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Versions: 00 01 02 03 04 05 06                           Standards Track
Internet Printing Protocol WG                                 Hugo Parra
INTERNET-DRAFT                                              Novell, Inc.
<draft-ietf-ipp-indp-method-06.txt>                         Tom Hastings
Updates:  RFC 2910 and 2911                                  Xerox Corp.
[Target Category:  standards track]                        July 17, 2001
Expires:  January 17, 2002



                     Internet Printing Protocol (IPP):
    The 'indp' Delivery Method for Event Notifications and Protocol/1.0

      Copyright (C) The Internet Society (2001). All Rights Reserved.

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 as
   http://www.ietf.org/shadow.html.

Abstract

   This document describes an extension to the Internet Printing
   Protocol/1.0 (IPP) [RFC2566, RFC2565] and IPP/1.1 [RFC2911, RFC2910].
   This document specifies the 'indp' Delivery Method and Protocol/1.0
   for use with the "IPP Event Notifications and Subscriptions"
   specification [ipp-ntfy].  When IPP Notification [ipp-ntfy] is
   supported, the Delivery Method defined in this document is one of the
   RECOMMENDED Delivery Methods for Printers to support.

   This Delivery Method is a simple protocol consisting of a single
   operation:  the Send-Notifications operation which uses the same
   encoding and transport as IPP [RFC2565, RFC2910].  For this Delivery
   Method, when an Event occurs, the Printer immediately sends (pushes)
   an Event Notification via the Send-Notifications operation to the

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   Notification Recipient specified in the Subscription Object.  The
   Event Notification content consists of Machine Consumable attributes
   and a Human Consumable "notify-text" attribute.  The Notification
   Recipient returns a response to the Printer.













































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Table of Contents


   1 Introduction.....................................................5

   2 Terminology......................................................6

   3 Model and Operation..............................................6

   4 General Information..............................................7

   5 Subscription object attributes..................................10
   5.1 Subscription Template Attribute Conformance...................10
   5.2 Additional Information about Subscription Template Attributes.10
   5.2.1 notify-recipient-uri (uri)..................................10
   5.3 Subscription Description Attribute Conformance................10

   6 New Values for Existing Printer Description Attributes..........11
   6.1 notify-schemes-supported (1setOf uriScheme)...................11
   6.2 operations-supported (1setOf type2 enum)......................11

   7 Attributes Only in Event Notifications..........................11

   8 Operations for Notification.....................................12
   8.1 Send-Notifications operation..................................12
   8.1.1 Send-Notifications Request..................................12
   8.1.2 Send-Notifications Response.................................17

   9 Status Codes....................................................18
   9.1 Additional Status Codes.......................................18
   9.1.1 successful-ok-ignored-notifications (0x0004)................19
   9.1.2 client-error-ignored-all-notifications (0x0416).............19
   9.2 Status Codes returned in Event Notification Attributes Groups.19
   9.2.1 client-error-not-found (0x0406).............................19
   9.2.2 successful-ok-but-cancel-subscription (0x0006)..............20

   10 Encoding and Transport.........................................20
   10.1 Encoding of the Operation Layer..............................20
   10.2 Encoding of Transport Layer..................................20

   11 Conformance Requirements.......................................20
   11.1 Conformance Requirements for Printers........................21
   11.2 Conformance Requirements for INDP Notification Recipients....21

   12 INDP URL Scheme................................................22
   12.1 INDP URL Scheme Applicability and Intended Usage.............22

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   12.2 INDP URL Scheme Associated INDP Port.........................22
   12.3 INDP URL Scheme Associated MIME Type.........................22
   12.4 INDP URL Scheme Character Encoding...........................22
   12.5 INDP URL Scheme Syntax in ABNF...............................23
   12.5.1 INDP URL Examples..........................................23
   12.5.2 INDP URL Comparisons.......................................24

   13 IANA Considerations............................................24
   13.1 Operation Registrations......................................25
   13.2 Additional attribute value registrations for existing attributes
         25
   13.2.1 Additional values for the "notify-schemes-supported" Printer
              attribute..............................................25
   13.2.2 Additional values for the "operations-supported" Printer
              attribute..............................................26
   13.3 Status code Registrations....................................26

   14 Internationalization Considerations............................26

   15 Security Considerations........................................27
   15.1 Security Conformance.........................................27

   16 References.....................................................28

   17 Author's Addresses.............................................29

   18 Summary of Base IPP documents..................................30

   19 Full Copyright Statement.......................................32


Tables

   Table 1 - Information about the Delivery Method....................8
   Table 2 - Operation-id assignments................................11
   Table 3 - Attributes in Event Notification Content................15
   Table 4 - Additional Attributes in Event Notification Content for Job
      Events ........................................................16
   Table 5 - Combinations of Events and Subscribed Events for "job-
      impressions-completed" ........................................16
   Table 6 - Additional Attributes in Event Notification Content for
      Printer Events ................................................17
   Table 7 - The "event-notification-attributes-tag" value...........20






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1 Introduction

   The "IPP Event Notifications and Subscriptions" document [ipp-ntfy]
   defines an OPTIONAL extension to Internet Printing Protocol/1.0 (IPP)
   [RFC2566, RFC2565] and IPP/1.1 [RFC2911, RFC2910]  (for a description
   of the base IPP documents, see section 18).  That extension defines
   operations that a client can perform in order to create Subscription
   Objects in a Printer and carry out other operations on them.  A
   Subscription Object represents a Subscription abstraction.  A client
   associates Subscription Objects with a particular Job by performing
   the Create-Job-Subscriptions operation or by submitting a Job with
   subscription information.  A client associates Subscription Objects
   with the Printer by performing a Create-Printer-Subscriptions
   operation.  Four other operations are defined for Subscription
   Objects: Get-Subscriptions-Attributes, Get-Subscriptions, Renew-
   Subscription, and Cancel-Subscription.  The Subscription Object
   specifies that when one of the specified Events occurs, the Printer
   sends an asynchronous Event Notification to the specified
   Notification Recipient via the specified Delivery Method (i.e.,
   protocol).

   The "IPP Event Notifications and Subscriptions" document [ipp-ntfy]
   specifies that each Delivery Method is defined in another document.
   This document is one such document, and it specifies the 'indp'
   Delivery Method.  When IPP Notification [ipp-ntfy] is supported, the
   Delivery Method defined in this document is one of the RECOMMENDED
   Delivery Methods for Printers to support.  This Delivery Method is a
   simple protocol consisting of a single operation: the Send-
   Notifications operation which uses the same encoding and transport as
   IPP.  This document defines version '1.0' of the protocol.

   For the 'indp' Delivery Method, an IPP Printer sends (pushes) a Send-
   Notifications operation request containing one or more Event
   Notifications to  the Notification Recipient specified in the
   Subscription Object.  The Event Notification content consists of
   Machine Consumable attributes and a Human Consumable "notify-text"
   attribute.

   The Notification Recipient receives the Event Notification as a Send-
   Notifications operation, in the same way as an IPP Printer receives
   IPP operations.  The Notification Recipient returns a response to the
   Printer.




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2 Terminology

   This section defines the following terms that are used throughout
   this document:

      This document uses the same terminology as [RFC2911], such as
      "client", "Printer", "attribute", "attribute value", "keyword",
      "operation", "request", "response", and "support".

      Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD,
      SHOULD NOT, MAY, NEED NOT, and OPTIONAL, have special meaning
      relating to conformance as defined in RFC 2119 [RFC2119] and
      [RFC2911] section 12.1.  If an implementation supports the
      extension defined in this document, then these terms apply;
      otherwise, they do not.  These terms define conformance to this
      document only; they do not affect conformance to other documents,
      unless explicitly stated otherwise.

      Event Notification Attributes Group - The attributes group in a
            request that contains Event Notification Attributes in a
            request or response.

      Other capitalized terms, such as Notification Recipient, Event
      Notification, Compound Event Notification, Printer, etc.,  are
      defined in [ipp-ntfy], have the same meanings, and are not
      reproduced here.


3 Model and Operation

   See [ipp-ntfy] for the description of the Event Notification Model
   and Operation.  This Delivery Method takes advantage of combining
   several Event Notifications into a single Compound Event Notification
   that is delivery by a single Send-Notification operation to a single
   Notification Recipient.

   When creating each Subscription object, the client supplies the
   "notify-recipient" (uri) Subscription Template attribute.  The
   "notify-recipient" attribute specifies both a single Notification
   Recipient that is to receive the Notifications when subsequent events
   occur and the method for notification delivery that the IPP Printer
   is to use.  For the Notification Delivery Method defined in this
   document, the notification method is 'indp' and the rest of the URI
   is the address of the Notification Recipient to which the IPP Printer
   will send the Send-Notifications operation.

   The 'indp' Notification Delivery Method defined in this document uses
   a client/server protocol paradigm.  The "client" in this relationship

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   is the Printer described in [ipp-ntfy] while the "server" is the
   Notification Recipient. The Printer invokes the Send-Notifications
   operation to communicate IPP Event Notification contents to the
   Notification Recipient. The Notification Recipient only conveys
   information to the Printer in the form of responses to the operations
   initiated by the Printer.

   Printers that implement the 'indp' Notification Delivery Method will
   need to include an HTTP client stack while Notification Recipients
   that implement this Delivery Method will need to support an HTTP
   server stack.  See section 10.2 for more details.

   If the client wants the Printer to send Event Notifications via the
   'indp' Delivery Method, the client MUST choose a value for "notify-
   recipient-uri" attribute which conforms to the rules of section
   5.2.1.

   When an Event occurs, the Printer MUST immediately:

   1.Find all pertinent Subscription Objects P according to the rules of
      section 9 of [ipp-ntfy], AND

   2.Find the subset M of these Subscription Objects P whose "notify-
      recipient-uri" attribute has a scheme value of 'indp', AND

   3.For each Subscription Object in M, the Printer MUST

     a)generate a Send-Notifications request as specified in section
       8.1.1 AND

     b)send the Send-Notifications request to the Notification
       Recipient specified by the address part of the "notify-
       recipient-uri" attribute value (see section 5.2.1).

   If several events occur sufficiently close to one another for the
   same or different Subscription objects, but with the same
   Notification Recipient, the Printer MAY combine them into a single
   Send-Notifications request using a separate Event Notification
   Attributes group for each event (see section 8.1.1).


4 General Information

   If a client or Printer supports this Delivery Method, Table 1 lists
   its characteristics.




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              Table 1 - Information about the Delivery Method


   Document Method conformance        'indp' realization
   requirement


   1.  What is the URL scheme name    indp
       for the Delivery Method?

   2.  Is the Delivery Method is
       REQUIRED, RECOMMENDED, or
       OPTIONAL for an IPP Printer to
       support?                       RECOMMENDED

   3.  What transport and delivery
       protocol does the Printer use  complete HTTP/1.1 stack
       to deliver the Event           [RFC2616]
       Notification content, i.e.,
       what is the entire network
       stack?                         A Printer MUST support a

   4.  Can several Event              A Printer implementation MAY
       Notifications be combined into combine several Event
       a Compound Event Notification? Notifications into a single
                                      Event Notifications request as
                                      separate Event Notification
                                      Attributes Groups, see section
                                      8.1.1

   5.  Is the Delivery Method         This Delivery Method is a push.
       initiated by the Notification
       Recipient (pull), or by the
       Printer (push)?

   6.  Is the Event Notification      Machine Consumable with the
       content Machine Consumable or  "notify-text" attribute being
       Human Consumable?              Human Consumable

   7.  What section in this document  The representation and encoding
       answers the following          is the same as IPP.  See
       question? For a Machine        section 8.1.1
       Consumable Event Notification,
       what is the representation and
       encoding of values defined in
       section 9.1 of [ipp-ntfy] and
       the conformance requirements
       thereof? For a Human

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   Document Method conformance        'indp' realization
   requirement


       thereof? For a Human
       Consumable Event Notification,
       what is the representation and
       encoding of pieces of
       information defined in section
       9.2 of [ipp-ntfy] and the
       conformance requirements
       thereof?

   8.  What are the latency and
       reliability of the transport   itself (see [RFC2911]).
       and delivery protocol?         Same as for IPP/1.0 or IPP/1.1

   9.  What are the security aspects  See section 15
       of the transport and delivery
       protocol, e.g., how it is
       handled in firewalls?

   10. What are the content length    They are the same as for
       restrictions?                  IPP/1.0 and IPP/1.1 itself (see
                                      [RFC2911]).

   11. What are the additional values A new Event Notifications
       or pieces of information that  attribute group (see section
       a Printer sends in an Event    10.1) and additional status
       Notification and the           codes for use in the response
       conformance requirements       (see section 9)
       thereof?

   12. What are the additional        None
       Subscription Template and/or
       Subscription Description
       attributes and the conformance
       requirements thereof?

   13. What are the additional        None
       Printer Description attributes
       and the conformance
       requirements thereof?


   The remaining sections of this document parallel the sections of
   [ipp-ntfy].

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5 Subscription object attributes

   This section defines the Subscription object conformance requirements
   for Printers.


5.1 Subscription Template Attribute Conformance

   The 'indp' Delivery Method has the same conformance requirements for
   Subscription Template attributes as defined in [ipp-ntfy].  The
   'indp' Delivery Method does not define any addition Subscription
   Template attributes.


5.2 Additional Information about Subscription Template Attributes

   This section defines additional information about Subscription
   Template attributes defined in [ipp-ntfy].


5.2.1 notify-recipient-uri (uri)

   This section describes the syntax of the value of this attribute for
   the 'indp' Delivery Method. The syntax for values of this attribute
   for other Delivery Method is defined in other Delivery Method
   Documents.

   In order to support the 'indp' Delivery Method and Protocol, the
   Printer MUST support the following syntax:

          The 'indp://' URI scheme.  The remainder of the URI indicates
          the host name or host address (and optional path) of the
          Notification Recipient that is to receive the Send-
          Notification operation.  See section 12 for a complete
          definition of the syntax of the INDP URL.


5.3 Subscription Description Attribute Conformance

   The 'indp' Delivery Method has the same conformance requirements for
   Subscription Description attributes as defined in [ipp-ntfy].  The
   'indp' Delivery Method does not define any addition Subscription
   Description attributes.






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6 New Values for Existing Printer Description Attributes

   This Delivery Method does not define any additional Printer
   Description attribute from those defined in [ipp-ntfy].  However, it
   does define additional values for existing Printer Description
   attributes defined in [ipp-ntfy].  This section defines those
   additional values.


6.1 notify-schemes-supported (1setOf uriScheme)

   The following value of the "notify-schemes-supported" Printer
   attribute (see [ipp-ntfy] section 5.3.1) is added in order to support
   the new Delivery Method defined in this document:

      'indp'  - The IPP Notification Delivery Method defined in this
        document.

6.2 operations-supported (1setOf type2 enum)

   Table 2 lists the value of the "operation-id" operation parameter
   (see [RFC2911]) and the value of the "operations-supported" Printer
   Description attribute (see [RFC2911]) added in order to support the
   new operation defined in this document.  The operation-id is assigned
   in the same name space as other operations that a Printer supports.
   However, a Printer MUST NOT include this value in its "operations-
   supported" attribute unless it can accept the Send-Notifications
   request.

                    Table 2 - Operation-id assignments


     Value        Operation Name


     0x001D       Send-Notifications




7 Attributes Only in Event Notifications

   No additional attributes are defined only for use in Event
   Notifications besides those defined in [ipp-ntfy].





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8 Operations for Notification

   This section defines the operation for Event Notification using the
   'indp' Delivery Method.

   There is only one operation defined:  Send-Notifications.  Section
   6.2 assigns of the "operation-id" for the Send-Notifications
   operation and the following section defined the operation.


8.1 Send-Notifications operation

   This REQUIRED operation allows a Printer to send one or more Event
   Notifications to a Notification Recipient using HTTP.

   The Printer composes the information defined for an IPP Notification
   [ipp-ntfy] and sends it using the Send-Notifications operation to the
   Notification Recipient supplied in the Subscription object.  The
   ordering of separate Send-Notifications operations that a Printer
   sends MUST follow the "Event Notification Ordering" requirements in
   [ipp-ntfy] section 9.

   The Send-Notifications operation uses the operations model defined by
   IPP [RFC2566].  This includes, the use of a URI as the identifier for
   the target of each operation, the inclusion of a version number,
   operation-id, and request-id in each request, and the definition of
   attribute groups. The Send-Notifications operation uses the Operation
   Attributes group, but currently has no need for the Unsupported
   Attributes, Printer Object Attributes, and Job-Object Attributes
   groups. However, it uses a new attribute group, the Event
   Notification Attributes group.

   The Notification Recipient MUST accept the request in any state.
   There is no state defined for the Notification Recipient for this
   Delivery Method.

   Access Rights:  Notification Recipient MAY enforce access rights.  If
   the Printer receives a rejection with these status codes: 'client-
   error-forbidden', 'client-error-not-authenticated', or 'client-error-
   not-authorized' status code , the Printer SHOULD cancel the
   subscription.


8.1.1 Send-Notifications Request

   Every operation request MUST contains the following parameters (see
   [RFC2911] section 3.1.1):


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     - a "version-number"     '1.0' - the version of the 'indp'
       protocol is '1.0'.
     - an "operation-id" - the value defined in Table 2
     - a "request-id" - the request id (see [RFC2911] section 3.1.2).

   The following groups of attributes MUST be part of the Send-
   Notifications Request:


   Group 1: Operation Attributes
      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as defined in [RFC2911] section 3.1.4.1.

         The Printer MUST use the values of "notify-charset" and
         "notify-natural-language", respectively, from one Subscription
         Object associated with the Event Notifications in this request.

         Normally, there is only one matched Subscription Object, or the
         value of the "notify-charset" and "notify-natural-language"
         attributes is the same in all Subscription Objects. If not, the
         Printer MUST pick one Subscription Object from which to obtain
         the value of these attributes. The algorithm for picking the
         Subscription Object is implementation dependent. The choice of
         natural language is not critical because 'text' and 'name'
         values can override the "attributes-natural-language" Operation
         attribute. The Printer's choice of charset is critical because
         a bad choice may leave it unable to send some 'text' and 'name'
         values accurately.

      Target:
         A copy of the Subscription object's "notify-recipient-uri"
         (uri) attribute which is the target of this operation as
         described in [RFC2911] section 3.1.5, i.e., the URI of the
         'indp' Notification Recipient (see section 5.2.1).

   Group 2 to N: Event Notification Attributes

         In each group 2 to N, each attribute is encoded using the IPP
         rules for encoding attributes [RFC2910] and the attributes
         within a group MAY be encoded in any order.  Note: the Get-Jobs
         response in [RFC2911] acts as a model for encoding multiple
         groups of attributes.  The entire request is considered a
         single Compound Event Notification and MUST follow the "Event
         Notification Ordering" requirements for Event Notifications
         within a Compound Event Notification specified in [ipp-ntfy]
         section 9.


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         Each Event Notification Group MUST contain all of attributes
         specified in [ipp-ntfy] section 9.1 ("Content of Machine
         Consumable Event Notifications") with exceptions denoted by
         asterisks in the tables below.

         The tables below are copies of the tables in [ipp-ntfy] section
         9.1 ("Content of Machine Consumable Event Notifications")
         except that each cell in the "Sends" column is a  "MUST".

         For an Event Notification for all Events, the Printer sends the
         following attributes.






































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             Table 3 - Attributes in Event Notification Content


     Source Value                               Sends     Source Object


     notify-subscription-id (integer(1:MAX))    MUST      Subscription

     notify-printer-uri (uri)                   MUST      Subscription

     notify-subscribed-event (type2 keyword)    MUST      Event
                                                          Notification

     printer-up-time (integer(MIN:MAX))         MUST      Printer

     printer-current-time (dateTime)            MUST *    Printer

     notify-sequence-number (integer (0:MAX))   MUST      Subscription

     notify-charset (charset)                   MUST      Subscription

     notify-natural-language (naturalLanguage)  MUST      Subscription

     notify-user-data (octetString(63))         MUST **   Subscription

     notify-text (text (MAX))                   MUST      Event
                                                          Notification

     attributes from the "notify-attributes"    MUST ***  Printer
     attribute, if any

     attributes from the "notify-attributes"    MUST ***  Job
     attribute, if any

     attributes from the "notify-attributes"    MUST ***  Subscription
     attribute, if any


         * The Printer MUST send "printer-current-time" if and only if
         it supports the "printer-current-time" attribute on the Printer
         object.

         ** If the associated Subscription Object does not contain a
         "notify-user-data" attribute, the Printer MUST send an octet-
         string of length 0.

         *** If the "notify-attributes" attribute is present on the
         Subscription Object, the Printer MUST send all attributes

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         specified by the "notify-attributes" attribute. Note: if the
         Printer doesn't support the "notify-attributes" attribute, it
         is not present on the associated Subscription Object and the
         Printer does not send any client-requested attributes.

         For Event Notifications for Job Events, the Printer sends the
         following additional attributes shown in Table 4.

      Table 4 - Additional Attributes in Event Notification Content for
                                 Job Events


     Source Value                                   Sends     Source
                                                              Object


     job-id (integer(1:MAX))                        MUST      Job

     job-state (type1 enum)                         MUST      Job

     job-state-reasons (1setOf type2 keyword)       MUST      Job

     job-impressions-completed (integer(0:MAX))     MUST *    Job


         *  The Printer MUST send the "job-impressions-completed"
         attribute in an Event Notification only for the combinations of
         Events and Subscribed Events shown in Table 5.



      Table 5 - Combinations of Events and Subscribed Events for "job-
                           impressions-completed"


     Job Event                  Subscribed Job Event


     'job-progress'             'job-progress'

     'job-completed'            'job-completed'

     'job-completed'            'job-state-changed'


         For Event Notification for Printer Events, the Printer sends
         the following additional attributes shown in Table 6.


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      Table 6 - Additional Attributes in Event Notification Content for
                               Printer Events


     Source Value                                  Sends  Source Object


     printer-state (type1 enum)                    MUST   Printer

     printer-state-reasons (1setOf type2 keyword)  MUST   Printer

     printer-is-accepting-jobs (boolean)           MUST   Printer



8.1.2 Send-Notifications Response

   The Notification Recipient MUST return (to the client which is the
   Printer) the following sets of attributes as part of a Send-
   Notifications response:

   Every operation response contains the following REQUIRED parameters
   (see [RFC2911] section 3.1.1}:

     - a "version-number"
     - a "status-code"
     - the "request-id" that was supplied in the corresponding request

   Group 1: Operation Attributes

      Status Message:
         As defined in [RFC2911].

         The Notification Recipient can return any status codes defined
         in [RFC2911] and section 9.1 that applies to all of the Event
         Notification Attribute groups. The following is a description
         of the important status codes:

            'successful-ok': the Notification Recipient received all of
               the Event Notification Attribute Groups and was expecting
               each of them.

            'successful-ok-ignored-notifications': the Notification
               Recipient was able to consume some, but not all of the
               Event Notification Attributes Groups sent. The Event
               Notification Attributes Groups with a "notify-status-
               code" attribute are the ones that were ignored or are to
               be canceled.

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            'client-error-ignored-all-notifications': the Notification
               Recipient was unable to consume any of the Event
               Notification Attributes Groups sent. The Event
               Notification Attributes Groups with a "notify-status-
               code" attribute are the ones that were ignored or are to
               be canceled.

      Natural Language and Character Set:
         The "attributes-charset" and "attributes-natural-language"
         attributes as defined in [RFC2911] section 3.1.4.1.

   Group 2 to N: Notification Attributes

   These groups MUST be returned if and only if the "status-code"
   parameter returned in Group 1 is anything but the 'successful-ok'
   status code.

      "notify-status-code" (type2 enum)
         Indicates whether the Notification Recipient was able to
         consume the n-th Notification Report as follows:

            'successful-ok' - this Event Notification Attribute Group
               was consumed
            'client-error-not-found' - this Event Notification
               Attribute Group was not able to be consumed.  The Printer
               MUST cancel the Subscription and MUST NOT attempt to send
               any further Event Notifications from the associated
               Subscription object.
            'successful-ok-but-cancel-subscription' - the Event
               Notification Attribute Group was consumed, but the
               Notification Recipient wishes to cancel the Subscription
               object.  The Printer MUST cancel the Subscription and
               MUST NOT attempt to send any further Event Notifications
               from the associated Subscription object.

9 Status Codes

   This section lists status codes whose meaning have been extended
   and/or defined for returning in Event Notification Attribute Groups
   as the value of the "notify-status-code" operation attribute.  The
   code values are allocated in the same space as the status codes in
   [RFC2911].


9.1 Additional Status Codes

   The following status codes are defined as extensions for Notification
   and are returned as the value of the "status-code" parameter in the

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   Operation Attributes Group of a response (see [RFC2911] section
   3.1.6.1). Operations in this document can also return the status
   codes defined in section 13 of [RFC2911]. The 'successful-ok' status
   code is an example of such a status code.


9.1.1 successful-ok-ignored-notifications (0x0004)

   The Notification Recipient was able to consume some, but not all, of
   the Event Notifications Attributes Groups sent by the Printer in the
   Send-Notifications request.  See section 8.1.2 for further details.


9.1.2 client-error-ignored-all-notifications (0x0416)

   The Notification Recipient was unable to consume any of the Event
   Notification Attributes Groups sent by the Printer. The Event
   Notification Attributes Groups with a "notify-status-code" attribute
   are the ones that were ignored or are to be canceled.  The Printer
   MAY remove subscriptions for future events which this client was
   unable to consume.


9.2 Status Codes returned in Event Notification Attributes Groups

   This section contains values of the "notify-status-code" attribute
   that the Notification Recipient returns in a Event Notification
   Attributes Group in a response when the corresponding Event
   Notification Attributes Group in the request:

     1.was not consumed OR

     2.was consumed, but the Notification Recipient wants to cancel the
       corresponding Subscription object

   The following sections are ordered in decreasing order of importance
   of the status-codes.


9.2.1 client-error-not-found (0x0406)

   This status code is defined in [RFC2911]. This document extends its
   meaning and allows it to be returned in an Event Notification
   Attributes Group of a response.

   The Notification Recipient was unable to consume this Event
   Notification Attributes Group because it was not expected.  See
   section 8.1.2 for further details.

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9.2.2 successful-ok-but-cancel-subscription (0x0006)

   The Notification Recipient was able to consume this Event
   Notification Attributes Group that the Printer sent, but wants the
   corresponding Subscription object to be canceled none-the-less.  See
   section 8.1.2 for further details.


10 Encoding and Transport

   This section defines the encoding and transport used by the 'indp'
   Delivery Method.


10.1 Encoding of the Operation Layer

   The 'indp' Delivery Method uses the IPP operation layer encoding
   described in [RFC2910] and the Event Notification Attributes Group
   tag allocated by [ipp-ntfy] as shown in Table 7:

          Table 7 - The "event-notification-attributes-tag" value


   Tag Value (Hex)    Meaning


   0x07               "event-notification-attributes-tag"



10.2 Encoding of Transport Layer

   The 'indp' Notification Delivery Method uses the IPP transport layer
   encoding described in [RFC2910].

   It is REQUIRED that an 'indp' Notification Recipient implementation
   support HTTP over the IANA-assigned well known system port assigned
   to the 'indp' Delivery Method as its default port by IANA (see
   section 13), though a Notification Recipient implementation MAY
   support HTTP over some other port as well.


11 Conformance Requirements

   This section defines conformance requirements for Printers and
   Notification Recipients.



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11.1 Conformance Requirements for Printers

   The 'indp' Delivery Method is RECOMMENDED for a Printer to support.

   IPP Printers that conform to this specification:

   1.MUST meet the conformance requirements defined in [ipp-ntfy].

   2.MUST support the conformance requirements for Subscription object
     attributes defined in section 5, including the syntax for the
     "notify-recipient-uri" Subscription Object attribute defined in
     section 5.2.1.

   3.MUST support the conformance requirements for Printer Description
     object attributes defined in section 6.

   4.MUST support the 'indp' protocol by sending Event Notifications
     using the Send-Notifications operation defined in section 8.1.

   5.MUST send INDP URLs (e.g., in the "notify-recipient-uri" attribute
     in 'Send-Notifications') that conform to the ABNF specified in
     section 12.5 of this document;

   6.MUST send the Send-Notifications operation via the port specified
     in the INDP URL (if present) or otherwise via the IANA-assigned
     well-known system port xxx [TBA by IANA];

   7.MUST convert INDP URLs for use in the Send-Notifications operation
     to their corresponding HTTP URL forms for use in the HTTP layer by
     the same rules used to convert IPP URLs to their corresponding
     HTTP URL forms (see section 5 'IPP URL Scheme' in [RFC2910]).


11.2 Conformance Requirements for INDP Notification Recipients

   INDP Notification Recipients that conform to this specification:

   1.MUST accept Send-Notifications requests and return Send-
     Notifications responses as defined in sections 8 and 9.

   2.SHOULD reject received INDP URLs in "application/ipp" request
     bodies (e.g., in the "notify-recipient-uri" attribute in 'Send-
     Notifications') that do not conform to the ABNF for INDP URLs
     specified in section 12.5 of this document;

   3.MUST listen for INDP operations on IANA-assigned well-known system
     port xxx [TBA by IANA], unless explicitly configured by system
     administrators or site policies;

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   4.SHOULD NOT listen for INDP operations on any other port, unless
     explicitly configured by system administrators or site policies.


12 INDP URL Scheme


12.1 INDP URL Scheme Applicability and Intended Usage

   This section is intended for use in registering the "indp" URL scheme
   with IANA and fully conforms to the requirements in [RFC2717].  This
   document defines the "indp" URL (Uniform Resource Locator) scheme for
   specifying the location of an INDP Notification Recipient object
   which implements IPP Notification Delivery Protocol (INDP) specified
   in this document.

   The intended usage of the "indp" URL scheme is COMMON.


12.2 INDP URL Scheme Associated INDP Port

   All INDP URLs which do NOT explicitly specify a port MUST be used
   over IANA-assigned well-known system port xxx [TBA by IANA] for the
   INDP protocol.

   See:  IANA Port Numbers Registry [IANA-PORTREG].


12.3 INDP URL Scheme Associated MIME Type

   All INDP protocol operations (requests and responses) MUST be
   conveyed in an "application/ipp" MIME media type as registered in
   [IANA-MIMEREG].  INDP URLs MUST refer to INDP Notification Recipient
   objects which support this "application/ipp" MIME media type.

   See:  IANA MIME Media Types Registry [IANA-MIMEREG].


12.4 INDP URL Scheme Character Encoding

   The INDP URL scheme defined in this document is based on the ABNF for
   the HTTP URL scheme defined in HTTP/1.1 [RFC2616], which is derived
   from the URI Generic Syntax [RFC2396] and further updated by
   [RFC2732] and [RFC2373] (for IPv6 addresses in URLs).  The INDP URL
   scheme is case-insensitive in the 'scheme' and 'host' (host name or
   host address) part; however the 'abs_path' part is case-sensitive, as
   in [RFC2396].  Code points outside [US-ASCII] MUST be hex escaped by
   the mechanism specified in [RFC2396].

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12.5 INDP URL Scheme Syntax in ABNF

   The IPP protocol places a limit of 1023 octets (NOT characters) on
   the length of a URI (see section 4.1.5 'uri' in [RFC2911]).  An INDP
   Notification Recipient MUST return 'client-error-request-value-too-
   long' (see section 13.1.4.10 in [RFC2911]) when a URI received in a
   request is too long.

   Note:  INDP Notification Recipients ought to be cautious about
   depending on URI lengths above 255 bytes, because some older client
   or proxy implementations might not properly support these lengths.

   INDP URLs MUST be represented in absolute form.  Absolute URLs always
   begin with a scheme name followed by a colon.  For definitive
   information on URL syntax and semantics, see "Uniform Resource
   Identifiers (URI): Generic Syntax and Semantics" [RFC2396].  This
   specification adopts the definitions of "port", "host", "abs_path",
   and "query" from [RFC2396], as updated by [RFC2732] and [RFC2373]
   (for IPv6 addresses in URLs).

   The INDP URL scheme syntax in ABNF is as follows:

     indp_URL = "indp:" "//" host [ ":" port ] [ abs_path [ "?" query ]]

   If the port is empty or not given, IANA-assigned well-known system
   port xxx [TBA by IANA] is assumed.  The semantics are that the
   identified resource (see section 5.1.2 of [RFC2616]) is located at
   the INDP Notification Recipient listening for HTTP connections on
   that port of that host, and the Request-URI for the identified
   resource is 'abs_path'.

   Note:  The use of IP addresses in URLs SHOULD be avoided whenever
   possible (see [RFC1900]).

   If the 'abs_path' is not present in the URL, it MUST be given as "/"
   when used as a Request-URI for a resource (see section 5.1.2 of
   [RFC2616]).  If a proxy receives a host name which is not a fully
   qualified domain name, it MAY add its domain to the host name it
   received.  If a proxy receives a fully qualified domain name, the
   proxy MUST NOT change the host name.


12.5.1 INDP URL Examples

   The following are examples of valid INDP URLs for Notification
   Recipient objects (using DNS host names):

     indp://abc.com

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     indp://abc.com/listener

   Note:  The use of IP addresses in URLs SHOULD be avoided whenever
   possible (see [RFC1900]).

   The following literal IPv4 addresses:

     192.9.5.5                    ; IPv4 address in IPv4 style
     186.7.8.9                    ; IPv4 address in IPv4 style

   are represented in the following example INDP URLs:

     indp://192.9.5.5/listener
     indp://186.7.8.9/listeners/tom

   The following literal IPv6 addresses (conformant to [RFC2373]):

     ::192.9.5.5                  ; IPv4 address in IPv6 style
     ::FFFF:129.144.52.38         ; IPv4 address in IPv6 style
     2010:836B:4179::836B:4179    ; IPv6 address per RFC 2373

   are represented in the following example INDP URLs:

     indp://[::192.9.5.5]/listener
     indp://[::FFFF:129.144.52.38]/listener
     indp://[2010:836B:4179::836B:4179]/listeners/tom


12.5.2 INDP URL Comparisons

   When comparing two INDP URLs to decide if they match or not, the
   comparer MUST use the same rules as those defined for HTTP URI
   comparisons in [RFC2616], with the sole following exception:

     ? A port that is empty or not given MUST be treated as equivalent
       to the well-known system port xxx [TBA by IANA] for that INDP
       URL;



13 IANA Considerations

   IANA shall register the indp URL scheme as defined in section 12
   according to the procedures of [RFC2717] and assign a well-known
   system port.




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   The rest of this section contains the exact information for IANA to
   add to the IPP Registries according to the procedures defined in RFC
   2911 [RFC2911] section 6.

     Note to RFC Editors:  Replace RFC NNNN below with the RFC number
     for this document, so that it accurately reflects the content of
     the information for the IANA Registry.


13.1 Operation Registrations

   The following table lists the operation defined in this document.
   This is to be registered according to the procedures in RFC 2911
   [RFC2911] section 6.4.

       Operations:                                       Ref.
   Section:
   Send-Notifications operation                      RFC NNNN   8.1

   The resulting operation registration will be published in the
   ftp://ftp.iana.org/in-notes/iana/assignments/ipp/operations/
   area.


13.2 Additional attribute value registrations for existing attributes

   This section lists additional attribute value registrations for use
   with existing attributes defined in other documents.


13.2.1 Additional values for the "notify-schemes-supported" Printer
     attribute

   The following table lists the uriScheme value defined in this
   document as an additional uriScheme value for use with the "notify-
   schemes-supported" Printer attribute defined in [ipp-ntfy].  This is
   to be registered according to the procedures in RFC 2911 [RFC2911]
   section 6.1.

   uriScheme Attribute Values:                     Ref.     Section:
   indp                                            RFC NNNN    6.1


   The resulting URI scheme attribute value registration will be
   published in the
   ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-

   values/notify-schemes-supported/

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   area.



13.2.2 Additional values for the "operations-supported" Printer
     attribute

   The following table lists the enum attribute value defined in this
   document as an additional type2 enum value for use with the
   "operations-supported" Printer attribute defined in [RFC2911]. This
   is to be registered according to the procedures in RFC 2911 [RFC2911]
   section 6.1.

   type2 enum Attribute Values:         Value      Ref.     Section:
   Send-Notifications                   0x001D     RFC NNNN    6.2


   The resulting enum attribute value registration will be published in
   the
   ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-
   values/operations-supported/
   area.



13.3 Status code Registrations

   The following table lists all the status codes defined in this
   document.  These are to be registered according to the procedures in
   RFC 2911 [RFC2911] section 6.6.

   Status codes:                                   Ref.     Section:
   successful-ok-ignored-notifications (0x0004)    RFC NNNN    9.1.1
   client-error-ignored-all-notifications (0x0416) RFC NNNN    9.1.2

   Status Codes in Event Notification Attributes Groups:
   client-error-not-found (0x0406)                 RFC NNNN    9.2.1
   successful-ok-but-cancel-subscription (0x0006)  RFC NNNN    9.2.2

   The resulting status code registrations will be published in the
   ftp://ftp.iana.org/in-notes/iana/assignments/ipp/status-codes/
   area.


14 Internationalization Considerations

   When the client requests Human Consumable form by supplying the
   "notify-text-format" operation attribute (see [ipp-ntfy]), the IPP

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   Printer (or any Notification Service that the IPP Printer might be
   configured to use) supplies and localizes the text value of the
   "human-readable-report" attribute in the Notification according to
   the charset and natural language requested in the notification
   subscription.


15 Security Considerations

   The IPP Model and Semantics document [RFC2911] discusses high level
   security requirements (Client Authentication, Server Authentication
   and Operation Privacy). Client Authentication is the mechanism by
   which the client proves its identity to the server in a secure
   manner. Server Authentication is the mechanism by which the server
   proves its identity to the client in a secure manner. Operation
   Privacy is defined as a mechanism for protecting operations from
   eavesdropping.

   The Notification Recipient can cancel unwanted Subscriptions created
   by other parties without having to be the owner of the subscription
   by returning the 'successful-ok-but-cancel-subscription' status code
   in the Send-Notifications response returned to the Printer.

15.1 Security Conformance

   Printers (client) MAY support Digest Authentication [RFC2617].  If
   Digest Authentication is supported, then MD5 and MD5-sess MUST be
   supported, but the Message Integrity feature NEED NOT be supported.

   Notification Recipient (server) MAY support Digest Authentication
   [RFC2617].  If Digest Authentication is supported, then MD5 and MD5-
   sess MUST be supported, but the Message Integrity feature NEED NOT be
   supported.

   Notification Recipients MAY support TLS for client authentication,
   server authentication and operation privacy. If a Notification
   Recipient supports TLS, it MUST support the
   TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA cipher suite as mandated by RFC
   2246 [RFC2246]. All other cipher suites are OPTIONAL. Notification
   recipients MAY support Basic Authentication (described in HTTP/1.1
   [RFC2616]) for client authentication if the channel is secure. TLS
   with the above mandated cipher suite can provide such a secure
   channel.






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16 References


   [ipp-iig]
     Hastings, T., Manros, C., Kugler, K, Holst H., Zehler, P.,
     "Internet Printing Protocol/1.1:  draft-ietf-ipp-implementers-
     guide-v11-03.txt, work in progress, July 17, 2001

   [ipp-ntfy]
     Isaacson, S., Martin, J., deBry, R., Hastings, T., Shepherd, M.,
     Bergman, R., "Internet Printing Protocol/1.1: IPP Event
     Notifications and Subscriptions", <draft-ietf-ipp-not-spec-07.txt>,
     July 17, 2001.

   [IANA-MIMEREG]
     IANA MIME Media Types Registry.  ftp://ftp.iana.org/in-

     notes/iana/assignments/media-types/


   [IANA-PORTREG]
     IANA Port Numbers Registry.  ftp://ftp.iana.org/in-

     notes/iana/assignments/port-numbers


   [RFC1900]
     B. Carpenter, Y. Rekhter.  Renumbering Needs Work, RFC 1900,
     February 1996.

   [RFC2026]
     S. Bradner, "The Internet Standards Process -- Revision 3", RFC
     2026, October 1996.

   [RFC2373]
     R. Hinden, S. Deering.  IP Version 6 Addressing Architecture, RFC
     2373, July 1998.

   [RFC2396]
     Berners-Lee, T. et al.  Uniform Resource Identifiers (URI): Generic
     Syntax, RFC 2396, August 1998

   [RFC2565]
     Herriot, R., Butler, S., Moore, P., and R. Turner, "Internet
     Printing Protocol/1.0: Encoding and Transport", RFC 2565, April
     1999.



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   [RFC2566]
     R. deBry, T. Hastings, R. Herriot, S. Isaacson, and P. Powell,
     "Internet Printing Protocol/1.0: Model and Semantics", RFC 2566,
     April 1999.

   [RFC2567]
     Wright, D., "Design Goals for an Internet Printing Protocol", RFC
     2567, April 1999.

   [RFC2568]
     Zilles, S., "Rationale for the Structure and Model and Protocol for
     the Internet Printing Protocol", RFC 2568, April 1999.

   [RFC2569]
     Herriot, R., Hastings, T., Jacobs, N., Martin, J., "Mapping between
     LPD and IPP Protocols", RFC 2569, April 1999.

   [RFC2616]
     R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P.
     Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
     RFC 2616, June 1999.

   [RFC2617]
     J. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence, P. Leach, A.
     Luotonen, L. Stewart, "HTTP Authentication: Basic and Digest Access
     Authentication", RFC 2617, June 1999.

   [RFC2717]
     R. Petke and I. King, "Registration Procedures for URL Scheme
     Names", RFC 2717, November 1999.

   [RFC2732]
     R. Hinden, B. Carpenter, L. Masinter.  Format for Literal IPv6
     Addresses in URL's, RFC 2732, December 1999.

   [RFC2910]
     Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing
     Protocol/1.1: Encoding and Transport", RFC 2910, September 2001.

   [RFC2911]
     R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
     "Internet Printing Protocol/1.1: Model and Semantics", RFC 2911,
     September 2001.


17 Author's Addresses

     Hugo Parra

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     Novell, Inc.
     1800 South Novell Place

      Provo, UT   84606

     Phone: 801-861-3307
     Fax:   801-861-2517
     e-mail: hparra@novell.com

     Tom Hastings
     Xerox Corporation
     737 Hawaii St.  ESAE 231
     El Segundo, CA   90245

     Phone: 310-333-6413
     Fax:   310-333-5514
     e-mail: hastings@cp10.es.xerox.com


   IPP Web Page:  http://www.pwg.org/ipp/
   IPP Mailing List:  ipp@pwg.org

   To subscribe to the ipp mailing list, send the following email:
     1) send it to majordomo@pwg.org
     2) leave the subject line blank
     3) put the following two lines in the message body:
          subscribe ipp
          end

   Implementers of this specification document are encouraged to join
   the IPP Mailing List in order to participate in any discussions of
   clarification issues and review of registration proposals for
   additional attributes and values.  In order to reduce spam the
   mailing list rejects mail from non-subscribers, so you must subscribe
   to the mailing list in order to send a question or comment to the
   mailing list.


18 Summary of Base IPP documents

   The base IPP documents includes:

      Design Goals for an Internet Printing Protocol [RFC2567]
      Rationale for the Structure and Model and Protocol for the
            Internet Printing Protocol [RFC2568]
      Internet Printing Protocol/1.1: Model and Semantics [RFC2911]
      Internet Printing Protocol/1.1: Encoding and Transport [RFC2910]
      Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig]

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      Mapping between LPD and IPP Protocols [RFC2569]
      Internet Printing Protocol (IPP):  IPP Event Notifications and
            Subscriptions [ipp-ntfy]

   The "Design Goals for an Internet Printing Protocol" document takes a
   broad look at distributed printing functionality, and it enumerates
   real-life scenarios that help to clarify the features that need to be
   included in a printing protocol for the Internet.  It identifies
   requirements for three types of users: end users, operators, and
   administrators.  It calls out a subset of end user requirements that
   are satisfied in IPP/1.0 [RFC2566, RFC2565].  A few OPTIONAL operator
   operations have been added to IPP/1.1 [RFC2911, RFC2910].

   The "Rationale for the Structure and Model and Protocol for the
   Internet Printing Protocol" document describes IPP from a high level
   view, defines a roadmap for the various documents that form the suite
   of IPP specification documents, and gives background and rationale
   for the IETF working group's major decisions.

   The "Internet Printing Protocol/1.1: Model and Semantics" document
   describes a simplified model with abstract objects, their attributes,
   and their operations that are independent of encoding and transport.
   It introduces a Printer and a Job object.  The Job object optionally
   supports multiple documents per Job.  It also addresses security,
   internationalization, and directory issues.

   The "Internet Printing Protocol/1.1: Encoding and Transport" document
   is a formal mapping of the abstract operations and attributes defined
   in the model document onto HTTP/1.1 [RFC2616].  It defines the
   encoding rules for a new Internet MIME media type called
   "application/ipp".  This document also defines the rules for
   transporting a message body over HTTP whose Content-Type is
   "application/ipp".  This document defines the 'ipp' scheme for
   identifying IPP printers and jobs.

   The "Internet Printing Protocol/1.1: Implementer's Guide" document
   gives insight and advice to implementers of IPP clients and IPP
   objects.  It is intended to help them understand IPP/1.1 and some of
   the considerations that may assist them in the design of their client
   and/or IPP object implementations.  For example, a typical order of
   processing requests is given, including error checking.  Motivation
   for some of the specification decisions is also included.

   The "Mapping between LPD and IPP Protocols" document gives some
   advice to implementers of gateways between IPP and LPD (Line Printer
   Daemon) implementations.



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   The "Internet Printing Protocol (IPP):  IPP Event Notifications and
   Subscriptions" document defines an extension to IPP/1.0 [RFC2566,
   RFC2565] and IPP/1.1  [RFC2911, RFC2910].  This extension allows a
   client to subscribe to printing related Events by creating a
   Subscription Object and defines the semantics for delivering
   asynchronous Event Notifications to the specified Notification
   Recipient via a specified Delivery Method (i.e., protocols) defined
   in (separate) Delivery Method documents.


19 Full Copyright Statement

   Copyright (C) The Internet Society (2001). 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
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Acknowledgement

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   Internet Society.







Parra, Hastings        Expires: January 17, 2002              [page 32]