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INTERNET-DRAFT
<draft-ietf-ipp-indp-method-03.txt>
Category:  standards track                                    Hugo Parra
                                                            Novell, Inc.
                                                            Tom Hastings
                                                             Xerox Corp.
                                                         August 29, 2000
                   Internet Printing Protocol (IPP):
  The 'indp' Delivery Method for Event Notifications and Protocol/1.0

    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 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. 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).


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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 and Protocol.
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 this Delivery Method, when an Event occurs, the Printer immediately
sends (pushes) an Event Notification via the Send-Notifications
operation 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 returns a response to the Printer.




































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The basic 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: 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 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


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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 ......................................................7

2  Terminology .......................................................7

3  Model and Operation ...............................................8

4  General Information ...............................................9

5  Subscription object attributes ...................................12
 5.1 SUBSCRIPTION TEMPLATE ATTRIBUTE CONFORMANCE.....................12
 5.2 ADDITIONAL INFORMATION ABOUT SUBSCRIPTION TEMPLATE ATTRIBUTES...13
   5.2.1 ....................................notify-recipient-uri (uri)
        13
 5.3 SUBSCRIPTION DESCRIPTION ATTRIBUTE CONFORMANCE..................13

6  Printer Description Attributes ...................................13
 6.1 PRINTER DESCRIPTION ATTRIBUTE CONFORMANCE.......................13
 6.2 NEW VALUES FOR EXISTING PRINTER DESCRIPTION ATTRIBUTES..........14
   6.2.1 ...................notify-schemes-supported (1setOf uriScheme)
        14
   6.2.2 ......................operations-supported (1setOf type2 enum)
        14

7  Attributes Only in Event Notifications ...........................14

8  Operations for Notification ......................................15
 8.1 SEND-NOTIFICATIONS OPERATION....................................15
   8.1.1 ....................................Send-Notifications Request
        16
   8.1.2 ...................................Send-Notifications Response
        20

9  Status Codes .....................................................22
 9.1 ADDITIONAL STATUS CODES.........................................22
   9.1.1 ..................successful-ok-ignored-notifications (0x0004)
        22
 9.2 STATUS CODES RETURNED IN EVENT NOTIFICATION ATTRIBUTES GROUPS...22
   9.2.1 ...............................client-error-not-found (0x0406)
        23
   9.2.2 ................successful-ok-but-cancel-subscription (0x0006)
        23

10 Encoding and Transport ...........................................23


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 10.1 ENCODING OF THE OPERATION LAYER ...............................23
 10.2 ENCODING OF TRANSPORT LAYER ...................................24

11 Conformance Requirements .........................................24
 11.1 PRINTER CONFORMANCE REQUIREMENTS ..............................24
 11.2 NOTIFICATION RECIPIENT REQUIREMENTS ...........................25

12 IANA Considerations ..............................................25

13 Internationalization Considerations ..............................25

14 Security Considerations ..........................................25
 14.1 SECURITY CONFORMANCE ..........................................25

15 References .......................................................26

16 Author's Addresses ...............................................27

17 Full Copyright Statement .........................................27




                                 Tables


Table 1 - Information about the Delivery Method.......................9


Table 2 - Operation-id assignments...................................14


Table 3 - Attributes in Event Notification Content...................17


Table 4 - Additional Attributes in Event Notification Content for Job
   Events ...........................................................19


Table 5 - Combinations of Events and Subscribed Events for "job-
   impressions-completed" ...........................................19


Table 6 - Additional Attributes in Event Notification Content for
   Printer Events ...................................................20






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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.  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.


2  Terminology

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


  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 as specified in RFC 2119 [RFC2119] and [ipp-mod]


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     section 12.1.  These terms refer to conformance to this document,
     if this document is implemented.


  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.


  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.


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 10.2 for more details.



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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 Printer supports this Delivery Method, Table 1 lists its
characteristics.


            Table 1 - Information about the Delivery Method



Document Method conformance     'indp' realization
requirement




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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  RECOMMENDED
support?



3.What transport and delivery   A Printer MUST support a
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?



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



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Document Method conformance     'indp' realization
requirement



7.What section in this          The representation and encoding
document 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 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      Same as for IPP/1.0 or IPP/1.1
reliability of the transport    itself (see [ipp-mod]).
and delivery protocol?



9.What are the security         See section 14
aspects of the transport and
delivery protocol, e.g., how it
is handled in firewalls?



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



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



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Document Method conformance     'indp' realization
requirement


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
Printer Description attributes
and the conformance             None
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.








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5.2 Additional Information about Subscription Template Attributes


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


5.2.1notify-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 and address of the Notification Recipient that is to receive
    the Send-Notification operation.


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.


6  Printer Description Attributes

This section defines the Printer Description Attributes conformance
requirements for Printers.


6.1 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.





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6.2 New Values for Existing Printer Description Attributes


This section defines additional values for existing Printer Description
attributes.


6.2.1notify-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.

6.2.2operations-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






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 6.2.2
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 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:  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.





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8.1.1Send-Notifications Request


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

     - 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 [ipp-mod] 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 [ipp-mod] 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 "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 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 [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.



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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.

             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 (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 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.


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     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)) *



     *  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'






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     '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






8.1.2Send-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}:



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     - 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].

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


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


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
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.


9.1.1successful-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.


9.2 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:


  4. was not consumed OR


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


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


9.2.1client-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 8.1.2 for
further details.


9.2.2successful-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.


10.1Encoding 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"








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10.2Encoding 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.


11 Conformance Requirements

This section defines conformance requirements for Printers and
Notification Recipients.


11.1Printer Conformance Requirements


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


If the Printer supports the 'indp' Delivery Method, the Printer MUST:


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


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


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


5.support sending Event Notification via email with the content
  specified in section 8.1.1.



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11.2Notification Recipient Requirements


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


12 IANA Considerations

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


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.


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.

14.1Security 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


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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

[ipp-iig]
     Hastings, T., Manros, C., Kugler, K, Holst H., Zehler, P.,
     "Internet Printing Protocol/1.1:  draft-ietf-ipp-implementers-
     guide-v11-01.txt, work in progress, May 9, 2000

[ipp-mod]
     R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
     "Internet Printing Protocol/1.1: 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-04.txt>,
     August 30, 2000.

[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.






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[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
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.




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This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.













































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