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Versions: 00 01 02 03 04 05 rfc4826                                     
SIMPLE                                                      J. Rosenberg
Internet-Draft                                               dynamicsoft
Expires: April 26, 2004                                 October 27, 2003


   An Extensible Markup Language (XML) Configuration Access Protocol
                    (XCAP) Usage for Resource Lists
                  draft-ietf-simple-xcap-list-usage-01

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 April 26, 2004.

Copyright Notice

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

Abstract

   This document describes a usage of the Extensible Markup Language
   (XML) Configuration Access Protocol (XCAP) for manipulating lists of
   resources. These lists can be used as presence lists (also known as
   buddy lists or rosters), but this specification does not restrict
   their usage to that.










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Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.   Terminology  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.   Application Unique ID  . . . . . . . . . . . . . . . . . . .   5
   4.   Structure of a Resource List . . . . . . . . . . . . . . . .   6
   5.   Resource Interdependencies . . . . . . . . . . . . . . . . .   8
   6.   Additional Constraints . . . . . . . . . . . . . . . . . . .   9
   7.   Naming Conventions . . . . . . . . . . . . . . . . . . . . .  10
   8.   Authorization Policies . . . . . . . . . . . . . . . . . . .  11
   9.   XML Schema . . . . . . . . . . . . . . . . . . . . . . . . .  12
   10.  Example Document . . . . . . . . . . . . . . . . . . . . . .  14
   11.  Security Considerations  . . . . . . . . . . . . . . . . . .  15
   12.  IANA Considerations  . . . . . . . . . . . . . . . . . . . .  16
   12.1 XCAP Application Usage ID  . . . . . . . . . . . . . . . . .  16
   12.2 application/resource-lists+xml MIME Type . . . . . . . . . .  16
   12.3 URN Sub-Namespace Registration for
        urn:ietf:params:xml:ns:resource-lists  . . . . . . . . . . .  17
        Normative References . . . . . . . . . . . . . . . . . . . .  18
        Informative References . . . . . . . . . . . . . . . . . . .  19
        Author's Address . . . . . . . . . . . . . . . . . . . . . .  19
        Intellectual Property and Copyright Statements . . . . . . .  20





























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1. Introduction

   In many communications applications, it is neccesary for the network
   to have access to a list of resources that represent a group that the
   user would like to apply an action to. One such example is a presence
   list [13]. These lists are used by Session Initiation Protocol (SIP)
   for Instant Messaging and  Presence (SIMPLE) [9]Resource List Servers
   (RLS) [11] for processing list subscriptions. Another example might
   be list of recipients for an instant message, or a list of users to
   invite to a conference bridge.

   Generally, these lists will need to be manipulated by the end users
   of the system, and used by servers in the network. To support such
   manipulations, the XML Configuration Access Protocol (XCAP) [7] has
   been defined. XCAP requires application usages to standardize several
   pieces of information, including an application unique ID (AUID), an
   XML schema, and various other pieces of information. This
   specification fulfills those requirements.

   The XML schema defined here has several other usages outside of XCAP:

   1.  A PC client application will need to know the users in the
       presence list, so that it can generate a subscription to each
       one. This information represents user provisioned data for the
       application. Typically, this information is stored on local disk
       in a proprietary file format. By defining a standard format, the
       same list can be used by a multiplicity of different client
       applications, providing portability across them.

   2.  It is common for users to share presence lists. As an example,
       user A may have three people in their list that they wish to tell
       user B about. User A would like to send an email to user B with
       an attachment describing these three people. Should user B open
       the attachment, the three people can be added to their own
       presence list. Doing this requires a standardized format for
       exchanging lists over email, instant messaging, and other
       communications protocols.














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2. Terminology

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
   indicate requirement levels for compliant implementations.













































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3. Application Unique ID

   XCAP requires application usages to define a unique application usage
   ID (AUID) in either the IETF tree or a vendor tree. This
   specification defines the "resource-lists" AUID within the IETF tree,
   via the IANA registration in Section 12.













































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4. Structure of a Resource List

   A resource list is an XML [2] document that MUST be well-formed and
   SHOULD be valid. Resource list documents MUST be based on XML 1.0 and
   MUST be encoded using UTF-8. This specification makes use of XML
   namespaces for identifying resource list documents and document
   fragments. The namespace URI for elements defined by this
   specification is a URN [3], using the namespace identifier 'ietf'
   defined by [5] and extended by [6]. This URN is:

      urn:ietf:params:xml:ns:resource-lists

   A resource list document begins with the root element tag
   ``resource-lists''.  It consists of any number of ``list''
   sub-elements, each of which is a resource list. Other elements from
   different namespaces MAY be present for the purposes of
   extensibility; elements or attributes from unknown namespaces MUST be
   ignored. There are three attributes associated with this element. The
   first, "name", MUST be present:

      name: This attribute is a descriptive name for the list. It MUST
      be unique amongst all other list elements within the same parent
      element.

   Each list element will also have boolean attributes which indicate a
   specific action that may be made against that list. This
   specification defines a single attribute - subscribeable - which
   indicates that the list may be subscribed to using the SIP event list
   specification [11]. Extensions to this application usage MAY define
   additional boolean elements, each within a different namespace, for
   the purposes of indicating other actions that may be peformed. When
   an attribute is absent, it implies that the operation is not
   supported.

   The third other attribute, "uri" MAY be present. It provides a URI
   that can be used to access the list, for example, using the SIP event
   notification extension for lists [11]. As a result, the URI MUST be
   either a SIP URI or a pres URI [12].

   Each list element is composed of a sequence of entry elements, list
   elements, external elements. The ability of a list element to contain
   other list elements means that a resource list can be hierarchically
   structured. An entry element describes a single presentity that is
   part of the list. An external element contains a reference to a list
   stored on another server. A list element can also contain elements
   from other namespaces, for the purposes of extensibility.

   The entry element describes a single resource. The entry element has



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   two attributes:

      name: This mandatory attribute is a unique identifier amongst all
      other entry elements of the same parent.

      uri: This optional attribute is a URI that is used to access the
      resource. It MUST be either a SIP or pres URI.

   The entry element contains a sequence of other elements. Only one
   such element is defined at this time, which is the display-name. This
   element provides a UTF-8 encoded string, meant for consumption by the
   user, that describes the resource. Unlike the "name" attribute of the
   entry element, the display-name has no uniqueness requirements. Other
   elements from other namespaces MAY be included. This is meant to
   support the inclusion of other information about the entry, such as a
   phone number or postal address.



































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5. Resource Interdependencies

   An XCAP server supporting this application usage need only worry
   about a single data interdependency - the "uri" attribute of the list
   element.

   If the "uri" attribute is absent in a document written to an XCAP
   server, but the "subscribeable" flag is true, the XCAP server MUST
   allocate a URI for this list. This allocated URI MUST be globally
   unique, and MUST route to an RLS which will handle list subscriptions
   for the list defined by the document. The server MUST set the uri
   attribute of the document with this URI.

   A server MUST NOT delete the "uri" attribute, however, should a
   client change the subscribeable flag to false after the server has
   allocated a URI.



































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6. Additional Constraints

   There are no constraints on the document beyond those described in
   the schema.















































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7. Naming Conventions

   There are no naming conventions that need to be defined for this
   application usage. A subscription to a resource list will be to a
   specific URI. That URI will be one of the "uri" attributes defined in
   a list within one of the documents managed by an XCAP server.













































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8. Authorization Policies

   This application usage does not modify the default XCAP authorization
   policy, which is that only a user can read, write or modify their own
   documents. A server can allow priveleged users to modify documents
   that they don't own, but the establishment and indication of such
   policies is outside the scope of this document. It is anticipated
   that a future application usage will define which users are allowed
   to modify a list resource.










































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9. XML Schema

   The following is the XML schema definition of the resource list:


   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema targetNamespace="urn:ietf:params:xml:ns:resource-lists"
     xmlns:xs="http://www.w3.org/2001/XMLSchema"
     xmlns="urn:ietf:params:xml:ns:resource-lists"
     elementFormDefault="qualified" attributeFormDefault="unqualified">
     <xs:element name="resource-lists">
       <xs:complexType>
         <xs:sequence>
           <xs:element name="list" type="listType" minOccurs="0"
             maxOccurs="unbounded"/>
         </xs:sequence>
       </xs:complexType>
     </xs:element>
     <xs:complexType name="listType">
       <xs:sequence maxOccurs="unbounded">
         <xs:choice>
           <xs:element name="list" minOccurs="0" maxOccurs="unbounded">
             <xs:complexType>
               <xs:complexContent>
                 <xs:extension base="listType"/>
               </xs:complexContent>
             </xs:complexType>
           </xs:element>
           <xs:element name="external" type="xs:anyURI" minOccurs="0"
             maxOccurs="unbounded"/>
           <xs:element name="entry" type="entryType" minOccurs="0"
             maxOccurs="unbounded"/>
           <xs:any namespace="##other" processContents="lax"
             minOccurs="0"  maxOccurs="unbounded"/>
         </xs:choice>
       </xs:sequence>
       <xs:attribute name="name" type="xs:string" use="required"/>
       <xs:attribute name="uri" type="xs:anyURI" use="optional"/>
       <xs:attribute name="subscribeable" type="xs:boolean" use="optional"/>
       <xs:anyAttribute namespace="##other"/>
     </xs:complexType>
     <xs:complexType name="entryType">
       <xs:sequence>
         <xs:element name="display-name" type="display-nameType"/>
         <xs:any namespace="##other" processContents="lax"
            minOccurs="0" maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute name="name" type="xs:string" use="required"/>



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       <xs:attribute name="uri" type="xs:anyURI" use="optional"/>
     </xs:complexType>
     <xs:simpleType name="display-nameType">
       <xs:restriction base="xs:string"/>
     </xs:simpleType>
   </xs:schema>













































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10. Example Document

   The following is an example of a document compliant to the schema:


   <?xml version="1.0" encoding="UTF-8"?>
   <resource-lists xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
     <list name="friends" uri="sip:friends@example.com" subscribeable="true">
       <entry name="Bill" uri="sip:bill@example.com">
         <display-name>Bill Doe</display-name>
       </entry>
       <list name="close-friends" uri="sip:close-friends@example.com"
             subscribeable="true">
         <entry name="Joe" uri="sip:joe@example.com">
           <display-name>Joe Smith</display-name>
         </entry>
         <entry name="Nancy" uri="sip:nancy@example.com">
           <display-name>Nancy Gross</display-name>
         </entry>
         <external>http://www.example.org/xcap/resource-lists/users/a/foo
            </external>
       </list>
     </list>
   </resource-lists>

   TODO: formally validate against schema.

























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11. Security Considerations

   The configuration information defined by this application usage is
   particularly sensitive. It represents the principle set of people
   with whom a user would like to communicate. As a result, clients
   SHOULD use TLS when contacting servers in order to fetch this
   information. Note that this does not represent a change in
   requirement strength from XCAP.











































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12. IANA Considerations

   There are several IANA considerations associated with this
   specification.

12.1 XCAP Application Usage ID

   This section registers a new XCAP Application Usage ID (AUID)
   according to the IANA procedures defined in [7].

      Name of the AUID: resource-lists

      Description: A resource list application is any application that
      needs access to a list of resources, identified by a URI, to which
      operations, such as subscriptions, can be applied.


12.2 application/resource-lists+xml MIME Type

      MIME media type name: application

      MIME subtype name: resource-lists+xml

      Mandatory parameters: none

      Optional parameters: Same as charset parameter application/xml as
      specified in RFC 3023 [4].

      Encoding considerations: Same as encoding considerations of
      application/xml as specified in RFC 3023 [4].

      Security considerations: See Section 10 of RFC 3023 [4] and
      Section 11 of this specification.

      Interoperability considerations: none.

      Published specification: This document.

      Applications which use this media type: This document type has
      been used to support subscriptions to lists of users [11] for
      SIP-based presence [9].

      Additional Information:

         Magic Number: None






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         File Extension: .rl or .xml

         Macintosh file type code: "TEXT"

         Personal and email address for further information: Jonathan
         Rosenberg, jdrosen@jdrosen.net

         Intended usage: COMMON

         Author/Change controller: The IETF.


12.3 URN Sub-Namespace Registration for
     urn:ietf:params:xml:ns:resource-lists

   This section registers a new XML namespace, as per the guidelines in
   [6]

      URI: The URI for this namespace is
      urn:ietf:params:xml:ns:resource-lists.

      Registrant Contact: IETF, SIMPLE working group, (simple@ietf.org),
      Jonathan Rosenberg (jdrosen@jdrosen.net).

      XML:


                BEGIN
                <?xml version="1.0"?>
                <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
                          "http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
                <html xmlns="http://www.w3.org/1999/xhtml">
                <head>
                  <meta http-equiv="content-type"
                     content="text/html;charset=iso-8859-1"/>
                  <title>Resource Lists Namespace</title>
                </head>
                <body>
                  <h1>Namespace for Resource Lists</h1>
                  <h2>application/resource-lists+xml</h2>
                  <p>See <a href="[[[URL of published RFC]]]">RFCXXXX</a>.</p>
                </body>
                </html>
                END







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Normative References

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

   [2]  Bray, T., Paoli, J., Sperberg-McQueen, C. and E. Maler,
        "Extensible Markup Language (XML) 1.0 (Second Edition)", W3C REC
        REC-xml-20001006, October 2000.

   [3]  Moats, R., "URN Syntax", RFC 2141, May 1997.

   [4]  Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC
        3023, January 2001.

   [5]  Moats, R., "A URN Namespace for IETF Documents", RFC 2648,
        August 1999.

   [6]  Mealling, M., "The IETF XML Registry",
        draft-mealling-iana-xmlns-registry-05 (work in progress), June
        2003.

   [7]  Rosenberg, J., "The Extensible Markup Language (XML)
        Configuration Access Protocol  (XCAP)",
        draft-ietf-simple-xcap-00 (work in progress), June 2003.



























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Informative References

   [8]   Day, M., Rosenberg, J. and H. Sugano, "A Model for Presence and
         Instant Messaging", RFC 2778, February 2000.

   [9]   Rosenberg, J., "A Presence Event Package for the Session
         Initiation Protocol (SIP)", draft-ietf-simple-presence-10 (work
         in progress), January 2003.

   [10]  Roach, A., "Session Initiation Protocol (SIP)-Specific Event
         Notification", RFC 3265, June 2002.

   [11]  Roach, A., Rosenberg, J. and B. Campbell, "A Session Initiation
         Protocol (SIP) Event Notification Extension for  Resource
         Lists", draft-ietf-simple-event-list-04 (work in progress),
         June 2003.

   [12]  Peterson, J., "Common Profile for Presence (CPP)",
         draft-ietf-impp-pres-04 (work in progress), October 2003.

   [13]  Rosenberg, J. and M. Isomaki, "Requirements for Manipulation of
         Data Elements in Session Initiation  Protocol (SIP) for Instant
         Messaging and Presence Leveraging Extensions (SIMPLE) Systems",
         draft-ietf-simple-data-req-03 (work in progress), June 2003.


Author's Address

   Jonathan Rosenberg
   dynamicsoft
   600 Lanidex Plaza
   Parsippany, NJ  07052
   US

   Phone: +1 973 952-5000
   EMail: jdrosen@dynamicsoft.com
   URI:   http://www.jdrosen.net














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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
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   The IETF invites any interested party to bring to its attention any
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   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
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   The limited permissions granted above are perpetual and will not be
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   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



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   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.











































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