INTERNET-DRAFT
<draft-ietf-ipp-not-spec-00.txt>
                                                             S. Isaacson
                                                            Novell, Inc.
                                                               J. Martin
                                                              Underscore
                                                                R. deBry
                                               Utah Valley State College
                                                             T. Hastings
                                                       Xerox Corporation
                                                             M. Shepherd
                                                       Xerox Corporation
                                                              R. Bergman
                                                      Dataproducts Corp.
                                                         August 25, 1999

  Internet Printing Protocol/1.1: Event Notification Specification

    Copyright (C) The Internet Society (1999). 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 IPP/1.0 & IPP/1.1 model that
allows a client to subscribe to printing related events. Subscriptions
include "Per-Job Submission subscription" and "Per-Printer
subscriptions".  One or more Per-Job Submission subscriptions are
specified by the client when submitting a job.  One or more Per-Printer
subscriptions are created by performing separate explicit Create-
Printer-Subscription operations on the Printer.  Four other operations
are defined for Per-Printer subscription objects:  get attributes, get
subscriptions, renew a subscription, and cancel a subscription.

A subscription includes:  the names of Job and/or Printer events, the
Notification Recipient URL, the Notification content MIME type, possibly
some opaque data and the charset and natural language.  In addition, the
Per-Printer subscription includes:  the requested lease time and
persistency for the subscription.  When the event occurs, a notification
is generated and delivered using the information specified in the
subscription.


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The full set of IPP documents includes:

  Design Goals for an Internet Printing Protocol [IPP-REQ]
  Rationale for the Structure and Model and Protocol for the Internet
     Printing Protocol [IPP-RAT]
  Internet Printing Protocol/1.1: Model and Semantics  [IPP-MOD]
  Internet Printing Protocol/1.1: Encoding and Transport [IPP-PRO]
  Internet Printing Protocol/1.0: Implementer's Guide [IPP-IIG]
  Mapping between LPD and IPP Protocols [IPP LPD]

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.  Operator and administrator requirements are out
of scope for version 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
specifications, and gives background and rationale for the IETF working
group's major decisions.

The "Internet Printing Protocol/1.1: Model and Semantics", 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.  It defines the encoding rules for a
new Internet MIME media type called "application/ipp".  This document
also defines the rules for transporting over HTTP a message body whose
Content-Type is "application/ipp".  This document defines a new scheme
named 'ipp' for identifying IPP printers and jobs.  Finally, this
document defines interoperability rules for supporting IPP/1.0 clients.

The "Internet Printing Protocol/1.0: Implementer's Guide" document gives
insight and advice to implementers of IPP clients and IPP objects.  It
is intended to help them understand IPP/1.0 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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                           Table of Contents

1 Introduction.......................................................6

  1.1Notification Overview..........................................6

2 Model for Per-Job and Per-Printer Subscription and Event Notification
  9

  2.1Model for Per-Job Subscription and Notification................9
  2.2Model for Per-Printer Subscription and Notification...........10
  2.3Relationship between the Printer object and the Notification
  Delivery Service..................................................11

3 Terminology.......................................................12

  3.1Conformance Terminology.......................................12
  3.2Other terminology.............................................12

4 Object Model for Notification.....................................15

  4.1Object relationships..........................................16

5 Object attributes defined for Notification........................17

  5.1"job-notify" (1setOf collection) Job Description attribute....17
  5.2Subscription object attributes................................18
  5.3Common Per-Job and Per-Printer Subscription attributes........19
     5.3.1 notify-recipient (uri)...................................20
     5.3.2 notify-events (1setOf type2 keyword).....................20
     5.3.3 notify-content-type (mimeMediaType)......................23
     5.3.4 subscriber-user-data (octetString(63))...................24
     5.3.5 notify-attributes-charset (charset)......................24
     5.3.6 notify-attributes-natural-languages (naturalLanguage)....24
     5.3.7 request-id...............................................24
  5.4Additional attributes for the Subscription object only........24
     5.4.1 subscription-id (integer (1:MAX))........................24
     5.4.2 notify-lease-expiration-time (integer(0:MAX))............25
     5.4.3 printer-uri (uri)........................................25
     5.4.4 subscriber-user-name (name(MAX)).........................25
     5.4.5 notify-printer-up-time (integer(1:MAX))..................26
  5.5Printer Description Attributes related to Notification........26
     5.5.1 notify-schemes-supported (1setOf uriScheme)..............27
     5.5.2 notify-events-default (1setOf type2 keyword).............27
     5.5.3 notify-events-supported (1setOf type2 keyword)...........27
     5.5.4 max-events-supported (integer(5:MAX))....................27
     5.5.5 max-job-subscriptions-supported (integer(1:MAX)).........27
     5.5.6 max-printer-subscriptions-supported (integer(0:MAX)).....27
     5.5.7 notify-lease-time-supported (rangeOfInteger(0:MAX))......28
     5.5.8 notify-lease-time-default (integer(0:MAX))...............28
     5.5.9 persistent-jobs-supported (boolean)......................28
     5.5.10persistent-subscriptions-supported (boolean).............28
     5.5.11printer-state-change-time (integer(1:MAX))...............28
     5.5.12printer-state-change-date-time (dateTime)................28

6 Notification Content..............................................29

  6.1Notification content MIME media type formats..................29




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  6.2Notification content attributes common to Job and Printer events
      29
  6.3Additional Notification content attributes for Job events only 31
  6.4Additional Notification content attributes for Printer events
  only 32

7 Operations for Per-Job Subscriptions..............................32

  7.1Job Creation Operations (Create-Job, Print-Job, Print-URI) and
  Validate-Job......................................................33
  7.2Get-Printer-Attributes operation..............................34
  7.3Get-Job-Attributes operation..................................34
  7.4Set-Job-Attributes operation..................................35

8 Per-Printer Subscriptions and the Subscription object.............35

  8.1Create-Printer-Subscription operation.........................35
  8.2Get-Printer-Subscription-Attributes operation.................38
  8.3Get-Printer-Subscriptions operation...........................39
  8.4Renew-Printer-Subscription operation..........................39
  8.5Cancel-Printer-Subscription operation.........................40

9 Comparison of Per-Job Submission Subscriptions versus Per-Printer
Subscriptions........................................................41

10   Conformance Requirements........................................42

11   IANA Considerations.............................................42

12   Internationalization Considerations.............................42

13   Security Considerations.........................................43

14   Status Codes....................................................43

  14.1 client-error-uri-notification-scheme-not-supported (0x04??)..43
  14.2 server-error-too-many-subscriptions (0x04??).................44
  14.3 server-error-too-many-events (0x04??)........................44

15   References......................................................44

16   Author's Addresses..............................................45

17   Appendix C: Full Copyright Statement............................46



















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                                 Tables

Table 1 - Summary of Per-Job Subscription operations..................7

Table 2 - Summary of Per-Printer Subscription operations..............8

Table 3 - Job object 'job-notify' colletion member attributes........18

Table 4 - Subscription object attributes.............................19

Table 5 - Printer Description attributes associated with Notification26

Table 6 - Common Job and Printer Notification content attributes.....30

Table 7 - Additional Notification content attributes for Job events only
    .................................................................31

Table 8 - Additional Notification content attributes for Printer events
   only.............................................................32

Table 9 - Member attributes of the "job-notify" collection operation
   attribute........................................................33

Table 10 - Conformance Requirements for Operations...................42


                                Figures

Figure 1 - Client-Printer Per-Job Subscription and Notification Model.9

Figure 2 - Client-Server-Printer Per-Job Subscription and Notification
   Model............................................................10

Figure 3 - Client-Printer Per-Printer Subscription and Notification
   Model............................................................11

Figure 4 - Opaque Use of a Notification Service......................11


























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1  Introduction


This IPP notification specification is an extension to IPP/1.0 [RFC2568,
RFC2569].  This document in combination with the following documents is
intended to meet the notification requirements described in [ipp-not-
req]:

     Internet Printing Protocol/1.0 & 1.1:  "Collection Attribute
     Syntax" [ipp-coll]
     Internet Printing Protocol/1.0 & 1.1:  "Job Progress Attributes"
     [ipp-prog]
     Internet Printing Protocol/1.0 & 1.1:  "Notification Change
     History" [ipp-not-hist]

The rest of this document is laid out as follows:

     - The rest of Section 1.1 is an overview of IPP Notification.

     - Section 2 is the model for network entities that use IPP
     notification, including clients (desktop and servers), IPP Printers
     (servers and devices), and Notification Recipients.

     - Section 3 is the terminology used throughout the document.

     - Section 4 is the object model for notification, including Job,
     Printer, and Subscription objects.

     - Section 5 defines the notification attributes for each of the
     Job, Printer, and Subscription objects.

     - Section 6 defines the content of Human Consumable and Machine
     Consumable Event Notifications.

     - Sections 7, 8, and 9 define the Per-Job and Per-Printer
     Subscription mechanisms.

     - Section 10 and 11 define the conformance requirements and IANA
     requirements, respectively.

     - Section 12 - 14 cover Internationalization, Security, and Status
     codes.


1.1 Notification Overview

A client can establish an event notification subscription so that when
one of the specified events occurs, an asynchronous Notification is sent
to a specified Notification Recipient.

One or more Per-Job Submission subscriptions are specified by the client
when submitting a job.  One or more Per-Printer subscriptions are
created by performing separate explicit Create-Printer-Subscription
operations on the Printer.

A Per-Job or Per-Printer subscription includes:

  1. the names of Job and/or Printer events that are of interest to the
     Notification Recipient



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  2. the delivery method and address to use to deliver the notification
     to one Notification Recipient

  3. whether Human Consumable or Machine Consumable notification content
     is to be sent

  4. some opaque data that the subscriber wants to be send to the
     Notification Recipient in the Notification, perhaps to identify
     either the subscriber or the ultimate recipient

  5. the charset to use in the Notification, if it is to be different
     than the one used in the request that created the subscription

  6. the natural language to use in the Human Consumable Notification,
     if it is to be different than the one used in the request that
     created the subscription

In addition, a Per-Printer subscription includes:

  7. the requested lease time in seconds for the subscription

  8. whether or not the subscription is requested to be persistent
     across power cycles.

For Per-Job subscriptions, a client requests job and printer event
notification using the "job-notify" operation attribute when creating a
job with any of the Job Creation operation: Print-Job, Print-URI, and
Create-Job.  The "job-notify" operation attributes may be submitted to
the Validate-Job in order to be validated.  The "job-notify" operation
attribute is copied to the Job object as a Job Description attribute and
so may be queried using the Get-Job-Attributes and Get-Jobs operations
(see [ipp-mod]).  Also this "job-notify" Job Description attribute may
be changed using the Set-Job-Attributes (see [ipp-set2]).  The "job-
notify" operation attribute contains one or more collection values, each
consisting of a number of member attributes the specify a subscription,
so that a Job can contain more than one Per-Job subscription.  The
'collection' is a new attribute syntax (see [ipp-coll]).  Table 1
summarizes the Per-Job Subscription operations and their salient input
operation attributes.  All operations are REQUIRED, except the Set-Job-
Attributes operation.

          Table 1 - Summary of Per-Job Subscription operations

     Operation:      salient inputs besides printer-uri:

     Print-Job,      1setOf {recipient, [events,] [content-type,]
     Print-URI,      [user-data,] [charset,] [natural-language]}
     Create-Job

     Validate-Job    1setOf {recipient, [events,] [content-type,]
                      [user-data,] [charset,] [natural-language]}

     Get-Job-        job-id, [requested-attributes]
     Attributes

     Set-Job-        job-id, 1setOf {[recipient,] [events,]
     Attributes      [content-type,] [user-data,] [charset,]
                      [natural-language]}




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For Per-Printer subscriptions, a client requests job and printer event
notification using new operations independent of any job.  The Printer
keeps each subscription in a separate Subscription object which is
similar to a Job object in its operations and security.  The Get-
Printer-Attributes (see [ipp-mod]) returns the supported notification
capabilities supported.  The Create-Printer-Subscription operation
creates an instance of the Subscription object supplying these new
operation attributes and returns a subscription-id (analogous to a job-
id for a Job object).  These operation attributes are copied to the
Subscription object as Subscription Description attributes and so may be
queried using the Get-Subscription-Attributes and Get-Subscriptions
operations.  The subscriber requests a lease time for each Per-Printer
subscription which MAY be infinite.  The Printer grants a lease time
according to its configured policy.  A client MUST renew the
Subscription before the granted lease time expires using the Renew-
Printer-Subscription operation.  Table 2 summarizes the Per-Printer-
Subscription operations and their salient input operation attributes.

        Table 2 - Summary of Per-Printer Subscription operations

     Operation:                salient inputs beside printer-uri:

     Get-Printer-Attributes    [requested-attributes]

     Create-Printer-           recipient, [events,] [content-
     Subscription              type,][user-
                                data,][charset,][natural-
                                language,][lease-time-requested,]
                                [persistence-requested]

     Get-Printer-              subscription-id, [requested-
     Subscription-Attributes   attributes]

     Get-Printer-              [my-printer-subscriptions,]
     Subscriptions             [requested-attributes]

     Renew-Printer-            subscription-id, [lease time-
     Subscription              requested]

     Cancel-Printer-           subscription-id
     Subscription


There are two steps that IPP notification must take regarding each event
. an internal event recording, and an external notification:

     1) As an events occurs, the printer internally records in the job
     objects and the printer objects those events which are required to
     be supported by the system and those that are subscribed to by a
     notification recipient.

     2) As an events occurs, the Printer searches the set of
     subscriptions for any interest in that event.  As the Printer finds
     that some notification recipient is interested in that event (the
     notification recipient is subscribed to the event), the "request-
     id" sequence number for that event is incremented and a
     notification is generated and delivered using the methods and
     target addresses identified in the subscription.  The "request-id"


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     sequence number permits a Notification Recipient to detect
     duplicate notifications due either to duplicate subscriptions or
     retries and to detect dropped notifications.


2  Model for Per-Job and Per-Printer Subscription and Event Notification


2.1 Model for Per-Job Subscription and Notification

Per-Job subscriptions are created by  a client (desktop or server acting
as a client) as part of creation of the job in an IPP Printer (printing
device or server)..  More than one subscription may be submitted with a
job.  The IPP Printer object delivers a Notifications to the
Notification Recipient supplied by the Client in each subscription.  A
Notification Recipient can be the Job submitter or a third party.

Figure 1 shows the Per-Job subscription notification model for a simple
Client - Printer relationship.


embedded printer:
                                        output device or server
     desktop or server                     +---------------+
        +--------+                         |  ###########  |
        | client |---IPP job submission------># Printer #  |
        +--------+  Per-Job subscription   |  # Object  #  |
                                           |  #####|#####  |
        +---------+                        +-------|-------+
        |recipient|<-----Notifications-------------+
        +---------+    (Job and/or Printer events)

 Figure 1 - Client-Printer Per-Job Subscription and Notification Model

Figure 2 shows a (spooling or non-spooling) Server that implements two
Printer objects (1 and 2) that represent two devices.  The devices A and
B in turn each implement an IPP Printer object (3 and 4, respectively).
The Server implementation has three choices for how to support Per-Job
subscriptions to the client (and itself):

     1.forward the Per-Job subscriptions to the down stream IPP Printer
       and let it perform the notification directly to the Notification
       Recipients supplied by the Client (Notifications(C)) and use
       Per-Printer Subscriptions for the Server's own purposes.

     2.save the client-supplied Per-Job subscription on the Job object
       in the server and substitute its own Per-Job subscription with
       the Server as the Notification Recipient (Notifications(B)).
       Then the Server relays Notifications to the client-supplied
       Notification Recipients (Notifications(A)).

     3.A combination of 1 and 2 in which the Server adds its own Per-
       Job subscriptions to those supplied by the client.  Thus the IPP
       Job that goes to Printer object 4 has a combination of
       subscription information from both the Client and the Server.
       This latter approach is sometimes called "piggy-backing" because



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       the Server is adding its Per-Job subscription information to
       that supplied by the client.  Piggy-backing is especially
       useful, if device B also accepts (IPP or non-IPP) requests from
       other servers.  Then when all the jobs from Server S have been
       completed by device B, there will be no more Job events sent to
       Server S.  (Server S could still maintain a long term Per-
       Printer subscription with Printer D to that Server S can have
       Printer B's state track (shadow) that of Printer D or Server S
       could poll Printer D when queried about Printer B).


                                                          device A
                           server S                    +------------+
                        +------------+                 | ###########|
+--------+   IPP Job    | ###########|    IPP Job      | # Printer #|
| client |--submission---># Printer #|---submission-----># Object 3#|
+--------+   Per-Job    | # Object 1#|    Per-Job      | ###########|
           subscription | ###########|   subscription  +------------+
                        |            |                    device B
+--------+   IPP Job    | ###########|                 +------------+
| client |--submission---># Printer #|    IPP Job      | ###########|
+--------+   Per-Job    | # Object 2#|---submission-----># Printer #|
           subscription | ###|#######|    Per-Job      | # Object 4#|
                        +----|---^---+   subscription  | ####|#|####|
+--------+                   |   |                     +-----|-|----+
|Notific-|<-Notifications(A)-+   +--- Notifications(B)-------+ |
|ation Re|<----------------Notifications(C)--------------------+
|cipient |
+--------+

 Figure 2 - Client-Server-Printer Per-Job Subscription and Notification
                                 Model


2.2 Model for Per-Printer Subscription and Notification

Per-Printer subscriptions are created by a client (an end user, an
operator, or a server acting as a client) using a Create-Printer-
Subscription operation that is independent of Job Submission.  The
Printer object (printing device or server) creates a Subscription object
to hold the attributes supplied by the subscriber.  The client creates
separate Per-Printer subscriptions if more than one Notification
Recipient is desired.  The Printer delivers Notifications to the
Notification Recipient specified by each Per-Printer subscription.  A
Notification Recipient may be the subscriber or a third party.  Figure 3
shows the Per-Printer subscription notification model for the Client -
Printer relationship where the client may be an end user, an operator,
or a server acting as a client.









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       desktop or server                    server or printing device
                                              +---------------+
           +--------+                         |  ###########  |
           | client |---IPP job submission------># Printer #  |
           +--------+  Per-Job subscription   |  # Object  #  |
                                              |  #####|#####  |
           +---------+                        +-------|-------+
           |recipient|<-----Notifications-------------+
           +---------+    (Job and/or Printer events)

  Figure 3 - Client-Printer Per-Printer Subscription and Notification
                                 Model


2.3 Relationship between the Printer object and the Notification
    Delivery Service

 The IPP Notification model does not mandate that the IPP Printer object
implement the full semantics of subscription, report generation, and
multiple delivery methods itself.  An implementation may be configured
to use some other notification service.  Figure 4 shows this
partitioning.


           Create Request with              ###########
       ----Subscriptions-------------------># IPP     #
                                            # Printer #
                                            # Object  #
                                            ###########
                                                |
                                         *******|**********
                                       *    Subscriptions   *
                                     *       & Events        *
                                   *            |
                                  *        +----v---------+
                                 *         | notification |
       <---Job and Printer ------*---------| service      |
           Notifications         *         +--------------+
                                 *
                                 *

     *** = Implementation configuration opaque boundary


            Figure 4 - Opaque Use of a Notification Service

If an IPP Printer does use some other notification service, it MAY do so
in either of two ways:

     1.The IPP Printer forwards the Subscriptions and the Events to the
       other notification service which then sends the Notifications to
       the proper Recipients.

     2.The IPP Printer keeps the subscriptions and uses them to send
       Notifications to the other notification service which forwards



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       them to Recipients that have also subscribed directly with the
       other notification service.  Examples of this latter approach
       are paging and immediate messaging services.

In any case, the interface between the IPP Printer and the other
notification service is outside the scope of this document and is
intended to be transparent to this specification.


3  Terminology


This section defines terminology used throughout this document.


3.1 Conformance Terminology

  Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD, SHOULD
     NOT, MAY, NEED NOT, and OPTIONAL, have special meaning relating to
     conformance to this specification.  These terms are defined in
     [ipp-mod section 13.1 on conformance terminology, most of which is
     taken from RFC 2119 [RFC2119].
          Since support of this entire notification specification is
          OPTIONAL for conformance to IPP/1.0 or IPP/1.1, the use of the
          term REQUIRED in this document means "REQUIRED if this
          notification specification is implemented".  Likewise, the
          term RECOMMENDED means "RECOMMENDED if this notification
          specification is implemented".
  READ-ONLY - indicates an attribute that MUST NOT be settable using
     the Set-Job-Attributes or Set-Printer-Attributes operations (see
     [ipp-set2]).

3.2 Other terminology

  Job Submitting End User  - A human end user who submits a print job
     to an IPP Printer.  This person may or may not be within the same
     security domain as the Printer. This person may or may not be
     geographically near the printer.
  Administrator - A human user who established policy for and
     configures the print system.
  Operator - A human user who carries out the policy established by the
     Administrator and controls the day to day running of the print
     system.
  Job Submitting Application - An application (for example, a batch
     application), acting on behalf of a Job Submitting End User, which
     submits a print job to an IPP Printer. The application may or may
     not be within the same security domain as the Printer. This
     application may or may not be geographically near the printer.
  Security Domain - The set of network components which can communicate
     without going through a proxy or firewall. A security domain may be
     geographically very large, for example - anyplace within IBM.COM.
  IPP Client (or client) - The software component (desktop or server)
     that sends an IPP operation request to an IPP Printer object
     (server or printing device) and accepts the resulting operation
     response from the IPP Printer object.. Job Recipient - A human who
     is the ultimate consumer of the print job. In many cases this will


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     be the same person as the Job Submitting End User, but need not be.
     Example:  If I use IPP to print a document on a printer in a
     business partner's office, I am the Job Submitting End User, while
     the person I intend the document for in my business partner's
     office is the Job Recipient.  Since one of the goals of IPP is to
     be able to print near the Job Recipient of the printed output, we
     would normally expect that person to be in the same security domain
     as, and geographically near, the Printer. However, this may not
     always be the case. For example, I submit a print job across the
     Internet to a Kinko's print shop. I am both the Submitting End User
     and the Job Recipient, but I am neither near nor in the same
     security domain as the Printer.
  Job Recipient Proxy  - A human acting on behalf of the Job Recipient.
     In particular, the Job Recipient Proxy physically picks up the
     printed document from the Printer, if the Job Recipient cannot
     perform that function. The Proxy is by definition geographically
     near and in the same security domain as the printer.
     Example:  I submit a print job from home to be printed on a printer
     at work. I'd like my secretary to pick up the print job and put it
     on my desk. In this case,  I am acting as both Job Submitting End
     User and Job Recipient. My secretary is acting as a Job Recipient
     Proxy
  Notification Subscriber (or Subscriber) - A client that requests the
     IPP Printer to send Event Notifications to one or more Notification
     Recipients.  A Notification Subscriber may be:
     1.a Job Submitting End User or Job Submitting Application (desktop
       or server) that is submitting a job or
     2.an End User, an Operator, or an Administrator that is not
       submitting a job.
  Subscription  - A request by a Notification Subscriber to the IPP
     Printer to send Event Notifications to a specified Notification
     Recipient when the event occur.  A Subscription is represented as a
     set of attributes that indicate the "what, where, who, and how" for
     notification.  Notifications are generated for certain events
     (what) and delivered using various delivery methods (how) to
     certain addresses (where and who).
  Per-Job Subscription - A Subscription that a client specifies as part
     of a create job operation (Print-Job, Print-URI, Create-Job), or a
     Validate-Job operation.
  Per-Printer Subscription - A Subscription that a client specifies
     using an explicit  Create-Printer-Subscription operation, that is
     attached to a Printer object.
  Notification Source - The entity that sends Event Notifications.
  Notification Recipient  - The entity identified as a recipient within
     a subscription that receives IPP Notifications about Job and/or
     Printer events.   A Notification Recipient may be a: Job Submitting
     End User,  Job Submitting Application (desktop or server), Job
     Recipient, Job Recipient Proxy, Operator, or Administrator, etc.,
     and their representative or log file or usage statistics gathering
     application or other active or passive entities.
  Notification Recipient Agent  - A program which receives
     Notifications on behalf of the Notification Recipient. The agent



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     may take some action on behalf of the recipient, forward the
     notification to the recipient via some alternative means (for
     example, page the recipient), or queue the notification for later
     retrieval by the recipient.
  Event  - An event is some occurrence (either expected or unexpected)
     within the printing system of a change of state, condition, or
     configuration of a Job or Printer object.  A property of an event
     is that it only occurs at one instant in time and does not span the
     time the physical event takes place.  For instance, jam-occurred
     and jam-cleared are two distinct events.  The jam-occurred event is
     reported only when the jam initially occurs and only if there is
     one or more event subscriptions outstanding for that event.

     Events can be classified along two dimensions:
       - Either as Job Events or Printer Events, and
       - Either as Errors, Warnings, or Reports

     A Job event is some interesting state change in the Job object, and
     a Printer event is some interesting change in the Printer object.

     A report event is purely informational, such as 'job-completed' or
     'accepting-jobs'.  A warning is not serious and processing
     continues.  An error is serious and either the job is aborted or
     the printer stops.  These are typical uses of the terms report,
     warning, and error, although the actual usage is implementation
     dependent.

     An event occurs for a job or printer whether any entity has
     subscribed to be notified for that event or not.  A notification is
     only generated depending on the set of subscriptions outstanding.

  Notification  - When an event occurs, a Notification is generated
     that fully describes the event (what the event was, where it
     occurred, when it occurred, etc.).  Notifications are delivered to
     each Notification Recipient that has a subscription that includes
     the event, if any.  The Notification is delivered to the address of
     the Notification Recipient using the notification delivery method
     defined in the subscription.  However, a Notification is sent ONLY
     if there is a corresponding subscription.
  Notification Delivery Method (or Delivery Method for short) -
     Notifications are delivered using a method, such as email, TCP/IP,
     etc.
  Immediate Notification - Notifications that are delivered using a
     delivery method which is not store-and-forward (e.g. TCP
     connection, UDP datagram). This can be on the order of several
     minutes subject to network latency.
  Store and Forward Notification  - A Notification which are not
     necessarily delivered to Notification Recipients immediately, but
     is queued for delivery by some intermediate network application,
     for later retrieval.  Email is an example of a store and forward
     notification delivery method.




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  Human Consumable Notification - Notifications that are intended to be
     consumed by human End Users only.  They are simple text that has
     been localized for the Notification Recipient as specified in the
     subscription.  Programs are not intended to parse Human Consumable
     Notification, since it is localized and the content depends on
     implementation.  There is no standardized format.
  Machine Consumable Notification - Notifications that are intended for
     consumption by a program only.  They use the encoding of an IPP
     response.  The Notification Recipient must localize the contents,
     if displaying it to a human.

4  Object Model for Notification


This section describes the notification object model that adds a
REQUIRED Subscription object which together with the Job and Printer
object provide the complete notification semantics.

Per-Job subscriptions do not use the Subscription object.  Instead, a
Job can have one or more Per-Job subscription which is represented
entirely as a single Job attribute.  Each Per-Job subscription is
represented as a collection value of the "job-notify" Job attribute.


































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The object relationships can be seen pictorially as:


   Subscription objects (Per-Printer Subscriptions)     Printer object
   +----+                                                +------------+
   | s1 |<---------------------------------------------->|            |
   +----++                                               |            |
    | s2 |<--------------------------------------------->|     p1     |
    +----++                                              |            |
     | s3 |<-------------------------------------------->|            |
     +----+                                              +------------+
                    Job objects
                     +---------+
                     |         |
                     |   j1    |
                     |         |
                     +----+    |
                     | s4 |    |      s4 is a Per-Job subscription
                     ++---+----++
                      |         |
                      |   j2    |
                      |         |
                      +----+----|
                      | s5 | s6 |     s5 and s6 are Per-Job
subscriptions
                      ++---+----++
                       |         |
                       |   j3    |
                       |         |
                       |         |
                       +---------+

                Figure 5 - Object Model for Notification

     s1, s2, and s3 are Per-Printer Subscription objects and can
     identify Printer and/or Job events.

     s4, s5, and s6 are Per-Job subscriptions (not objects) and can
     identify Printer and/or Job events.


4.1 Object relationships

The object relationships can be stated as follows:

  1. The Printer object contains zero or more Subscription objects (p1
     contains s1-s3 Subscription objects).

  2. Each Subscription object (s1, s2, and s3) is contained in one
     Printer object (p1) and represents one Per-Printer subscription.

  3. Each "Per-Printer" Subscription object identifies one or more Job
     and/or Printer events.  Such Job events are for all jobs on the
     Printer.  Such Printer events are for any Printer event, no matter
     which job is processing and when no jobs are processing.





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  4. Each "Per-Job" subscription (not an object by itself, but is
     attributes of the Job object) identifies one or more Job and/or
     Printer events.  Such Job events are only for this job (different
     than "per-Printer" Subscriptions).  Such Printer events are for any
     Printer event, no matter which job and when no jobs are processing
     (same as for "per-Printer" Subscriptions).

  5. A Job object contains zero or more Per-Job subscriptions (not an
     object).  Job j1 contains Per-Job subscription s4, Job j2 contains
     Per-Job subscription s5 and s6, and Job j3 does not contain a Per-
     Job subscription.

  6. A Subscription object cannot be contained in or associated with
     more than one Printer object.

  7. A Per-Job subscription cannot be contained in or associated with
     more than one Job object.


5  Object attributes defined for Notification


The following notification attributes are defined for each of the
Printer, Job, and Subscription objects.  The definitions of the object
attributes are specified here so that they can be referred to from the
subsequence definitions of the operations that set them.


5.1 "job-notify" (1setOf collection) Job Description attribute

In order to permit more than one Per-Job subscription, each subscription
is represented as a collection value of the "job-notify (1setOf
collection)" Job Description attribute.  An implementation MUST support
at least one collection value of the "job-notify" attribute.  Table 3
lists the member attributes of the "job-notify" attribute.  Section 5.3
defines each of the "job-notify" member attributes.

The "job-notify" Job Description attribute MAY be modified by the Set-
Job-Attributes operation (see section 7.4) in which case all of its
member attributes are replaced and the READ-ONLY "request-id" member
attribute is reset with a value of '0' (see section 5.3.7).


















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     Table 3 - Job object 'job-notify' colletion member attributes

   Job object attributes:         Print set by:
                                   er
                                   suppo
                                   rt

   notify-recipient (uri)         R     job creation operation,
                                          Set-Job-Attributes

   notify-events (1setOf type2    R     job creation operation,
   keyword)                              Set-Job-Attributes

   notify-content-type            R     job creation operation,
   (mimeMediaType)                       Set-Job-Attributes

   subscriber-user-data           R     job creation operation,
   (octetString(63))                     Set-Job-Attributes

   notify-charset (charset)       O     job creation operation,
                                          Set-Job-Attributes

   notify-natural-languages       O     job creation operation,
   (naturalLanguage)                     Set-Job-Attributes


   request-id (integer(0:MAX))    R     Printer - event
                                          occurring



5.2 Subscription object attributes

Each Per-Printer subscription is contained in a separate Subscription
object.  An implementation MUST support at least one Subscription object
instance.  Table 4 lists the Subscription attributes defined for the
Subscription object.  Sections 5.3 and 5.4 define each of the
Subscription attributes.

All of the Subscription object attributes are READ-ONLY.  They are set
by other operations.




















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                Table 4 - Subscription object attributes

   Subscription object attributes:    Print READ-ONLY, set by:
                                       er
                                       suppo
                                       rt

   notify-recipient (uri)             R     client - Create-Printer-
                                              Subscription

   notify-events (1setOf type2        R     client - Create-Printer-
   keyword)                                  Subscription

   notify-content-type                R     client - Create-Printer-
   (mimeMediaType)                           Subscription

   subscriber-user-data               R     client - Create-Printer-
   (octetString(63))                         Subscription


   notify-charset (charset)           O     client - Create-Printer-
                                              Subscription

   notify-natural-languages (1setOf   O     client - Create-Printer-
   naturalLanguage)                          Subscription


   request-id (integer(0:MAX))        R     Printer - event occurring




Not in a Per-Job subscription:

   subscription-id (integer(1:MAX))   R     Printer - Create-Printer-
                                              Subscription

   notify-lease-expiration-time       R     Printer - Create-Printer-
   (integer(0:MAX))                          Subscription,
                                              Renew-Printer-
                                              Subscription

   printer-uri (uri)                  R     Printer - Create-Printer-
                                              Subscription

   subscriber-user-name (name(MAX))   R     Printer - Create-Printer-
                                              Subscription


   notify-printer-up-time             R     Printer - returned by
   (integer(1:MAX))                          Get-Printer-Subscription-
                                              Attributes and Get-
                                              Printer-Subscriptions


5.3 Common Per-Job and Per-Printer Subscription attributes

The following sub-sections define attributes that are in common to both
Per-Job and Per-Printer subscriptions, i.e., are member attributes of
the "job-notify" collection Job Description attribute and are
Subscription object attributes.  Section 5.4 defines additional
attributes that are only Subscription object attributes.


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5.3.1 notify-recipient (uri)

This REQUIRED attribute describes both where (the address of the
Notification Recipient) and how (the delivery method) notifications are
to be delivered to the Notification Recipient when any of the events
specified in the "notify-events" attribute occur.

There are potentially many different notification delivery methods for
IPP notifications, standardized as well as proprietary.  This document
does not define any of these delivery mechanisms;  they will each be
described in separate complementary documents.

Each of the notification delivery method documents must provide at least
the following information:

  1) The URI scheme used.

  2) The supported and default delivery format, and if not one of the
     specified types in Section 5.3.3, description of the notification
     content.

  3)Any content length restrictions imposed by the delivery protocol.

  4) The latency of the delivery protocol used.

  5)The reliability of the transport and delivery protocol used.

  6)  The security aspects of the transport and delivery protocol used,
     e.g. how it is handled in firewalls.

  7) How the delivery protocol is initiated, e.g. does it have to be
     initiated by the receiving user (pull), or is it initiated by the
     notification service (push).

ISSUE 1: Once a number of delivery solutions have been developed and
evaluated, we may want to make one or several of them REQUIRED for
implementation to ensure a minimum set of interoperability.  Which one
or ones should be REQUIRED?


5.3.2 notify-events (1setOf type2 keyword)

This REQUIRED attribute identifies the job and/or printer events that
are to be delivered to the Notification Recipient as Notifications as
defined in section 6.  If the client did not supply this attribute when
supplying the subscription, the Printer object populates this attribute
with its "notify-events-default" attribute value (see section 5.5.2).

There are both job events and printer events.  Each job and printer
event is assigned a keyword to use in this attribute and in the
Notification.

The events are defined to be disjoint.

A Printer MUST support the events indicated as "REQUIRED".

The standard job event keyword values are:

  'none':  REQUIRED - no notifications of any events (an IPP object can
     use this value to indicate that it is configured not to support
     event notification; a client would not subscribe to this event).


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  'job-created':  REQUIRED - the Printer object has accepted  a job
     creation operation (Print-Job, Print-URI, or Create-Job) and the
     job's "time-at-creation" attribute value is set (see [ipp-mod]
     section 4.3.14.1).  The Printer puts the job in the 'pending',
     'pending-held' or 'processing' states.
     Note:  This event is separate from the 'job-state-changed' event so
     that it can be subscribed to without having to get every job state
     change event for a Notification Recipient that is only interested
     in when the job is first created.
  'job-completed':  REQUIRED - the job has reached one of the completed
     states, i.e., the value of the job's "job-state" attribute has
     changed to: 'completed', 'aborted', or 'canceled'.  The Job's
     "time-at-completed" and "date-time-at-completed" (if supported)
     attributes are set (see [ipp-mod] section 4.3.14).
     Note:  This event is separate from 'job-state-changed' so that it
     can be subscribed to without having to get every job state change
     event for a Notification Recipient that is only interested in when
     the job is completed.
  'job-state-changed':  REQUIRED - the job has changed from any state
     to any other state and/or a value has been added or removed from
     the job's "job-state-reasons" attribute, except when the job is
     created or when the job moves to any of the "completed" job states
     ('completed', 'aborted', or 'canceled').

     This event also indicates that one or more values have been added
     to or removed from the Job's "job-state-reasons" attribute, such as
     'job-queued' or 'job-printing', whether or not the job's state has
     changed.  If job state reasons are added when the job is created,
     only the 'job-created' event is generated, in order to keep the
     events disjoint.  If job state reasons are added or removed when
     the job is completed, only the 'job-completed' event is generated,
     in order to keep the events disjoint.

     A client that wants to subscribe to all job state changes,
     including creation and completion, includes the 'job-created',
     'job-state-changed', and 'job-completed' in the notification
     subscription.  When a job is finally removed from the Job History
     (see [ipp-mod] 4.3.7.1) no event is generated, i.e., neither a
     'job-state-changed' event nor a 'job-purged' event is generated.
  'job-config-changed':  OPTIONAL . when the configuration of a job has
     changed, i.e., the value of the "job-message-from-operator" or any
     of the non-READ-ONLY Job attributes have changed, such as any of
     the job template attributes or the "job-name" attribute.
     Typically, such a change is the result of the user or the operator
     performing a Set-Job-Attributes operation (see [ipp-set2]) on the
     Job object.  The client performs a Get-Job-Attributes to find out
     the new values of the changed attributes.  This event is useful for
     GUI clients and drivers to update the job information to the user.
  'job-purged':  OPTIONAL - when a 'not-completed' job (i.e., not
     'completed', 'canceled', or 'aborted') was purged from the printer
     using the Purge-Jobs operation.  No event, including this event, is




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     generated when a job is aged out of the Job History or moved out
     explicitly with the Purge-Jobs operation.
  'job-progress' - a sheet or copy has completed.  See separate [ipp-
     prog] spec.


The standard Printer event keywords values are:

  'none':  REQUIRED - no notification of any events (an IPP object can
     use this value to indicate that it is configured not to support
     event notification; a client would not subscribe to this event).
  'printer-restarted':  OPTIONAL - when the printer is powered up or
     the Restart-Printer operation is performed (see [ipp-set2]).
     Note:  This event is separate from the 'printer-state-changed'
     event so that it can be subscribed to without having to get every
     printer state change event, for a Notification Recipient that is
     only interested in when the Printer first comes up.
  'printer-shutdown':  OPTIONAL - when the device is being powered down
     or the Shutdown-Printer operation has been performed with either
     power-off or standby options (see [ipp-set2]).
     Note:  This event is separate from 'printer-state-changed' so that
     it can be subscribed to without having to get every Printer state
     change event, for a Notification Recipient that is only interested
     in when the Printer is powered down or shutdown.
  'printer-state-changed':  REQUIRED - the Printer changed state, i.e.,
     the value of the Printer's "printer-state", "printer-state-reasons"
     (whether "printer-state" changed or not), and/or "printer-is-
     accepting-jobs" attributes changed, except when the Printer starts
     up or is shutdown.  If printer state reasons are added when the
     Printer is started up, only the 'printer-restarted' event is
     generated, in order to keep the events disjoint.  If printer state
     reasons are added or removed when the printer is powered-down or
     shutdown, only the 'printer-shutdown' event is generated, in order
     to keep the events disjoint.

     A client that wants to subscribe to all printer state changes,
     including restart and power-down/shutdown, includes the 'printer-
     restarted', 'printer-state-changed', and 'printer-shutdown' in the
     notification subscription.
  'printer-media-changed':  OPTIONAL . when the media loaded on a
     printer has been changed, i.e., the "media-ready" attribute has
     changed.  This event includes both an actual media change and
     filling an empty input tray with the same or different media.  The
     client must check the "media-ready" Printer attribute (see [ipp-
     mod] section 4.2.11) separately to find out what new media was
     loaded or filled.
  'printer-config-changed':  OPTIONAL . when the configuration of a
     Printer has changed, i.e., the value of the "printer-message-from-
     operator" or any non-READ-ONLY Printer attribute has changed,
     except for "media-ready" (which has its own event), whether through
     the Set-Printer-Attributes operation or by other means and whether
     initiated by a human or not.  For example, any "xxx-supported",
     "xxx-default", "printer-message-from-operator", etc. values have
     changed.  The client has to perform a Get-Printer-Attributes to


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     find out the new values of these changed attributes.  This event is
     useful for GUI clients and drivers to update the available printer
     capabilities to the user.
  'printer-queue-changed': OPTIONAL - the order of jobs in the
     Printer's queue has changed, so that an application that is
     monitoring the queue can perform a Get-Jobs operation to determine
     the new order.  This event does not include when a job enters the
     queue (the 'job-created' event covers that) and does not include
     when a job leaves the queue (the 'job-completed' event covers
     that).
  'printer-no-longer-full':  OPTIONAL . when the Printer can now accept
     a Print-Job, Print-URI, Create-Job, Send-Document, or Send-URI
     request.  This event is used when there is more than one client
     feeding a printer/server (fan-in), and the Printer may still be
     printing but has acquired more buffer space to accept jobs.  This
     event only occurs when the Printer did not have room to accept jobs
     previously and rejected a Print-Job, Print-URI, Create-Job, Send-
     Document, or Send-URI operation.
  'printer-almost-idle':  OPTIONAL . when the Printer needs another Job
     in order to stay busy.  This event is used when a spooler is
     feeding more than one printer/server (fan-out), and the spooler
     holds jobs until a Printer requests them, rather than committing
     jobs to IPP Printers before it is necessary.  This event MAY be
     used by a Printer implementation to request a new job from any
     subscribers sufficiently ahead of time so that the device does not
     run out of work between jobs.


5.3.3 notify-content-type (mimeMediaType)

This REQUIRED attribute specifies the type of content that is to be sent
in the notifications.  Thus the subscriber can control whether the event
notification content is Human Readable or Machine Readable.  Most
delivery methods support both forms of content type and MUST define one
of them as the default.  If a delivery method only supports one form of
content type, then that form is also the default.

If the MIME media type registration permits a charset parameter, than
such a specification MUST be used (instead of the "notify-charset"
attribute) in order to indicate the charset to be used in the
notification content.

If the Subscriber did not supply this attribute when requesting the
subscription, the Printer object populates this attribute from the
default value defined for the delivery method.

Standard mimeMediaType values are:

     'application/ipp' - the Machine Consumable notification content
          using the 'application/ipp' MIME media type [ipp-mod] as
          defined in section 6.

     'text/plain; charset=utf-8':  A plain text document in ISO 10646
          represented as UTF-8 [RFC-2044] as defined in section 6.




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5.3.4 subscriber-user-data (octetString(63))

This REQUIRED attribute holds opaque information being sent from the
Subscriber to the Notification Recipient, such as the identify of the
Subscriber or a path or index to some Subscriber information.  Or it MAY
contain a key that the Notification Recipient needs in order to process
the Notification, such as the ultimate recipient, if the Notification
Recipient is a general application that in turn forwards notifications.

5.3.5 notify-attributes-charset (charset)

This OPTIONAL attribute specifies the charset to be used in the
Notification content sent to the notification recipient.  This attribute
MUST NOT be used when the "notify-content-type" attribute value
specifies the charset parameter in its MIME media type value.

5.3.6 notify-attributes-natural-languages (naturalLanguage)

This OPTIONAL attribute specifies the natural language for the IPP
object to use in the Notification content that is sent to the
Notification Recipient.

5.3.7 request-id

This REQUIRED READ-ONLY attribute holds the most recent request-id
sequence number delivered in a Notification content to the Notification
Recipient.    A value of 0 indicates that no Notifications have been
sent for this subscription.  The first request-id sent for a
subscription MUST be 1.  Each Notification Recipient has its own
monotonically increasing series of request-ids, i.e., no gaps, in order
to be able to detect a missing notification.

For a Per-Job subscription, "request-id" is a READ-ONLY member attribute
of each collection value.  All of the other member attributes (see
section 5.1) are not READ-ONLY and MAY be modified by a Set-Job-
Attributes operation (see 7.4).


5.4 Additional attributes for the Subscription object only

The following sub-sections define additional attributes that are only
for the Subscription object and have no counter part in Per-Job
subscriptions.

5.4.1 subscription-id (integer (1:MAX))

This REQUIRED READ-ONLY Subscription object attribute uniquely
identifies this Subscription object instance on this Printer.  The
Printer object, on acceptance of a Create-Printer-Subscription request,
generates an ID which identifies the new Subscription object on that
Printer.  The Printer returns the value of the "subscription-id"
attribute as part of the response to a Create-Printer-Subscription
request.  The 0 value is not included to allow for compatibility with
"job-id" and with SNMP index values which also cannot be 0.

It is RECOMMENDED that Per-Printer Subscription objects be persistent.
Then the Subscription objects including the subscription-id remains
unique across power-cycles.  Even if an implementation does not make
Per-Printer subscription objects persist, the implementation SHOULD make


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every attempt not to re-use subscription ids that subscribers might
still think are valid.  In other words, the Printer SHOULD at least keep
the next subscription-id to be assigned in non-volatile memory.

5.4.2 notify-lease-expiration-time (integer(0:MAX))

This REQUIRED READ-ONLY Subscription object attribute specifies the time
in the future when the subscription lease will expire, i.e., the
"printer-up-time" value at which the lease will expire.  When the
Printer object creates a Subscription object, it populates this
attribute with the appropriate value.  When the indicated time arrives,
the Printer MUST delete the Per-Printer Subscription object.

A client is able to extend a lease using the Renew-Printer-Subscription
operation (see section 8.4).  A value of 0 indicates an infinite time,
if such a policy is supported as indicated in the "notify-lease-time-
supported" (integer(0:MAX)) Printer Description attribute (see section
5.5.7) and the subscriber is authorized to request an infinite lease.

Note: In order to compute the number of seconds remaining in a Per-
Printer Subscription lease, a client can subtract the "notify-printer-
up-time" Printer object attribute (see section 5.4.5) from the "notify-
lease-time" Subscription object attribute.

5.4.3 printer-uri (uri)

This REQUIRED READ-ONLY Subscription object attribute identifies the
Printer object that created this Subscription object.  When a Printer
object creates a Subscription object, it populates this attribute with
the Printer object URI that was used in the create request.  This
attribute permits a client to identify the Printer object URI that was
used to create this Subscription object, i.e., what security scheme was
used.

5.4.4 subscriber-user-name (name(MAX))

This REQUIRED READ-ONLY Subscription object attribute contains the name
of the user that created the Subscription object.  The Printer object
sets this attribute to the most authenticated printable name that it can
obtain from the authentication service over which the IPP operation was
received.  This attribute is intended to help a human user determine for
which Per-Printer Subscriptions they are the Subscriber.  Only if such
is not available, does the Printer object use the value supplied by the
client in the "requesting-user-name" operation attribute of the create
operation (see [IPP-MOD] Sections 4.4.2, 4.4.3, and 8).

ISSUE 2 - What is the value of the "subscriber-user-name" when the
Subscriber is a server send a  job to an IPP Printer?  The original Job
Submitting End User use name or some "user name" that identifies the
Server?

Note:  The Printer object needs to keep an internal originating user id
of some form, typically as a credential of a principal, with the
Subscription object.  Since such an internal attribute is
implementation-dependent and not of interest to clients, it is not
specified as a Subscription Description attribute.  This originating



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user id is used for authorization checks (if any) on all subsequent
operations.

5.4.5 notify-printer-up-time (integer(1:MAX))

This REQUIRED READ-ONLY Subscription object attribute indicates the
amount of time (in seconds) that the Printer implementation has been up
and running.  This attribute is an alias for the Printer's "printer-up-
time" attribute" (see [ipp-mod] section 4.4.29), in an analogous way
that the Job's "job-printer-up-time" is an alias for "printer-up-time"
(see [ipp-mod] section 4.3.13.4).

Note:  A client can request this attribute in a Get-Printer-
Subscription-Attributes or Get-Printer-Subscriptions request and use the
value returned in combination with the "notify-subscription-expiration-
time" (see section 5.4.2) in order to display wall clock time equivalent
to the user.  The difference between this attribute and the 'integer'
value of the "notify-subscription-expiration-time" attribute is the
number of seconds in the future that the subscription will expire.  A
client can compute the wall-clock time at which the subscription will
expire by adding this difference to the client.s wall-clock time.


5.5 Printer Description Attributes related to Notification

This section defines the Printer Description attributes that are related
to Notification.

 Table 5 - Printer Description attributes associated with Notification

     Printer object attributes:         Printer READ-ONLY, set by:
                                         support

     notify-schemes-supported (1setOf   R       Administrator/implem
     uriScheme)                                  entation

     notify-events-default (1setOf      R       Administrator/implem
     type2 keyword)                              entation

     notify-events-supported (1setOf    R       Administrator/implem
     type2 keyword)                              entation

     max-events-supported               R       Administrator/implem
     (integer(5:MAX))                            entation

     max-job-subscriptions-supported    R       Administrator/implem
     (integer(1:MAX))                            entation

     max-printer-subscriptions-         R       Administrator/implem
     supported (integer(0:MAX))                  entation

     notify-lease-time-supported        R       Administrator/implem
     (rangeOfInteger(0:MAX))                     entation

     notify-lease-time-default          R       Administrator/implem
     (integer(0:MAX))                            entation

     persistent-jobs-supported          O       Administrator/implem
     (boolean)                                   entation

     persistent-subscriptions-supported O       Administrator/implem



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     Printer object attributes:         Printer READ-ONLY, set by:
                                         support

     (boolean)                                   entation

     printer-state-change-time          O       Administrator/implem
     (integer(1:MAX))                            entation

     printer-state-change-date-time     O       Administrator/implem
     (dateTime)                                  entation


5.5.1 notify-schemes-supported (1setOf uriScheme)

This REQUIRED Printer attribute describes the notification delivery
methods supported by this Printer object. Standard values are defined in
Section 5.3.1).

5.5.2 notify-events-default (1setOf type2 keyword)

This REQUIRED Printer attribute identifies the event values if the
client does not supply the "notify-events" operation attribute in either
a Job creation request or the Create-Printer-Subscription request.  Any
value in this attribute MUST also appear in the notify-events-supported
attribute, i.e., be a supported event.

5.5.3 notify-events-supported (1setOf type2 keyword)

This REQUIRED Printer attribute identifies the events supported by this
Printer object for both Per-Job and Per-Printer subscriptions which MUST
be the same.  Standard values are defined in Section 5.3.2.

5.5.4 max-events-supported (integer(5:MAX))

This REQUIRED Printer attribute specifies the maximum number of events
that are supported in a single Per-Job or Per-Printer subscription which
must be the same.  A Printer MUST support at least 5 events per
subscription, so that clients can depend on at least 5 events in a
single subscription.  If the number of events supplied by a client in a
subscription exceed this number, the Printer rejects the request and
returns the 'server-error-too-many-events (see section 14.3).  If
notification is not supported, this attribute MUST NOT be supported.

5.5.5 max-job-subscriptions-supported (integer(1:MAX))

This REQUIRED Printer attribute specifies the maximum number of Per-Job
subscriptions that are supported in a single Job Creation request, i.e.,
the maximum number of collection values for the "job-notify" operation
attribute.  A value of 0 indicates no effective maximum.  A Printer MUST
support at least 1 Per-Job subscription.  If the number of Per-Job
subscriptions supplied by a client in a Job Creation request exceed this
number, the Printer rejects the request and returns the 'server-error-
too-many-subscriptions' (see section 14.2).

5.5.6 max-printer-subscriptions-supported (integer(0:MAX))

This REQUIRED Printer attribute specifies the maximum number of Per-
Printer subscriptions that are supported by multiple Create-Printer-
Subscription requests, i.e., the maximum number of un-expired
Subscription objects that the Printer supports at a time.  A value of 0


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indicates no effective maximum.  A Printer MUST support at least 1 Per-
Printer subscription.  If the number of Per-Printer subscriptions would
exceed this number, the Printer rejects the Create-Printer-Subscription
request and returns the 'server-error-too-many-subscriptions' (see
section 14.2).

5.5.7 notify-lease-time-supported (rangeOfInteger(0:MAX))

This REQUIRED Printer attribute specifies the range of values in seconds
that are supported for the "notify-lease-time-requested" operation
attribute in a Create-Printer-Subscription or Renew-Printer-Subscription
request.  When the lease time expires for a Per-Printer Subscription
without renewing, the Printer MUST delete the Subscription object.  If
the client requests a value outside this range, the Printer MUST grant a
value that is in this range (see section 5.4.2).  A value of 0 indicates
an infinite lease, i.e., one that does not expire.

5.5.8 notify-lease-time-default (integer(0:MAX))

This REQUIRED Printer attribute specifies the value of the lease time
that the Printer object has been configured to assume if the client does
not supply a "notify-lease-time-requested" operation attribute in the
Create-Printer-Subscription or Renew-Printer-Subscription requests.

5.5.9 persistent-jobs-supported (boolean)

This OPTIONAL Printer attribute indicates whether or not the Printer
supports persistent Jobs, i.e., Jobs object that are preserved across
power cycles.  If Jobs are persistent, then Per-Job Subscriptions MUST
also be persistent, since they are part of the Job object.  It is
RECOMMENDED that Jobs (and Per-Job Subscriptions) be persistent.

5.5.10persistent-subscriptions-supported (boolean)

This OPTIONAL Printer attribute indicates whether or not the Printer
supports persistent Per-Printer Subscriptions, i.e., Subscription
objects that are preserved across power cycles.  When this value is
'true' the implementation MAY support some that are persistent and some
that are not.  If the value is 'false' or the attribute is not
supported, Per-Printer Subscriptions MUST NOT be persistent.  It is
RECOMMENDED that Per-Printer subscriptions be persistent.

5.5.11printer-state-change-time (integer(1:MAX))

This OPTIONAL Printer attribute records the time, i.e., copy of the
Printer's "printer-up-time" attribute, that the Printer's "printer-
state" attribute was last changed.  On power-up, the Printer populates
the "printer-state-change-time" from its "printer-up-time" attribute, so
that it always has a value.

5.5.12printer-state-change-date-time (dateTime)

This OPTIONAL Printer attribute records the date and time, i.e., copy of
the Printer's "printer-current-time" attribute, that the Printer's
"printer-state" attribute was last changed.  On power-up, the Printer
populates the "printer-state-change-date-time" from its "printer-
current-time" attribute, so that it always has a value.




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6  Notification Content


This section defines the Notification content that is sent to a
Notification Recipient when an event occurs.  The Notification MAY be
sent by the IPP Printer or a third party Notification Service (see
section 2.3).  There are two notification content types: Machine
Consumable and Human Consumable.  For most notification delivery methods
both content types are defined.  Some of the notification delivery
methods are defined to support only one content type.  A Printer MUST
support all content types defined for a notification delivery method, if
it supports that notification delivery method.


6.1 Notification content MIME media type formats

This section defines the Notification content that the Notification
Source sends asynchronously to each Notification Recipient based on the
subscription information stored with the subscription.

Notifications are generated using the following content formats:

     'application/ipp' - Machine Consumable notification content using
       the 'application/ipp' MIME media type [ipp-mod] using the Get-
       Job-Attributes response encoding for job events and Get-Printer-
       Attributes for printer events.  The attributes listed in
       sections 6.2 and 6.3 are sent in an notification for Job events.
       The attributes listed in sections 6.2 and 6.4 are sent in an
       notification for Printer events.  For any string in any
       notification, the charset and natural language rules that apply
       to all IPP operations apply to the notification strings as well,
       since they are represented as operation responses.  The
       Unsupported Attributes Group in the response is not sent.  If
       the values of any of the attributes sent in an notification
       content are not known, the value sent in the report content is
       the out-of-band 'unknown' value, rather than omitting the
       attribute (see the beginning of [ipp-mod] section 4.1).

       An implementation MAY extend the contents of the Machine
       Consumable notification by adding additional attributes.

     'text/plain; charset=utf-8' -  Human Consumable notification
       content type [RFC2046].  The text message SHOULD include
       information about the attributes in sections 6.2 and 6.3 for job
       events or in sections 6.2 and 6.4 for printer events.  This
       information is localized according to the information about
       natural language and charset in the subscription.

       An implementation MAY extend the contents of a Human Consumable
       notification by adding additional information.


6.2 Notification content attributes common to Job and Printer events

This section lists the parameters and attributes that are included in
both Job and Printer event Notifications.  Some events do not include
all of these attributes as shown in Table 6.  Each notification content
contains a single Job or Printer event, whether that event was
subscribed using the Job Submission Subscription mechanism or the Per-


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Printer subscription mechanism.  If either kind of subscription
subscribed to both Job and Printer events, then they will be sent as
separate Job notification content and Printer notification contents to
the same Notification Recipient.

    Table 6 - Common Job and Printer Notification content attributes

                                     Reference          Events

Attributes                                       'job-      all
                                                 progress'  others

                                                 R          R
1. version-number (integer         mod 3.1.1
  (0:32767))

                                                 R          R
2. status-code (integer            mod 3.1.1
  (0:32767))

3. request-id (integer (0:MAX))    5.3.7 & mod   R          R
                                   3.1.1

4. attributes-charset (charset)    5.3.5 & mod   R          R
                                   3.1.4

5. attributes-natural-language     5.3.6 & mod   R          R
  (naturalLanguage)               3.1.4

                                                 R          R
6. printer-uri (uri)               5.4.3

                                                             R
7. printer-name (name(127))        mod 4.4.4

                                                 R          R**
8. job-id (integer(1:MAX))         mod 4.3.2

                                                             R**
9. job-name (name(MAX))            mod 4.3.5

10.trigger-event (type2 keyword)   5.3.2         R          R

11.trigger-time                                  R          R
  (integer(MIN:MAX))

12.trigger-date-time (dateTime)                              O

13.subscription-id                 5.4.1         R          R
  (integer(1:MAX))

                                                             R
14.subscriber-user-name            5.4.4
  (name(MAX))

15.subscriber-user-data            5.3.4                     R
  (octetString(63))

Attribute Notes:

"status-code" - a value of 600 for a Job event and 601 for a Printer
     event.

"request-id" - the sequence number for this subscription, starting at 1
     for each subscription.

"attributes-charset" - the value comes from the "notify-attributes-
     charset" in the "job-notify" Per-Job Subscription and the "notify-
     attributes-charset" in the Per-Printer Subscription object.




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"attributes-natural-language" - the value comes from the "notify-
     attributes-natural-language" in the "job-notify" Per-Job
     Subscription and the "notify-attributes-natural-language" in the
     Per-Printer Subscription object.

"printer-uri" - the value comes from the "job-printer-uri" Job attribute
     for Per-Job subscriptions.

**"job-id" and "job-name" - included in Printer event Notifications only
     for Per-Job subscriptions.

"trigger-event" - the event that caused this Notification to be
     delivered.

"trigger-time" - the "printer-up-time" value when the event occurred.

"trigger-date-time" - the "printer-current-time" value when the event
     occurred - OPTIONAL to support.

"job-name" - SNMP delivery method can truncate to less than 255 octets,
     since the Notification needs to fit into 484 octets or so on some
     transports that SNMP is defined for.

"subscription-id" - for Per-Job subscriptions, the value is the index of
     the "job-notify" collection value, starting with 1 for the first
     collection value.

"subscriber-user-name" - comes from "requesting-user-name" Job attribute
     for Per-Job subscriptions.  SNMP delivery method can truncate to
     less than 255 octets, since the Notification needs to fit into 484
     octets or so on some transports that SNMP is defined for.

"subscriber-user-data" - opaque user data that may identify either the
     Subscriber and/or the ultimate Notification Recipient.


6.3 Additional Notification content attributes for Job events only

This section lists the additional attributes that are included only in
Job event Notifications.  Some events do not include all of these
attributes as shown in Table 7.

Table 7 - Additional Notification content attributes for Job events only

                                                          Events

Attributes                              Reference 'job-  'job-   all
                                                   progre complet othe
                                                   ss'    ed'     rs

16.job-state (type1 enum)               mod 4.3.7         R       R

17.job-state-reasons (1setOf type2      mod 4.3.8         R       R
  keyword)

18.job-k-octets-processed               mod       O      O



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                                                          Events

Attributes                              Reference 'job-  'job-   all
                                                   progre complet othe
                                                   ss'    ed'     rs

  (integer(0:MAX))                      4.3.18.1

19.job-impressions-completed            mod       O      O
  (integer(0:MAX))                      4.3.18.2

20.job-media-sheets-completed           mod       O      O
  (integer(0:MAX))                      4.3.18.3

21.job-collation-type (type2 enum)      [ipp-     R
                                        prog]

22.sheet-completed-copy-number          [ipp-     R
  (integer(-2:MAX))                     prog]

23.sheet-completed-document-            [ipp-     R
  number(integer(-2:MAX))               prog]

24.impressions-interpreted (integer(-   [ipp-     R
  2:MAX))                               prog]

25.impressions-completed-current-copy   [ipp-     R
  (integer(-2:MAX))                     prog]


6.4 Additional Notification content attributes for Printer events only

Table 8 lists the additional attributes that are included only in
Printer event Notifications.

Table 8 - Additional Notification content attributes for Printer events
                                  only

                                                               Events

Attributes                                       Reference  all printer
                                                             events

26.printer-state (type1 enum)                   mod 4.4.11 R

27.printer-state-reasons (1setOf type2 keyword) mod 4.4.12 R

28.printer-is-accepting-jobs (boolean)          mod 4.4.23 R



7  Operations for Per-Job Subscriptions


This section defines the REQUIRED operation requests and responses that
are related to Per-Job subscriptions.   Section 8 defines the REQUIRED
operation requests and responses associated with the REQUIRED Per-
Printer subscription and its Subscription object.








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7.1 Job Creation Operations (Create-Job, Print-Job, Print-URI) and
    Validate-Job

The usual method for a client to associate one subscription with a Job
is to specify the subscription when the job is created.  For a Per-Job
Subscription, the client supplies the "job-notify (1setOf collection)"
operation attribute with the member attributes listed in Table 9 with
any of the job creation operations (Create-Job, Print-Job, Print-URI),
plus Validate-Job (which doesn't create a job or subscription).  If the
client does not supply the "job-notify" attribute in the create
operation, there is no subscription made (either implicitly or
explicitly).

If a Printer does not support this notification specification, then it
MUST ignore the "job-notify" operation attribute and return it in the
response indicated as an attribute that is not supported.  See [ipp-mod]
section 3.1.7 for details on returning Unsupported Attributes.

  Table 9 - Member attributes of the "job-notify" collection operation
                               attribute

Member attribute of "job-notify"        Reference  REQUIRED  Printer
collection                                          in        support
                                                    request

notify-recipient (uri)                  5.3.1      yes       REQUIRED

notify-events (1setOf type2 keyword)    5.3.2      no        REQUIRED

notify-content-type (mimeMediaType)     5.3.3      no        REQUIRED

subscriber-user-data (octetString(63))  5.3.4      no        REQUIRED

notify-attributes-charset (charset)     5.3.5      no        OPTIONAL

notify-attributes-natural-language      5.3.6      no        OPTIONAL
(naturalLanguage)

See the referenced sections for a definition of these operation
attributes, since they are copied to the Job object as the Job
Description attributes described in section 5.3.

The following rules apply to Per-Job subscriptions:

1.Any subscription can contain job events, printer events, or both.

2.The Job Submission Subscription is only valid while the job is "not-
  completed".  The job is "not-completed" while it is in the 'pending',
  'pending-held', 'processing', and 'processing-stopped' states.  The
  job changes from being "not-completed" to "retained" when it is done
  processing and enters any of the 'completed', 'canceled', or
  'aborted' states.  The job becomes "not-completed" again when it is
  restarted using the Restart-Job operation (see [ipp-mod]).

3.Since no job is created for the Validate-Job operation, the only
  purpose of supplying the subscription operation attributes in the
  Validate-Job operation is to validate that the values are supported;
  the Printer object does not establish a notification subscription as
  a result of the Validate-Job operation.




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4.Since a Job Submission Subscription is included within a job
  submission operation, any interest in job events is limited to "this
  job" only (the Job object created because of this job creation
  operation).  There is no mechanism to subscribe to events for all
  jobs or specifically some job other than this job in a create
  operation.  But see the Create-Printer-Subscription operation
  (section 8.1) for an explicit operation to subscribe for job and/or
  printer events independently of any particular job submission.

5.Event reporting only occurs when a notification recipient has
  specified a subscription to any event(s).

6.The notification implementation MAY allow an administrator to
  configure a policy on what events may be dropped.

7.If the OPTIONAL "notify-attributes-charset" attribute is not
  supported or the supplied value is not supported, the IPP Printer
  MUST return the attribute in the Unsupported Attributes Group but
  still accept the operation, as with all Job create operations.  In
  this case, the Printer MUST use the natural language supplied in the
  "attributes-charset" Job creation operation attribute, if that
  natural language value is supported by the Printer, else the Printer
  object MUST use the Printer's "charset-configured" value.  See the
  Print-Job operation in [ipp-mod].

8.If the OPTIONAL "notify-attributes-natural-language" attribute is not
  supported or the supplied value is not supported, the IPP Printer
  MUST return the attribute in the Unsupported Attributes Group but
  still accept the operation, as with all Job create operations.  In
  this case, the Printer MUST use the natural language supplied in the
  "attributes-natural-language" Job creation operation attribute, if
  that natural language value is supported by the Printer, else the
  Printer object MUST use the Printer's "natural-language-configured"
  value.  See the Print-Job operation in [ipp-mod].


7.2 Get-Printer-Attributes operation

The REQUIRED (by [ipp-mod]) Get-Printer-Attributes can be used to
request the additional Printer Description attributes that indicate the
notification supported.  See section 5.5.


7.3 Get-Job-Attributes operation

The REQUIRED (by [ipp-mod]) Get-Job-Attributes can be used to request
the additional Job Description attributes that relate to notification.
See section 5.5.











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7.4 Set-Job-Attributes operation

The OPTIONAL Set-Job-Attributes operation (see [ipp-set2]) allows a
client to change the Job attributes of the Job's Per-Job subscription,
including to add them in the first place if they had not been supplied
in the Job creation operation and to remove them from the Job object.
This operation replaces all the collection values of the supplied "job-
notify (1setOf collection) notification attribute.

In order to cancel all Per-Job subscriptions, the client supplies the
"job-notify" attribute with an out-of-band 'none' value (see [ipp-
coll]).

Request:
   Group 1: Operation Attributes                   Printer
                                                    support
        "attributes-charset" (charset)             R
        "attributes-natural-language"              R
        (naturalLanguage)
        "printer-uri" (uri)                        R
        "requesting-user-name" (name(MAX))         RECOMMENDED
        "job-notify" (1setOf collection)           R
Response:
   Group 1: Operation Attributes                   Printer
                                                    support
        "status-code" (type2 enum)                 R
        "attributes-charset" (charset)             R
        "attributes-natural-language"              R
        (naturalLanguage)
        ["status-message" (text(255))]             O
        ["detailed-status-message" (text(MAX))]    O
   Group 2: Unsupported Attributes                 R

The "job-notify" operation attribute is copied to the "job-notify" Job
Description attribute.  See section 5.1 for a definition of the "job-
notify" Job Description attribute.


8  Per-Printer Subscriptions and the Subscription object


This section lists the REQUIRED Per-Printer Subscriptions operation
requests and responses and the Subscription object that MUST be
supported.

ISSUE 3 - Are these abbreviated operation definitions ok for
understandability and conformance, or should we use the more verbose
definition style of the [ipp-mod]?


8.1 Create-Printer-Subscription operation

The REQUIRED Create-Printer-Subscription operation creates a Per-Printer
subscription by creating a Per-Printer Subscription object which is
added to the Printer object.  The client can specify one or more job
and/or printer events to be delivered as notifications to one
Notification Recipient.  The job events are for any job submitted to the
Printer.  The printer events are any events generated by that Printer.


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The Printer returns a subscription id and the length of time for which
it has granted a lease for the subscription.  The client must renew the
subscription using the Renew-Printer-Subscription operation (see section
8.4) before the lease runs out in order to maintain the subscription.  A
client can unsubscribe using the Cancel-Printer-Subscription operation
(section 8.5) and the subscription id.

Two Create-Printer-Subscription operations with the same events and same
Notification Recipient MUST be kept as distinct subscriptions and be
assigned distinct subscription ids.  A Printer MUST allow such duplicate
subscriptions such that Cancel-Printer-Subscription doesn't unsubscribe
both subscriptions and MUST send the Notifications twice to the
Notification Recipient, since the "request-id" is supposed to count
monotonically for each subscription.

If the Printer has a bounded set of concurrent subscriptions (for the
specified events or any events), the printer rejects the operation and
returns the 'server-error-too-many-subscriptions' status code.  The
client SHOULD try again later.

Access Rights: The authenticated user (see [IPP-MOD] section 8.3)
performing this operation MUST have operator or administrator access
rights for the Printer object (see [IPP-MOD] sections 1 and 8.5).
Otherwise the IPP object MUST reject the operation and return: client-
error-forbidden, client-error-not-authenticated, and client-error-not-
authorized as appropriate.






























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Request:
   Group 1: Operation Attributes                   Printer
                                                    support
        "attributes-charset" (charset)             R
        "attributes-natural-language"              R
        (naturalLanguage)
        "printer-uri" (uri)                        R
        ["requesting-user-name" (name(MAX))]       RECOMMENDED
        ["notify-recipient" (uri)]                 R
        ["notify-events" (1setOf type2 keyword)]   R
        ["notify-content-type" (mimeMediaType)]    R
        ["subscriber-user-data" (octetString(63))] R
        ["notify-attributes-charset" (charset)]    O
        ["notify-attributes-natural-language"      O
        (naturalLanguage)]
        ["notify-lease-time-requested"             R
        (integer(0:MAX))]
        ["notify-persistence-requested" (boolean)] O
Response:
   Group 1: Operation Attributes                   Printer
                                                    Support
         "status-code" (type2 enum)                R
         "attributes-charset" (charset)            R
         "attributes-natural-language"             R
        (naturalLanguage)
        ["status-message" (text(255))]             O
        ["detailed-status-message" (text(MAX))]    O
         "subscription-id"  (integer(1:MAX))       R
         "notify-lease-expiration-time"            R
        (integer(0:MAX))
         "notify-lease-time-granted"               R
        (integer(0:MAX))
         "notify-persistence-granted" (boolean)    R
   Group 2: Unsupported Attributes                 R

Attribute Notes:

"notify-recipient" (uri) - the client MUST supply this attribute in
     order to have a subscription.

"notify-lease-time-requested" (integer(0:MAX) - the number of seconds
     requested for the Per-Printer subscription lease.  A value of 0
     indicates a request that the Per-Printer Subscription lease never
     expire.  Supplying a 0 value MAY require authentication in order to
     be used, if 0 is supported at all.
     If the client does not supply this attribute, the Printer uses its
     "notify-lease-time-default" value (see section 5.5.8).

"notify-persistence-requested" (boolean) - whether or not the Per-
     Printer Subscription is to be persistent, i.e., saved across power
     cycles.  Note: Persistent trap registrations is a client option in
     SNMPv3 [RFC2573].
     "notify-lease-expiration-time" (integer(0:MAX)) - The Printer


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     object MUST return this attribute which is the time in the future
     at which the subscription lease will expire, i.e., the "printer-up-
     time" value (in time ticks - see [ipp-mod] section 4.4.29) at which
     the Printer will delete the Subscription.  A value of 0 indicates
     that the lease subscription will never expire.

"notify-lease-time-granted" - The Printer object MUST return this
     attribute which is the number of seconds of time actually granted.
     The value of "notify-lease-time-granted" may be less than the
     requester requested in the "notify-lease-time-requested" if it was
     greater than the MAX supported or more than the requester requested
     if it was less than the MIN supported, as indicated in the
     Printer's "notify-lease-time-supported" (rangeOfInteger(0:MAX))
     attribute.

"notify-persistence-granted" - whether or not this Per-Printer
     Subscription object instance is persistent.  This attribute MUST be
     returned whether "notify-persistence-requested" is supported or
     not, so that the client knows which.


8.2 Get-Printer-Subscription-Attributes operation

The REQUIRED Get-Printer-Subscription-Attributes returns the requested
attributes of the identified Per-Printer Subscription object.  See
sections 5.3 and 5.4.

Request:
   Group 1: Operation Attributes                        Printer
                                                         support
         "attributes-charset" (charset)                 R
         "attributes-natural-language"                  R
        (naturalLanguage)
         "printer-uri" (uri)                            R
        ["requesting-user-name" (name(MAX))]            RECOMMENDED
         "subscription-id"  (integer(1:MAX))            R
        ["requested-attributes" (1setOf type2 keyword)] R
Response:
   Group 1: Operation Attributes                        Printer
                                                         support
        "status-code" (type2 enum)                      R
        "attributes-charset" (charset)                  R
        "attributes-natural-language" (naturalLanguage) R
        ["status-message" (text(255))]                  O
        ["detailed-status-message (text(MAX))]          O
   Group 2: Unsupported Attributes                      R
   Group 3: <the requested Subscription object          R
   attributes>

This operation is similar to the Get-Printer-Attributes operation.  If
the client omits the "requested-attributes" operation attribute, the
Printer MUST respond as if the client had supplied the 'all' value,
i.e., return all of the attributes supported for the Subscription
object.



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8.3 Get-Printer-Subscriptions operation

The REQUIRED Get-Printer-Subscriptions operation returns Per-Printer
subscriptions, i.e., Subscription objects.

Request:
   Group 1: Operation Attributes                        Printer
                                                         support
        "attributes-charset" (charset)                  R
        "attributes-natural-language" (naturalLanguage) R
        "printer-uri" (uri)                             R
        ["requesting-user-name" (name(MAX))]            RECOMMENDED
        ["limit" (integer(1:MAX))]                      R
        ["requested-attributes" (1setOf type2 keyword)] R
        ["my-subscriptions" (boolean)]                  R
Response:
   Group 1: Operation Attributes                        Printer
                                                         support
        "status-code" (type2 enum)                      R
        "attributes-charset" (charset)                  R
        "attributes-natural-language" (naturalLanguage) R
        ["status-message" (text)]                       O
        ["detailed-status-message" (text(MAX))]         O
   Group 2: Unsupported Attributes                      R
   Group 3 to N:<the requested Subscription Attributes  R
   for each Subscription object in a separate group>


Notes:  This operation is similar to the Get-Jobs operation (see [ipp-
mod]).  If the client wants any attributes returned, including the
"subscription-id", it must include the attribute keyword name in the
"requested-attributes" operation attribute.  If the "requested-
attributes operation attribute is omitted, the Printer MUST respond as
if the client supplied the value: 'subscription-id'.  If the client
supplies the "my-subscriptions" with a 'false' value or omits it, the
Printer returns all subscriptions, subject to the security policy in
force.


8.4 Renew-Printer-Subscription operation

The REQUIRED Renew-Printer-Subscription operation permits a client to
request the IPP Printer to extend the lease on a Per-Printer
Subscription object instance.

Access Rights: The authenticated user (see [IPP-MOD] section 8.3)
performing this operation MUST either be the owner of the Subscription
object or have operator or administrator access rights for the Printer
object (see [IPP-MOD] sections 1 and 8.5).  Otherwise the IPP object
MUST reject the operation and return: client-error-forbidden, client-
error-not-authenticated, and client-error-not-authorized as appropriate.








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Request:
   Group 1: Operation Attributes                         Printer
                                                          support
        "attributes-charset" (charset)                   R
        "attributes-natural-language" (naturalLanguage)  R
        "printer-uri" (uri)                              R
        ["requesting-user-name" (name(MAX))]             RECOMMENDED
        "subscription-id"  (integer(1:MAX))              R
        ["notify-lease-time-requested"                   R
        (integer(0:MAX))]
Response:
   Group 1: Operation Attributes                         Printer
                                                          support
        "status-code" (type2 enum)                       R
        "attributes-charset" (charset)                   R
        "attributes-natural-language" (naturalLanguage)  R
        ["status-message" (text(255))]                   O
        ["detailed-status-message" (text(MAX))]          O
         "notify-lease-expiration-time"                  R
        (integer(0:MAX))
         "notify-lease-time-granted" (integer(0:MAX))    R
   Group 2: Unsupported Attributes                       R

Attribute Notes:

"notify-lease-time-requested" (integer(0:MAX) - the number of seconds
     requested for the Per-Printer subscription lease.  Same as Create-
     Printer-Subscriptions (see section 8.1).

"notify-lease-expiration-time" - the time in the future when the
     subscription will expire.  Same as for the Create-Printer-
     Subscription operation  (see section 7.1).

"notify-lease-time-granted" - the lease time (number of seconds)
     actually granted.  Same as for the Create-Printer-Subscription
     operation (see section 7.1).

Note:  There is no way to change any of the Subscription object
attributes, except the "notify-lease-expiration-time" attribute.  In
order to change other attributes, a client can create a new Subscription
object and then use the Cancel-Printer-Subscription operation to cancel
the old one (or do this in the other order, in case there is a limit on
the number of Subscription object instances, as long as a short window
with no Notifications is ok).

Note:  There is no need to renew a Per-Job Subscription, since it is
effectively the time that the Job is active (see section 7.1).


8.5 Cancel-Printer-Subscription operation

The REQUIRED Cancel-Printer-Subscription operation allows a client to
remove a Per-Printer Subscription object from the Printer.  No more
Notifications are delivered for that Subscription.  Once performed,
there is no way to use that Subscription in the future.  Subscription-


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ids should not be reused immediately, so that a stale reference
situation is not created.  Same as for Cancel-Job and job-ids.

Access Rights: The authenticated user (see [IPP-MOD] section 8.3)
performing this operation MUST either be the owner of the Subscription
object or have operator or administrator access rights for the Printer
object (see [IPP-MOD] sections 1 and 8.5).  Otherwise the IPP object
MUST reject the operation and return: client-error-forbidden, client-
error-not-authenticated, and client-error-not-authorized as appropriate.

Request:
   Group 1: Operation Attributes                          Printer
                                                          support
        "attributes-charset" (charset)                    R
        "attributes-natural-language" (naturalLanguage)   R
        "printer-uri" (uri)                               R
        ["requesting-user-name" (name(MAX))]              RECOMMENDED
        "subscription-id" (integer(1:MAX))                R
Response:
   Group 1: Operation Attributes                          Printer
                                                          support
        "status-code" (type2 enum)                        R
        "attributes-charset" (charset)                    R
        "attributes-natural-language" (naturalLanguage)   R
        ["status-message" (text(255))]                    O
        ["detailed-status-message" (text(MAX))]           O
   Group 2: Unsupported Attributes                        R



9  Comparison of Per-Job Submission Subscriptions versus Per-Printer
   Subscriptions


Per-Job and Per-Printer subscriptions are quite similar.  However, there
are some semantic differences between Per-Job subscriptions and Per-
Printer subscriptions.  A Per-Job Submission Subscription is established
by the client when submitting a job.  A Per-Printer  Subscription is
established between a client and a Printer using the new Create-Printer-
Subscription operation.  Some specific differences are:

1.Either type of subscription can subscribe to Job events, Printer
  events, or both.

2.For Per-Job Subscriptions, the subscription is only valid while the
  job is "not-complete" (see sections 6.2 and 6.3).

3.For the Per-Printer Subscriptions, the subscription is valid until it
  is explicitly canceled with a Cancel-Printer-Subscription operation
  or the time (in seconds) that the Printer returned in the "notify-
  lease-time-granted" operation attribute expires, whichever occurs
  first.

4.Job Events in a Per-Job Subscription apply only to "one job" (the Job
  created by the job creation  operation).




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5.Job Events in a Per-Printer-Subscription apply to ALL jobs contained
  in the IPP Printer object.

6.Printer Events in both kinds of subscriptions apply no matter which
  job is being processed, if any.



10 Conformance Requirements


This section further enhances the Conformance Requirements detailed in
[IPP-MOD] section 5.  Extensions made to the events herein must be made
such that new events or event attributes are backward compatible to
clients who implemented early versions of this notification
specification.

It is OPTIONAL to implement this Event Notification specification.  If
implemented, IPP objects MUST support all of the REQUIRED object
attributes as defined in this document in the indicated sections.

If IPP Notification is implemented, the operations described in this
document must be supported as described in Table 10:

           Table 10 - Conformance Requirements for Operations

    Attribute                                              Conformance
                                                           requirements
    "job-notify" in Job Creation operations (section 7.1)  REQUIRED
    Set-Job-Attributes (see section 7.4)                   OPTIONAL
    Create-Printer-Subscription (section 8.1)              REQUIRED
    Get-Printer-Subscription-Attributes (section 8.2)      REQUIRED
    Get-Printer-Subscriptions (section 8.3)                REQUIRED
    Renew-Printer-Subscription (section 8.4)               REQUIRED
    Cancel-Printer-Subscription (section 8.5)              REQUIRED


11 IANA Considerations


IANA will be called on to register URL schemes for notification delivery
for use in the "notification-recipient" attribute, using the same
procedures outlined in [ipp-mod].


12 Internationalization Considerations


This IPP notification specification continues the internationalization
of [ipp-mod] for attributes containing text strings and names.  A
subscribing client can specify a different natural language and charset
for each Notification content delivered to a Notification Recipient.

The Human Consumable Notification content is a 'text/plain; charset=utf-
8' by default where the Notification Sender has localized the text
message as requested by the subscriber for the intended Notification
Recipient.




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13 Security Considerations


By far the biggest security concern is the abuse of notification:
sending unwanted notifications to third parties (i.e., spam).  The
problem is made worse by notification addresses that may be
redistributed to multiple parties (e.g. mailing lists).  There exist
scenarios where third party notification is required (see Scenario #2
and #3 in [ipp-not-req]).  The fully secure solution would require
active agreement of all recipients before sending out anything.
However, requirement #9 in [ipp-req] (.There is no requirement for IPP
Printer receiving the print request to validate the identity of an event
recipient.) argues against this.  Certain systems may decide to disallow
third party notifications (a traditional fax model).

Clients submitting notification requests to the IPP Printer has the same
security issues as submitting an IPP/1.1 print job request.  The same
mechanisms used by IPP/1.1 can therefore be used by the client
notification submission.  Operations that require authentication can use
the HTTP authentication.  Operations that require privacy can use the
HTTP/TLS privacy.

The notification access control model should be similar to the IPP
access control model for Jobs.  Creating a Per-Printer Notification
Subscription object is associated with a user.  Only the creator or an
operator can cancel the subscription.  The system may limit the listing
of items to only those items owned by the user.  Some subscriptions
(e.g. those that have a lifetime longer than a job) can be done only by
privileged users (users having operator and/or administrator access
rights), if that is the authorization policy.

The standard security concerns (delivery to the right user, privacy of
content, tamper proof content) apply to the notification delivery.  IPP
should use the security mechanism of the delivery method used.  Some
delivery mechanisms are more secure than others.  Therefore, sensitive
notifications should use the delivery method that has the strongest
security.


14 Status Codes


The following status codes are defined as extensions for notification:


14.1client-error-uri-notification-scheme-not-supported (0x04??)

The scheme of the client-supplied URI in a "notify-recipient" operation
attribute in a Create-Printer-Subscription operation is not supported.
See [ipp-mod] section 3.1.7.

Note:  There is no corresponding Per-Job subscription error, since the
Printer object MUST ignore any errors in the "job-notify" operation
attribute and perform the Job Creation operation (see section  5.1),
since the job can still be printed.

ISSUE 4 - The client-error-uri-scheme-not-supported is already an
IPP/1.1 status code and section 3.1.6.1 indicates that the "document-



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uri" attribute NEED NOT be returned in the Unsupported Attributes group,
otherwise, we could use that error code and REQUIRE that offending "xxx-
uri" attribute(s) to be returned.


14.2server-error-too-many-subscriptions (0x04??)

The bounded set of concurrent Per-Printer subscriptions supported by the
Printer object would be exceeded if this request were accepted.

Note:  There is no corresponding Per-Job subscription error, since the
Printer object MUST ignore any errors in the "job-notify" operation
attribute and perform the Job Creation operation (see section  5.1),
since the job can still be printed.


14.3server-error-too-many-events (0x04??)

The client supplied more events in the "notify-events" operation
attribute in a Create-Printer-Subscription that the Printer supports, as
indicated in its "max-events-supported" attribute (see section 5.5.4).

Note:  There is no corresponding Per-Job subscription error, since the
Printer object MUST ignore any errors in the "job-notify" operation
attribute and perform the Job Creation operation (see section  5.1),
since the job can still be printed.

ISSUE 5 - Should the entire "job-notify" operation attribute be ignored,
if one of its member attributes has a problem, or should just that
member attribute be ignored?  If the latter, then is just the member
attribute returned in the Unsupported Attributes group?


15 References

[ipp-coll]
     deBry, R., , Hastings, T., Herriot, R., "Internet Printing
     Protocol/1.0 & 1.1: collection attribute syntax", <draft-ietf-ipp-
     collection.doc>, work in progress, August 22, 1999.

[ipp-mod]
     deBry, R., , Hastings, T., Herriot, R., Isaacson, S., Powell, P.,
     "Internet Printing Protocol/1.1: Model and Semantics", < draft-
     ietf-ipp-model-v11-04.txt>, work in progress, June 23, 1999.

[ipp-not-hist]
     deBry, R., Lewis, H., Hastings, T., "Internet Printing
     Protocol/1.1: Requirements for IPP Notifications", <draft-ietf-ipp-
     not-change-history-00.doc>, work in progress, August 22, 1999.

[ipp-not-req]
     deBry, R., Lewis, H., Hastings, T., "Internet Printing
     Protocol/1.1: Requirements for IPP Notifications", <draft-ietf-ipp-
     not-03.txt>, work in progress, August 11, 1999.





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[ipp-set2]
     Kugler, C., , Hastings, T., "Internet Printing Protocol/1.0 & 1.1:
     Additional Operations, Set 2", <draft-ietf-ipp-set2.txt>, work in
     progress, August 22, 1999.

[ipp-prog]
     Hastings, T., Bergman, R., Lewis, H., "Proposed Job Progress
          Attributes for IPP", <draft-ietf-ipp-prog.txt>  work in
          progress, May 18, 1999.

[RFC2046]
     Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types.
     N. Freed & N. Borenstein. November 1996. (Obsoletes RFC1521,
     RFC1522, RFC1590), RFC 2046.

[RFC2119]
     S. Bradner, "Key words for use in RFCs to Indicate Requirement
     Levels", RFC 2119 , March 1997

[RFC2566]

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


16 Author's Addresses

   Scott A. Isaacson (Editor)
   Novell, Inc.
   122 E 1700 S
   Provo, UT  84606

   Phone: 801-861-7366
   Fax: 801-861-2517
   e-mail: sisaacson@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

   Roger deBry
   Utah Valley State College
   Orem, UT 84058

   Phone: (801) 222-8000
   EMail: debryro@uvsc.edu

   Jay Martin


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   e-mail: jkm@underscore.com

   Michael Shepherd
   Xerox Corporation
   800 Phillips Road  MS 128-51E
   Webster, NY  14450

   Phone: 716-422-2338
   Fax: 716-265-8871
   e-mail: mshepherd@crt.xerox.com

   Ron Bergman (Editor)
   Dataproducts Corp.
   1757 Tapo Canyon Road
   Simi Valley, CA 93063-3394

   Phone: 805-578-4421
   Fax:  805-578-4001
   Email: rbergman@dpc.com


A.   Appendix - Summary of Notification Attribute Usage

This appendix summarizes the usage of Notification attributes in the Job
operation attribute collection, Job object, Subscription object,
Notification content, Job operations, and Subscriptions operations.

ISSUE 6 - Should this appendix be kept in the spec or moved to the
Implementer's Guide?




17 Appendix C: Full Copyright Statement

Copyright (C) The Internet Society (1998,1999). 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.

This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK



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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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