that provided a negative value for the <priority/> element.

       2.  For presence stanzas other than those of type "probe", the
           server MUST deliver the stanza to all available resources,
           except that the server MUST NOT deliver the stanza to an



Saint-Andre & Miller    Expires December 3, 2003               [Page 71]


Internet-Draft           XMPP Instant Messaging                June 2003


           available resource that provided a negative value for the
           <priority/> element; for presence probes, the server SHOULD
           reply based on the rules defined in Section 4.1.

       3.  For IQ stanzas, the server SHOULD deliver the stanza to all
           available resources, except that the server MUST NOT deliver
           the stanza to an available resource that provided a negative
           value for the <priority/> element.

   4.  If the JID is of the form <user@domain> and there are no
       available resources associated with the user (e.g., an instant
       messaging user is offline), how the stanza is handled depends on
       the stanza type:

       1.  For presence stanzas of type "subscribe", the server MUST
           maintain a record of the stanza, as specified under Section
           4.1.

       2.  For all other presence stanzas, the server SHOULD silently
           ignore the stanza by not storing it for later delivery or
           replying to it on behalf of the user.

       3.  For message stanzas, the server MAY choose to store the
           stanza on behalf of the user and deliver it when the user
           next becomes available. However, if offline message storage
           is not enabled, the server MUST return to the sender a
           <service-unavailable/> stanza error. (Note: offline message
           storage is not defined in XMPP since it strictly is a matter
           of implementation and service provisioning.)

       4.  For IQ stanzas, the server MUST reply with either an IQ
           result or an IQ error. Specifically, if the semantics of the
           qualifying namespace define a reply that the server can
           provide, the server MUST reply to the stanza on behalf of the
           user (e.g., this is the case with the 'jabber:iq:last'
           protocol defined above); if not, the server MUST reply with a
           <service-unavailable/> stanza error.














Saint-Andre & Miller    Expires December 3, 2003               [Page 72]


Internet-Draft           XMPP Instant Messaging                June 2003


10. IANA Considerations

   For several related IANA considerations, refer to XMPP Core [1].

10.1 XML Namespace Name for Session Data

   A URN sub-namespace for session-related data in the Extensible
   Messaging and Presence Protocol (XMPP) is defined as follows.

   URI: urn:ietf:params:xml:ns:xmpp-session

   Specification: [RFCXXXX]

   Description: This is the XML namespace name for session-related data
      in the Extensible Messaging and Presence Protocol (XMPP) as
      defined by [RFCXXXX].

   Registrant Contact: IETF, XMPP Working Group, <xmppwg@jabber.org>

































Saint-Andre & Miller    Expires December 3, 2003               [Page 73]


Internet-Draft           XMPP Instant Messaging                June 2003


11. Security Considerations

   For security considerations, refer to the relevant section of XMPP
   Core [1].















































Saint-Andre & Miller    Expires December 3, 2003               [Page 74]


Internet-Draft           XMPP Instant Messaging                June 2003


Normative References

   [1]  Saint-Andre, P. and J. Miller, "XMPP Core",
        draft-ietf-xmpp-core-13 (work in progress), June 2003.

   [2]  Day, M., Aggarwal, S. and J. Vincent, "Instant Messaging /
        Presence Protocol Requirements", RFC 2779, February 2000.

   [3]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", BCP 14, RFC 2119, March 1997.









































Saint-Andre & Miller    Expires December 3, 2003               [Page 75]


Internet-Draft           XMPP Instant Messaging                June 2003


Informative References

   [4]  Jabber Software Foundation, "Jabber Software Foundation", August
        2001, <http://www.jabber.org/>.

   [5]  Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
        Instant Messaging", RFC 2778, February 2000, <http://
        www.ietf.org/rfc/rfc2778.txt>.

   [6]  Dawson, F. and T. Howes, "vCard MIME Directory Profile", RFC
        2426, September 1998.


Authors' Addresses

   Peter Saint-Andre
   Jabber Software Foundation

   EMail: stpeter@jabber.org
   URI:   http://www.jabber.org/people/stpeter.php


   Jeremie Miller
   Jabber Software Foundation

   EMail: jeremie@jabber.org
   URI:   http://www.jabber.org/people/jer.php
























Saint-Andre & Miller    Expires December 3, 2003               [Page 76]


Internet-Draft           XMPP Instant Messaging                June 2003


Appendix A. vCards

   Sections 3.1.3 and 4.1.4 of RFC 2779 [2] require that it be possible
   to retrieve contact information for other users (e.g., telephone
   number or email address). An XML representation of the vCard
   specification defined in RFC 2426 [6] is in common use within the
   Jabber community to provide such information. Documentation of this
   protocol is maintained by the Jabber Software Foundation [4] at
   <http://www.jabber.org/protocol/> but is out of scope for this
   document.









































Saint-Andre & Miller    Expires December 3, 2003               [Page 77]


Internet-Draft           XMPP Instant Messaging                June 2003


Appendix B. XML Schemas

   The following XML schemas are descriptive, not normative.

B.1 session

   <?xml version='1.0' encoding='UTF-8'?>
   <xs:schema
       xmlns:xs='http://www.w3.org/2001/XMLSchema'
       targetNamespace='urn:ietf:params:xml:ns:xmpp-session'
       xmlns='urn:ietf:params:xml:ns:xmpp-session'
       elementFormDefault='qualified'>

     <xs:element name='session' type='empty'/>

     <xs:simpleType name='empty'>
       <xs:restriction base='xs:string'>
         <xs:enumeration value=''/>
       </xs:restriction>
     </xs:simpleType>

   </xs:schema>


B.2 jabber:iq:last

   <?xml version='1.0' encoding='UTF-8'?>
   <xs:schema
       xmlns:xs='http://www.w3.org/2001/XMLSchema'
       targetNamespace='jabber:iq:last'
       xmlns='jabber:iq:last'
       elementFormDefault='qualified'>

     <xs:element name='query'>
       <xs:complexType>
         <xs:attribute name='seconds'
                       type='xs:unsignedLong'
                       use='optional'/>
       </xs:complexType>
     </xs:element>

   </xs:schema>


B.3 jabber:iq:privacy

   <?xml version='1.0' encoding='UTF-8'?>
   <xs:schema



Saint-Andre & Miller    Expires December 3, 2003               [Page 78]


Internet-Draft           XMPP Instant Messaging                June 2003


       xmlns:xs='http://www.w3.org/2001/XMLSchema'
       targetNamespace='jabber:iq:privacy'
       xmlns='jabber:iq:privacy'
       elementFormDefault='qualified'>

     <xs:element name='query'>
       <xs:complexType>
         <xs:sequence>
           <xs:element ref='active'
                       minOccurs='0'
                       maxOccurs='1'/>
           <xs:element ref='default'
                       minOccurs='0'
                       maxOccurs='1'/>
           <xs:element ref='list'
                       minOccurs='0'
                       maxOccurs='unbounded'/>
         </xs:sequence>
       </xs:complexType>
     </xs:element>

     <xs:element name='active'>
       <xs:complexType>
         <xs:attribute name='name'
                       type='xs:string'
                       use='optional'/>
       </xs:complexType>
     </xs:element>

     <xs:element name='default'>
       <xs:complexType>
         <xs:attribute name='name'
                       type='xs:string'
                       use='optional'/>
       </xs:complexType>
     </xs:element>

     <xs:element name='list'>
       <xs:complexType>
         <xs:sequence>
           <xs:element ref='item'
                       minOccurs='0'
                       maxOccurs='unbounded'/>
         </xs:sequence>
         <xs:attribute name='name'
                       type='xs:string'
                       use='required'/>
       </xs:complexType>



Saint-Andre & Miller    Expires December 3, 2003               [Page 79]


Internet-Draft           XMPP Instant Messaging                June 2003


     </xs:element>

     <xs:element name='item'>
       <xs:complexType>
         <xs:sequence>
           <xs:element ref='iq'
                       minOccurs='0'
                       maxOccurs='1'/>
           <xs:element ref='message'
                       minOccurs='0'
                       maxOccurs='1'/>
           <xs:element ref='presence-in'
                       minOccurs='0'
                       maxOccurs='1'/>
           <xs:element ref='presence-out'
                       minOccurs='0'
                       maxOccurs='1'/>
         </xs:sequence>
         <xs:attribute name='order'
                       type='xs:nonNegativeInteger'
                       use='required'/>
         <xs:attribute name='value'
                       type='xs:string'
                       use='optional'/>
         <xs:attribute name='action' use='required'>
           <xs:simpleType>
             <xs:restriction base='xs:NCName'>
               <xs:enumeration value='allow'/>
               <xs:enumeration value='deny'/>
             </xs:restriction>
           </xs:simpleType>
         </xs:attribute>
         <xs:attribute name='type' use='optional'>
           <xs:simpleType>
             <xs:restriction base='xs:NCName'>
               <xs:enumeration value='group'/>
               <xs:enumeration value='jid'/>
               <xs:enumeration value='subscription'/>
             </xs:restriction>
           </xs:simpleType>
         </xs:attribute>
       </xs:complexType>
     </xs:element>

     <xs:element name='iq' type='empty'/>
     <xs:element name='message' type='empty'/>
     <xs:element name='presence-in' type='empty'/>
     <xs:element name='presence-out' type='empty'/>



Saint-Andre & Miller    Expires December 3, 2003               [Page 80]


Internet-Draft           XMPP Instant Messaging                June 2003


     <xs:simpleType name='empty'>
       <xs:restriction base='xs:string'>
         <xs:enumeration value=''/>
       </xs:restriction>
     </xs:simpleType>

   </xs:schema>


B.4 jabber:iq:roster

   <?xml version='1.0' encoding='UTF-8'?>
   <xs:schema
       xmlns:xs='http://www.w3.org/2001/XMLSchema'
       targetNamespace='jabber:iq:roster'
       xmlns='jabber:iq:roster'
       elementFormDefault='qualified'>

     <xs:element name='query'>
       <xs:complexType>
         <xs:sequence>
           <xs:element ref='item'
                       minOccurs='0'
                       maxOccurs='unbounded'/>
         </xs:sequence>
       </xs:complexType>
     </xs:element>

     <xs:element name='item'>
       <xs:complexType>
         <xs:sequence>
           <xs:element ref='group'
                       minOccurs='0'
                       maxOccurs='unbounded'/>
         </xs:sequence>
         <xs:attribute name='jid' type='xs:string' use='required'/>
         <xs:attribute name='name' type='xs:string' use='optional'/>
         <xs:attribute name='subscription' use='optional'>
           <xs:simpleType>
             <xs:restriction base='xs:NCNAME'>
               <xs:enumeration value='to'/>
               <xs:enumeration value='from'/>
               <xs:enumeration value='both'/>
               <xs:enumeration value='none'/>
               <xs:enumeration value='remove'/>
             </xs:restriction>
           </xs:simpleType>
         </xs:attribute>



Saint-Andre & Miller    Expires December 3, 2003               [Page 81]


Internet-Draft           XMPP Instant Messaging                June 2003


         <xs:attribute name='ask' use='optional'>
           <xs:simpleType>
             <xs:restriction base='xs:NCNAME'>
               <xs:enumeration value='subscribe'/>
             </xs:restriction>
           </xs:simpleType>
         </xs:attribute>
       </xs:complexType>
     </xs:element>

     <xs:element name='group' type='xs:string'/>

   </xs:schema>






































Saint-Andre & Miller    Expires December 3, 2003               [Page 82]


Internet-Draft           XMPP Instant Messaging                June 2003


Appendix C. Revision History

   Note to RFC Editor: please remove this entire appendix, and the
   corresponding entries in the table of contents, prior to publication.

C.1 Changes from draft-ietf-xmpp-im-11

   o  Further clarified subscription syntax and semantics.

   o  Further clarified presence responsibilities for clients and
      servers.

   o  Added 'xml:lang' example to presence status.

   o  Added subsection on presence priority.

   o  Defined server handling of unsolicited presence stanzas of type
      "subscribed".

   o  Specified default resource priority if not provided.

   o  Corrected several errors in the schemas.

   o  Added privacy list business rule regarding roster changes.

   o  Removed the 'jabber:iq:privacy:error' namespace (not necessary).

   o  Documented message type='normal'.

   o  Made numerous small editorial changes throughout.


C.2 Changes from draft-ietf-xmpp-im-10

   o  Clarified presence responsibilities for servers and clients.

   o  Clarified the routing and delivery rules for servers.

   o  Made the 'xml:lang' examples more complete.

   o  Corrected several errors in the unsubscribe workflow.

   o  Made small editorial changes in several sections.


C.3 Changes from draft-ietf-xmpp-im-09

   o  Clarified rules regarding allowable JID types in rosters.



Saint-Andre & Miller    Expires December 3, 2003               [Page 83]


Internet-Draft           XMPP Instant Messaging                June 2003


   o  Further clarified the semantics and routing implications of
      presence priorities.

   o  Removed several obsolete subsections.


C.4 Changes from draft-ietf-xmpp-im-08

   o  Removed authorization content (now addressed in XMPP Core).

   o  Added protocol for initiating an IM session, including schema and
      IANA registration template.

   o  Corrected <*-condition/> elements to be <condition/>.

   o  Made small editorial changes to address RFC Editor requirements.


C.5 Changes from draft-ietf-xmpp-im-07

   o  Added several error cases for resource authorization and updated
      relevant schema.


C.6 Changes from draft-ietf-xmpp-im-06

   o  Specified that IQ result stanzas are required in response to
      roster pushes.

   o  Changed stanza error namespace names to conform to the format
      defined in "The IETF XML Registry" as specified in XMPP Core.

   o  Removed note to RFC Editor regarding provisional namespace names.


C.7 Changes from draft-ietf-xmpp-im-05

   o  Removed use of ask='unsubscribe' per list discussion.

   o  Clarified handling of resource conflict during authorization.

   o  Added schemas for jabber:iq:auth, jabber:iq:auth:error, and
      jabber:iq:privacy:error.

   o  Corrected several small protocol errors in the examples.

   o  Clarified semantics of message types.




Saint-Andre & Miller    Expires December 3, 2003               [Page 84]


Internet-Draft           XMPP Instant Messaging                June 2003


C.8 Changes from draft-ietf-xmpp-im-04

   o  Specified sending of unavailable presence after unsubscribe and
      subscription-cancellation actions.

   o  Further specified syntax and business rules for privacy lists.

   o  Brought error codes into line with definitions in
      draft-ietf-xmpp-core.

   o  Added note to RFC Editor regarding provisional namespace names.

   o  Removed vCard content and DTD, instead pointing to JSF
      documentation.


C.9 Changes from draft-ietf-xmpp-im-03

   o  Fixed order processing on privacy rules per list discussion.

   o  Made numerous small editorial changes.


C.10 Changes from draft-ietf-xmpp-im-02

   o  Added a great deal more detail to the narrative regarding
      server-side privacy rules as well as the interaction between
      rosters and subscriptions.

   o  Removed DTDs in favor of schemas (with the exception of vCard
      XML).

   o  Removed non-normative documentation of authentication using
      jabber:iq:auth and of in-band registration using
      jabber:iq:register, since these are maintained by the Jabber
      Software Foundation and are not part of the XMPP specification.


C.11 Changes from draft-ietf-xmpp-im-01

   o  Made numerous small editorial changes.


C.12 Changes from draft-ietf-xmpp-im-00

   o  Moved registration and authentication via jabber:iq:auth to
      non-normative appendices.




Saint-Andre & Miller    Expires December 3, 2003               [Page 85]


Internet-Draft           XMPP Instant Messaging                June 2003


   o  Changed initial presence stanza from MUST be empty to SHOULD be
      empty.

   o  Specified that user or clients should not send presence stanzas of
      type='probe'.

   o  Specified the algorithm for digest passwords.


C.13 Changes from draft-miller-xmpp-im-02

   o  Added information about the 'jabber:iq:last' protocol to meet the
      requirement defined in section 3.2.4 of RFC 2779.

   o  Added information about the 'jabber:iq:privacy' protocol to meet
      the requirement defined in section 2.3.5 of RFC 2779.

   o  Added information about the vCard XML protocol to meet the
      requirement defined in sections 3.1.3 and 4.1.4 of RFC 2779.

   o  Changed the material describing authentication (but not resource
      authorization) with 'jabber:iq:auth' to non-normative.

   o  Noted that the only watchers are subscribers.

   o  Nomenclature changes: (1) from "chunks" to "stanzas"; (2) from
      "host" to "server"; (3) from "node" to "client" or "user" (as
      appropriate).























Saint-Andre & Miller    Expires December 3, 2003               [Page 86]


Internet-Draft           XMPP Instant Messaging                June 2003


Intellectual Property Statement

   The IETF takes no position regarding the validity or scope of any
   intellectual property or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; neither does it represent that it
   has made any effort to identify any such rights. Information on the
   IETF's procedures with respect to rights in standards-track and
   standards-related documentation can be found in BCP-11. Copies of
   claims of rights made available for publication and any assurances of
   licenses to be made available, or the result of an attempt made to
   obtain a general license or permission for the use of such
   proprietary rights by implementors or users of this specification can
   be obtained from the IETF Secretariat.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights which may cover technology that may be required to practice
   this standard. Please address the information to the IETF Executive
   Director.


Full Copyright Statement

   Copyright (C) The Internet Society (2003). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assignees.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION



Saint-Andre & Miller    Expires December 3, 2003               [Page 87]


Internet-Draft           XMPP Instant Messaging                June 2003


   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.











































Saint-Andre & Miller    Expires December 3, 2003               [Page 88]