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Versions: 00 01 02 03 04 05 06                                          
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<draft-ietf-ipp-indp-method-01.txt>
                                                              Hugo Parra
                                                            Novell, Inc.
                                                            Tom Hastings
                                                             Xerox Corp.
                                                            July 6, 2000

                   Internet Printing Protocol (IPP):

                The 'indp' Notification Delivery Method


    Copyright (C) The Internet Society (2000). 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

The IPP Event Notification specification [ipp-ntfy] is an OPTIONAL
extension to IPP/1.0, IPP/1.1, and future versions.  [ipp-ntfy] requires
the definition of one or more Delivery Methods in separate Delivery
Method Documents for the Printer to dispatch Event Notifications to
Notification Recipients. This Delivery Method Document defines the
semantics and syntax of the 'indp' Notification Delivery Method.  For
this Delivery Method, an IPP Printer sends (pushes) an IPP Event
Notifications request to the Notification Recipients using the Send-
Notifications operation defined in this document.  The Notification
Recipient returns a response to the Printer.  The Send-Notifications
operation uses the same Encoding and Transport as IPP itself.








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The full set of 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 [ipp-mod]
  Internet Printing Protocol/1.1: Encoding and Transport [ipp-pro]
  Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig]
  Mapping between LPD and IPP Protocols [RFC2569]
  Internet Printing Protocol (IPP):  IPP Event Notification
     Specification [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.  A few OPTIONAL operator operations have been
added to IPP/1.1.

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: 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 a
new scheme named 'ipp' 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.

The "Internet Printing Protocol (IPP):  IPP Event Notification
Specification" document defines the semantics for Subscription Creation
Operations and the requirements for other Delivery Method documents to
define a Delivery Method to carry an Event Notifications to a
Notification Recipient.



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                           Table of Contents


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

2  Terminology.......................................................5

3  Model and Operation...............................................5

4  Summary of the 'indp' Delivery Method.............................6

5  Subscription object attributes....................................8
 5.1SUBSCRIPTION TEMPLATE ATTRIBUTE CONFORMANCE......................8
 5.2SUBSCRIPTION DESCRIPTION ATTRIBUTE CONFORMANCE...................8

6  Printer Description Attribute Conformance.........................9

7  New Values for Existing Printer Description Attributes............9
 7.1NOTIFY-SCHEMES-SUPPORTED (1SETOF URISCHEME)......................9
 7.2OPERATIONS-SUPPORTED (1SETOF TYPE2 ENUM).........................9
 0X001D..............................................................9

8  Attributes Only in Event Notifications............................9

9  Operations for Notification.......................................9
 9.1SEND-NOTIFICATIONS OPERATION....................................10
   9.1.1 Send-Notifications Request.................................10
   9.1.2 Send-Notifications Response................................13
 9.2NOTIFICATION PROTOCOL URI SCHEME................................14

10 Status Codes.....................................................15
 10.1 ADDITIONAL STATUS CODES.......................................15
   10.1.1 successful-ok-ignored-notifications (0x0004)..............15
 10.2 STATUS CODES RETURNED IN EVENT NOTIFICATION ATTRIBUTES GROUPS.15
   10.2.1 client-error-not-found (0x0406)...........................15
   10.2.2 successful-ok-but-cancel-subscription (0x0006)............16

11 Encoding and Transport...........................................16
 11.1 ENCODING OF THE OPERATION LAYER...............................16
 11.2 ENCODING OF TRANSPORT LAYER...................................16

12 IANA Considerations..............................................16

13 Internationalization Considerations..............................16

14 Security Considerations..........................................17
 14.1 SECURITY CONFORMANCE..........................................17

15 References.......................................................17

16 Author's Addresses...............................................18


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17 Full Copyright Statement.........................................18



                                 Tables

Table 1 - Summary of the 'indp' Delivery Method.......................6

Table 2 . Operation-id assignments....................................9

Table 3 . Attributes in Event Notification Content...................11

Table 4 . Additional Attributes in Event Notification Content for Job
   Events............................................................12

Table 5 . Combinations of Events and Subscribed Events for .job-
   impressions-completed............................................13

Table 6 . Additional Attributes in Event Notification Content for
   Printer Events...................................................13



































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1  Introduction

The notification extension document [ipp-ntfy] 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. 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 notification extension 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.

For the .indp. Delivery Method, an IPP Printer sends (pushes) a Send-
Notifications operation request containing one or more Event
Notifications to a Notification Recipient.  The Notification Recipient
returns a response to the Printer.  The Send-Notifications operation
uses the same Encoding and Transport as IPP itself.


2  Terminology

This document uses terms such as "attributes", "keywords", and
"support".  These terms have special meaning and are defined in the
model terminology [ipp-mod] section 12.2.

Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT,
MAY, NEED NOT, and OPTIONAL, have special meaning relating to
conformance.  These terms are defined in [ipp-mod] section 12.1 on
conformance terminology, most of which is taken from RFC 2119 [RFC2119].

This document uses the capitalized terms, such as Notification
Recipient, Event Notification, Printer, etc.,  that are defined in [ipp-
ntfy] with the same meanings and are not reproduced here.

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

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

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.




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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 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 11.2 for more details.


4  Summary of the 'indp' Delivery Method

Column 1 of Table 1 lists the conformance requirements for Delivery
Method Documents as specified in [ipp-ntfy].  Column 2 indicates how
this Delivery Method Document meets each requirement:

            Table 1 - Summary of the 'indp' Delivery Method

Document Method conformance     'indp' realization
requirement

1.MUST define a URL scheme      indp
name for the Delivery Method.

2.MUST indicate whether the     OPTIONAL
delivery method is REQUIRED or
OPTIONAL for an IPP Printer to
support if it supports Event
Notification.

3.MUST define the transport     a complete HTTP stack [rfc2616]
and delivery protocol for the
Event Notification content that
a Printer MUST use, i.e., the
entire network stack.

4.MUST indicate whether or not  yes, see section 9.1.1
several Event Notifications can


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Document Method conformance     'indp' realization
requirement

be combined into a compound
Event Notification.

5.MUST describe how the         initiated by the Printer (push)
Delivery Method is initiated,
i.e., is it initiated by the
receiving user (pull), or is it
initiated by the Printer
(push).

6.MUST indicate whether the     Machine Consumable with the
Delivery Method is Machine      "notify-text" attribute being
Consumable or Human Consumable. Human Consumable

7.MUST define the               The representation and encoding
representation and encoding     is the same as IPP.  See
that a Printer MUST use for     section 9.1.1
each value or piece of
information listed in [ipp-
ntfy] section 9 (9.1 for
Machine Consumable Event
Notification and/or section 9.2
for Human Consumable Event
Notification).

8.MUST specify for each         See the Send-Notifications
attribute in [ipp-ntfy] section Request defined in section
9 whether a Printer MUST,       9.1.1
SHOULD, MAY, MUST NOT, SHOULD
NOT or NEED NOT send the
attribute in an Event
Notification content.

9.MUST define what frequently   Frequently occurring Events
occurring Events MUST be        NEED NOT be moderated because
moderated, if any, and whether  the Delivery Method is an
the moderation mechanism is     efficient one and because the
configurable. Also whether      Printer can group multiple
Events are moderated by sending Event Notifications for the
one per time unit or one per    same Notification Recipient
number of Events.               into a single Send-
                                Notifications operations.

10.  MUST discuss the latency   Same as for IPP/1.0 or IPP/1.1
and reliability of the          itself (see [ipp-mod]).
transport and delivery
protocol.

11.  MUST discuss the security  See section 14
aspects of the transport and

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Document Method conformance     'indp' realization
requirement

delivery protocol, e.g., how it
is handled in firewalls.

12.  MUST identify content      They are the same as for
length restrictions, if any.    IPP/1.0 and IPP/1.1 itself (see
                                [ipp-mod]).

13.  MAY define additional      A new Event Notifications
values or pieces of information attribute group (see section
that a Printer MUST, SHOULD or  11.1) and additional status
MAY send in a Notification      codes for use in the response
content.                        (see section 10)

14.  MAY define additional      none defined
Subscription Template and/or
Subscription Description
attributes and the conformance
requirements thereof.

15.  MAY define additional      none defined
Printer Description attributes
and the conformance
requirements thereof.

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


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 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  Printer Description Attribute Conformance

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


7  New Values for Existing Printer Description Attributes

This section defines additional values for existing Printer Description
attributes.


7.1 notify-schemes-supported (1setOf uriScheme)


The following .notify-schemes-supported. value is added in order to
support the new Delivery Method defined in this document:

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

7.2 operations-supported (1setOf type2 enum)


Table 2 lists the .operation-id. value 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




8  Attributes Only in Event Notifications

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


9  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 7.2
assigns of the .operation-id. for the Send-Notifications operation and
the following section defined the operation.




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9.1 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 Sent-Notifications operation to the
Notification Recipient supplied in the Subscription object.

The Send-Notifications operations 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:  To send Event Notifications to a Notification Recipient,
the authenticated user (see [IPP-MOD] section 8.3) performing this
operation MUST be the Printer that accepted a previous Subscription
Creation operation (see [ipp-ntfy]).  Otherwise the Notification
Recipient MUST reject the operation and return: the .client-error-
forbidden., .client-error-not-authenticated., or .client-error-not-
authorized. status code as appropriate.

ISSUE 01:  Is this what the Access Rights section should say for a Send-
Notifications request?


9.1.1 Send-Notifications Request

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

     - a "version-number"    ISSUE 02:  What version number goes here?
     - an "operation-id" - the value defined in Table 2
     - a "request-id" - the contents of the Subscription object's
       "notify-sequence-number" after incrementing for the first try
       (see [ipp-ntfy]).

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

Group 1: Operation Attributes
     Natural Language and Character Set:



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          The "attributes-charset" and "attributes-natural-language"
          attributes as defined in [ipp-mod] section 3.1.4.1.

     Target:
          A copy of the Subscription object's "notification-recipient-
          uri" (uri) attribute which is the target of this operation as
          described in [ipp-mod] section 3.1.5, i.e., the URI of the
          'indp' Notification Recipient (see section 9.2).

  Requesting User Name:
     Unlike the other IPP operations, the .requesting-user-name.
     attribute SHOULD NOT be supplied by the client as described in
     [ipp-mod] section 8.3.
          ISSUE 03:  Ok that "requesting-user-name" SHOULD NOT be send
          in Send-Notifications?

Group 2 to N: Event Notification Attributes

     In each group 2 to N, each attribute is encoded using the IPP rules
     for encoding attributes [ipp-pro] and may be encoded in any order.
     Note: the Get-Jobs response in [ipp-mod] acts as a model for
     encoding multiple groups of attributes.

     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.

             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



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                    Source Value                 Sends   Source Object

     notify-natural-language (naturalLanguage)   MUST   Subscription

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

     notify-text (text)                          MUST   Event
                                                          Notification

     attributes from the .notify-attributes.     MUST   Printer
     attribute ***

     attributes from the .notify-attributes.     MUST   Job
     attribute ***

     attributes from the .notify-attributes.     MUST   Subscription
     attribute ***


     ISSUE 04: Ok that "notify-text" has been changed from MAY to MUST?

     * 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 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.

     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                   MUST   Job
     (integer(0:MAX)) *




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     *  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.

      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         MUST   Printer
     keyword)

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





9.1.2 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
[ipp-mod] 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 [ipp-mod].




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     The Notification Recipient can return any status codes defined in
     [ipp-mod] and section 10.1 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.
       '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 [ipp-mod] 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.

  "notification-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.

9.2  Notification Protocol URI Scheme


The INDP Notification Delivery Method uses the 'indp://' URI scheme in
the "notify-recipients" attribute in the Subscription object in order to
indicate the notification Delivery Method defined in this document.  The
remainder of the URI indicates the host and address of the Notification
Recipient that is to receive the Send-Notification operation.


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10 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 "notification-status-code" operation attribute.  The code
values are allocated in the same space as the status codes in [ipp-mod].


10.1 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
Operation Attributes Group of a response (see [ipp-mod] section
3.1.6.1). Operations in this document can also return the status codes
defined in section 13 of [ipp-mod]. The .successful-ok. status code is
an example of such a status code.


10.1.1    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 9.1.2 for further details.


10.2 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.


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

This status code is defined in [ipp-mod]. 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 9.1.2 for
further details.






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10.2.2    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 9.1.2 for
further details.


11 Encoding and Transport

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


11.1 Encoding of the Operation Layer


The 'indp' Delivery Method uses the IPP operation layer encoding
described in [ipp-pro] and the following Event Notification Attributes
Group tag allocated by [ipp-ntfy]:

   Tag Value (Hex)   Meaning

   0x07              .event-notification-attributes-tag.



11.2 Encoding of Transport Layer


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

It is REQUIRED that an 'indp' Notification Recipient implementation
support HTTP over the IANA assigned Well Known Port assigned to the
'indp' Delivery Method as its default port by IANA (see section 12),
though a Notification Recipient implementation MAY support HTTP over
some other port as well.


12 IANA Considerations

The 'indp://' URL scheme for the 'indp' Delivery Method will be
registered with IANA.  IANA will assign a default port to use with the
'indp' Delivery Method.


13 Internationalization Considerations

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




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14 Security Considerations

The IPP Model and Semantics document [ipp-mod] 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.

14.1 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.


15 References


[indp]
     Parra, H., T. Hastings,  "Internet Printing Protocol (IPP): IPP
     Notification Delivery Protocol (INDP)", <draft-ietf-indp-00.txt>,
     February 29, 2000.

[ipp-mod]
     R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
     "Internet Printing Protocol/1.0: Model and Semantics", <draft-ietf-
     ipp-model-v11-07.txt>, May 22, 2000.

[ipp-ntfy]
     Isaacson, S., Martin, J., deBry, R., Hastings, T., Shepherd, M.,
     Bergman, R., "Internet Printing Protocol/1.1: IPP Event
     Notification Specification", <draft-ietf-ipp-not-spec-03.txt>, June
     30, 2000.


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[ipp-pro]
     Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing
     Protocol/1.1: Encoding and Transport", draft-ietf-ipp-protocol-v11-
     06.txt, May 30, 2000.

[rfc2026]
     S. Bradner, "The Internet Standards Process -- Revision 3", RFC
     2026, October 1996.

[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.


16 Author's Addresses

     Hugo Parra
     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


17 Full Copyright Statement

Copyright (C) The Internet Society (2000). 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

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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 assigns.

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









































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