Internet Printing Protocol WG Robert Herriot (editor)
INTERNET-DRAFT Xerox Corp.
<draft-ietf-ipp-notify-get-04.txt> Carl Kugler
Updates: RFC 2911 Harry Lewis
[Target category: standards track] IBM, Corp.
Expires: January 17, 2002 July 17, 2001
Internet Printing Protocol (IPP):
The 'ippget' Delivery Method for Event Notifications
Copyright (C) The Internet Society (2001). All Rights Reserved.
Status of this Memo:
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of [rfc2026]. Internet-Drafts are
working documents of the Internet Engineering Task Force (IETF), its
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
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Abstract
This document describes an extension to the Internet Printing
Protocol/1.0 (IPP) [RFC2566, RFC2565] and IPP/1.1 [RFC2911, RFC2910].
This document specifies the 'ippget' Delivery Method for use with the
"IPP Event Notifications and Subscriptions" specification [ipp-ntfy].
When IPP Notification [ipp-ntfy] is supported, the Delivery Method
defined in this document is one of the RECOMMENDED Delivery Methods
for Printers to support.
The 'ippget' Delivery Method is a 'pull' Delivery Method with aspects
of a 'push' method as well. That is, when an Event occurs, the
Printer saves the Event Notification for a period of time called the
Event Notification Lease Time. The Notification Recipient fetches
(pulls) Event Notifications using the Get-Notifications operation.
If the Notification Recipient has selected the option to wait for
additional Event Notifications, the Printer continues to return
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(similar to push) Event Notifications to the Notification Recipient
as Get-Notification responses as Events occur. This push aspect is
not a true 'push', since the Printer does not open the connect, but
rather continues to return responses as Events occur using the
connection originated by the Notification Recipient.
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Table of Contents
1 Introduction.....................................................5
2 Terminology......................................................5
3 Model and Operation..............................................6
4 General Information..............................................8
5 Get-Notifications operation......................................9
5.1 Get-Notifications Request.....................................11
5.2 Get-Notifications Response....................................13
6 Subscription Template Attributes................................18
6.1 Subscription Template Attribute Conformance...................18
6.2 Additional Information about Subscription Template Attributes.18
6.2.1 notify-recipient-uri (uri)..................................18
6.3 Subscription Description Attribute Conformance................19
7 Attributes only in Event Notifications..........................19
7.1 "notify-get-interval" (integer(0:MAX))........................19
8 Additional Printer Description Attributes.......................20
8.1 ippget-event-time-to-live (integer(0:MAX))....................20
9 New Values for Existing Printer Description Attributes..........21
9.1 notify-schemes-supported (1setOf uriScheme)...................21
9.2 operations-supported (1setOf type2 enum)......................21
10 New Status Codes...............................................21
10.1 redirection-other-site (0x0300)..............................21
11 The IPPGET URL Scheme..........................................22
11.1 The IPPGET URL Scheme Applicability and Intended Usage.......22
11.2 The IPPGET URL Scheme Associated Port........................22
11.3 The IPPGET URL Scheme Associated MIME Type...................22
11.4 The IPPGET URL Scheme Character Encoding.....................22
11.5 The IPPGET URL Scheme Syntax in ABNF.........................23
11.5.1 IPPGET URL Examples........................................24
11.5.2 IPPGET URL Comparisons.....................................24
12 Encoding and Transport.........................................25
13 Conformance Requirements.......................................26
13.1 Conformance for IPP Printers.................................26
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13.2 Conformance for IPP Clients..................................27
14 IANA Considerations............................................28
14.1 Operation Registrations......................................28
14.2 Additional attribute value registrations for existing attributes
28
14.2.1 Additional values for the "notify-schemes-supported" Printer
attribute..............................................28
14.2.2 Additional values for the "operations-supported" Printer
attribute..............................................29
14.3 Attribute Registrations......................................29
14.4 Status code Registrations....................................29
15 Internationalization Considerations............................30
16 Security Considerations........................................30
17 References.....................................................30
18 Authors' Addresses.............................................32
19 Description of Base IPP documents..............................33
20 Full Copyright Statement.......................................35
Table of Tables
Table 1 " Information about the Delivery Method....................8
Table 2 " Attributes in Event Notification Content................16
Table 3 " Additional Attributes in Event Notification Content for Job
Events........................................................17
Table 4 " Combinations of Events and Subscribed Events for "job-
impressions-completed"........................................17
Table 5 " Additional Attributes in Event Notification Content for
Printer Events................................................18
Table 6 " Operation-id assignments................................21
Table 7 " The "event-notification-attributes-tag" value...........26
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1 Introduction
The "IPP Event Notifications and Subscriptions" document [ipp-ntfy]
defines an OPTIONAL extension to Internet Printing Protocol/1.0 (IPP)
[RFC2566, RFC2565] and IPP/1.1 [RFC2911, RFC2910]. For a description
of the base IPP documents, see section 19. The [ipp-ntfy] extension
defines operations that a client can perform in order to create
Subscription Objects in a Printer and carry out other operations on
them. A Subscription Object represents a Subscription abstraction.
A client associates Subscription Objects with a particular Job by
performing the Create-Job-Subscriptions operation or by submitting a
Job with subscription information. A client associates Subscription
Objects with the Printer by performing a Create-Printer-Subscriptions
operation. Four other operations are defined for Subscription
Objects: Get-Subscriptions-Attributes, Get-Subscriptions, Renew-
Subscription, and Cancel-Subscription. The Subscription Object
specifies that when one of the specified Events occurs, the Printer
sends an asynchronous Event Notification to the specified
Notification Recipient via the specified Delivery Method (i.e.,
protocol).
The "IPP Event Notifications and Subscriptions" document [ipp-ntfy]
specifies that each Delivery Method is defined in another document.
This document is one such document, and it specifies the 'ippget'
delivery method. When IPP Notification [ipp-ntfy] is supported, the
Delivery Method defined in this document is one of the RECOMMENDED
Delivery Methods for Printers to support.
The 'ippget' Delivery Method is a 'pull' Delivery Method with aspects
of a 'push' method as well. That is, when an Event occurs, the
Printer saves the Event Notification for a period of time called the
Event Notification Lease Time. The Notification Recipient fetches
(pulls) the Event Notifications using the Get-Notifications
operation. This operation causes the Printer to return all Event
Notifications held for the Notification Recipient. If the
Notification Recipient has selected the option to wait for additional
Event Notifications, the Printer continues to return (similar to
push) Event Notifications to the Notification Recipient as Get-
Notification responses as Events occur. This push aspect is not a
true 'push', since the Printer does not open the connect, but rather
continues to return responses as Events occur using the connection
originated by the Notification Recipient.
2 Terminology
This section defines the following terms that are used throughout
this document:
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This document uses the same terminology as [RFC2911], such as
"client", "Printer", "Job", "attribute", "attribute value",
"keyword", "operation", "request", "response", and "support".
Capitalized terms, such as MUST, MUST NOT, REQUIRED, SHOULD, SHOULD
NOT, MAY, NEED NOT, and OPTIONAL, have special meaning relating to
conformance as defined in RFC 2119 [RFC2119] and [RFC2911] section
12.1. If an implementation supports the extension defined in this
document, then these terms apply; otherwise, they do not. These
terms define conformance to this document only; they do not affect
conformance to other documents, unless explicitly stated otherwise.
Event Notification Lease: The lease that is associated with an Event
Notification. When the lease expires, the Printer discards the
associated Event Notification.
Event Notification Lease Time: The expiration time assigned to a
lease that is associated with an Event Notification.
Event Notification Attributes Group: The attributes group in a
response that contains attributes that are part of an Event
Notification.
Event Wait Mode: The mode requested by a Notification Recipient
client in its Get-Notifications Request and granted by a Printer to
keep the connection open where the Printer sends subsequent Event
Notifications to the Notification Recipient as they occur as
additional Get-Notification Responses.
Other capitalized terms, such as Notification Recipient, Event
Notification, Compound Event Notification, Printer, etc., are
defined in [ipp-ntfy], have the same meanings, and are not reproduced
here.
3 Model and Operation
In a Subscription Creation Operation, when the value of the "notify-
recipient-uri" attribute has the scheme 'ippget', the client is
requesting that the Printer use the 'ippget' Delivery Method for the
Event Notifications associated with the new Subscription Object. The
client SHOULD choose a value for the address part of the "notify-
recipient-uri" attribute that uniquely identifies the Notification
Recipient.
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When an Event occurs, the Printer MUST generate an Event Notification
and MUST assign it the Event Notification Lease Time. The Printer
MUST hold an Event Notification for its assigned Event Notification
Lease Time. The Printer MUST assign the same Event Notification
Lease Time to each Event Notification.
When a Notification Recipient wants to receive Event Notifications,
it performs the Get-Notifications operation, which causes the Printer
to return all un-expired Event Notifications held for the
Notification Recipient. If the Notification Recipient has selected
the Event Wait Mode option to wait for additional Event
Notifications, the response to the Get-Notifications request
continues indefinitely as the Printer continues to send Event
Notifications in the response as Events occur. For the Get-
Notification operation, the Printer sends only those Event
Notifications that are generated from Subscription Objects whose
"notify-recipient-uri" attribute value equals the value of the
"notify-recipient-uri" Operation Attribute in the Get-Notifications
operation.
If a Notification Recipient performs the Get-Notifications operation
twice in quick succession, it will receive nearly the same Event
Notification both times because most of the Event Notifications are
those that the Printer saves for a few seconds after the Event
occurs. There are two possible differences. Some old Event
Notifications may not be present in the second response because their
Event Notification Leases have expired. Some new Event Notifications
may be present in the second response but not the first response,
because they occurred after the first response.
When the Notification Recipient requests Event Notifications for per-
Job Subscription Objects, the Notification Recipient typically
performs the Get-Notifications operation within a second of
performing the Subscription Creation operation. Because the Printer
is likely to save Event Notifications for several seconds, the
Notification Recipient is unlikely to miss any Event Notifications
that occur between the Subscription Creation and the Get-
Notifications operation.
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4 General Information
If a Printer supports this Delivery Method, the following are its
characteristics.
Table 1 " Information about the Delivery Method
Document Method Conformance Requirement Delivery Method
Realization
1. What is the URL scheme name for the ippget
Delivery Method?
2. Is the Delivery Method REQUIRED, RECOMMENDED
RECOMMENDED or OPTIONAL for an IPP
Printer to support?
3. What transport and delivery protocols IPP with one new
does the Printer use to deliver the Event operation.
Notification Content, i.e., what is the
entire network stack?
4. Can several Event Notifications be Yes.
combined into a Compound Event
Notification?
5. Is the Delivery Method initiated by the This Delivery Method
Notification Recipient (pull), or by the is a pull method
Printer (push)? with aspects of a
push method, though
the Printer does not
initiate the
connection.
6. Is the Event Notification content Machine Machine Consumable
Consumable or Human Consumable?
7. What section in this document answers the Section 5
following question? For a Machine
Consumable Event Notification, what is
the representation and encoding of values
defined in section 9.1 of [ipp-ntfy] and
the conformance requirements thereof? For
a Human Consumable Event Notification,
what is the representation and encoding
of pieces of information defined in
section 9.2 of [ipp-ntfy] and the
conformance requirements thereof?
8. What are the latency and reliability of Same as IPP and the
the transport and delivery protocol? underlying HTTP
transport
9. What are the security aspects of the Same as IPP and the
transport and delivery protocol, e.g., underlying HTTP
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how it is handled in firewalls? transport
10. What are the content length restrictions? None
11. What are the additional values or pieces None
of information that a Printer sends in an
Event Notification content and the
conformance requirements thereof?
12. What are the additional Subscription None
Template and/or Subscription Description
attributes and the conformance
requirements thereof?
13. What are the additional Printer None
Description attributes and the
conformance requirements thereof?
5 Get-Notifications operation
This operation is issued by a client acting in the role of a
Notification Recipient and causes the Printer to return all Event
Notifications held for the Notification Recipient.
A Printer MUST support this operation.
When a Printer performs this operation, it MUST return all and only
those Event Notifications:
1. Whose associated Subscription Object's "notify-subscription-id"
attribute equals the "notify-subscription-id" Operation
attribute if supplied AND
2. Whose associated Subscription Object's "notify-recipient-uri"
attribute equals the "notify-recipient-uri" Operation attribute
AND
3. Whose associated Subscription Object's "notify-recipient-uri"
attribute matches the scheme value of 'ippget' using the
matching rules in section 11.5.2 AND
4. Whose Event Notification Lease Time has not yet expired AND
5. Where the Notification Recipient is the owner of or has read-
access rights to the associated Subscription Object.
The Printer has the following options for responding to a Get-
Notifications Request:
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1. The Printer can reject the request and return the 'server-error-
busy' status code, if the Printer is too busy to accept this
operation at this time. In this case, the Printer MUST return
the "get-notify-interval" attribute to indicate when the client
should try again.
2. If the Notification Recipient did not request Event Wait Mode,
the Printer MUST respond to this operation immediately with
whatever Event Notifications it currently holds and return the
"notify-get-interval" attribute with number of seconds from now
at which the Notification Recipient MAY repeat the Get-
Notifications Request to get future Event Notifications.
3. If the Notification Recipient requested Event Wait Mode, the
Printer MUST respond to this operation immediately with whatever
Event Notifications it currently holds MUST continue to send
Event Notifications as they occur until all of the associated
Subscription Objects are cancelled. A Subscription Object is
cancelled either via the Cancel-Subscription operation or by the
Printer (e.g., the Subscription Object is cancelled when the
associated Job completes and is no longer in the Job Retention
or Job History phase - see the "ippget-event-time-to-live
(integer(0:MAX))" attribute discussion in section 8.1).
However, the Printer MAY decide to terminate Event Wait Mode at
any time, including in the first response. In this case the
Printer MUST return an additional Event Notification Attributes
Group that contains the single "notify-get-interval" attribute.
This attribute indicates that the Printer wishes to leave Event
Wait Mode and the number of seconds in the future that the
Notification Recipient SHOULD try the Get-Notifications
operation again. The Notification Recipient MUST accept this
response and MUST disconnect. If the Notification Recipient
does not disconnect, the Printer SHOULD do so.
If the Notification Recipient wishes to terminate the Get-
Notifications operation, it can close the connection. See section 12
for the encoding and transport rules for the Get-Notifications
Response for the Event Wait Mode.
The Printer MUST accept the request in any state (see [RFC2911]
"printer-state" and "printer-state-reasons" attributes) and MUST
remain in the same state with the same "printer-state-reasons"
values.
Access Rights: If the policy of the Printer is to allow all users to
access all Event Notifications, then the Printer MUST accept this
operation from any user. Otherwise, the authenticated user (see
[RFC2911] section 8.3) performing this operation MUST either be the
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owner of each Subscription Object identified by the "notify-
recipient-uri" Operation attribute (as determined during a
Subscription Creation Operation) or an operator or administrator of
the Printer (see [RFC2911] Sections 1 and 8.5). Otherwise, the IPP
object MUST reject the operation and return: 'client-error-
forbidden', 'client-error-not-authenticated', or 'client-error-not-
authorized' status code as appropriate.
5.1 Get-Notifications Request
The following groups of attributes are part of the Get-Notifications
Request:
Group 1: Operation Attributes
Natural Language and Character Set:
The "attributes-charset" and "attributes-natural-language"
attributes as described in [RFC2911] section 3.1.4.1.
Target:
The "printer-uri" (uri) operation attribute which is the target
for this operation as described in [RFC2911] section 3.1.5.
Requesting User Name:
The "requesting-user-name" (name(MAX)) attribute SHOULD be
supplied by the client as described in [RFC2911] section 8.3.
"notify-subscription-id" (integer(1:MAX)):
The client SHOULD supply this attribute, if known, and the
client is only monitoring a single Subscription object. The
Printer object MUST support this attribute. If supplied, but
no Subscription Object exists with this identifier, the Printer
MUST return the 'client-error-not-found' status code.
If supplied and the identified Subscription Object exists, the
Printer MUST check that the Subscription Object's "notify-
recipients-uri" attribute scheme is 'ippget' (case insensitive-
match - see section 11.5.2). If the scheme does not match
'ippget', the Printer MUST reject the request and return the
'client-error-uri-scheme-not-supported' status code.
Note: If Notification Recipients supplies this attribute, if
known, then the Event Notifications will be sent in time stamp
order since only one Subscription object is involved (see
"Event Notification Ordering" requirements in [ipp-ntfy]
section 9). Supplying this attribute also reduces the Event
processing time on the Printer since the Printer doesn't have
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to search all of the Subscription Objects in order to match the
"notify-recipient-uri" operation attribute (see next
attribute).
"notify-recipient-uri" (uri(255)):
The client MAY supply this attribute whether or not it also
supplies the "notify-subscription-id" operation attribute. The
Printer object MUST support this attribute. If the client
supplies neither the "notify-subscription-id" nor the "notify-
recipient-uri", the Printer MUST reject the request and return
the 'client-error-bad-request' status code.
If the supplied scheme is not ippget (case insensitive-match -
see section 11.5.2), the Printer MUST reject the request and
return the 'client-error-uri-scheme-not-supported' status code.
If the client also supplied the "notify-subscription-id"
attribute, then the value of this attribute MUST match the
"notify-recipient-uri" Subscription Description attribute for
the identified Subscription object. If they do not match, the
Printer MUST return the 'client-error-not-found' status code.
If the client did not supply the "notify-subscription-id"
operation attribute, the Printer matches the value of this
"notify-recipient-uri" attribute against the value of the
"notify-recipient-uri" Subscription Description attribute in
each Subscription Object in the Printer using the URI matching
rules specified in section 11.5.2. If there are no matches, the
IPP Printer MUST return the 'client-error-not-found' status
code.
The value of this attribute is defined to be shorter (255
octets) than the 'uri' attribute syntax (1023 octets) in
[RFC2911], since this uri is used for identification, not for
locating a network resource.
The [ipp-ntfy] specification REQUIRES that Subscription
Object's "notify-recipient-uri" attribute be returned in any
operation with the identical representation as supplied by the
original Subscribing Client in the Subscription Creation
Request. Therefore the Printer implementation MUST use other
means to perform the URI match than changing the Subscription
Object's original "notify-recipient-uri" value to a canonical
form.
Note: this attribute allows a subscribing client to pick URLs
that are unique, e.g. the client's own URL or a friend's URL,
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which in both cases is likely the URL of the person's host. An
application could make a URL unique for each application.
"notify-wait" (boolean):
The client MAY supply this attribute. The Printer object MUST
support both values of this attribute. If the value is 'true',
the client is requesting Event Wait Mode. See the beginning of
section 5 for the rules for Event Wait Mode.
5.2 Get-Notifications Response
The following groups of attributes are part of the Get-Notifications
Response:
Group 1: Operation Attributes
Status Message:
In addition to the REQUIRED status code returned in every
response, the response OPTIONALLY includes a "status-message"
(text(255)) and/or a "detailed-status-message" (text(MAX))
operation attribute as described in [RFC2911] sections 13 and
3.1.6.
The Printer can return any status codes defined in [RFC2911].
If the status code is not 'successful-xxx', the Printer MUST
NOT return any Event Notification Attribute groups. The
following is a description of the important status codes:
successful-ok: the response contains all Event Notification
associated with the specified "notify-recipient-uri". If
the specified Subscription Objects have no associated
Event Notification, the response MUST contain zero Event
Notifications.
client-error-not-found: The Printer has no Subscription
Object's whose "notify-recipient-uri" attribute equals
the "notify-recipient-uri" Operation attribute, if
supplied or whose "notify-subscription-id" attribute
equals the "notify-subscription-id" Operation attribute,
if supplied.
server-error-busy: The Printer is too busy to accept this
operation. If the "notify-get-interval" operation
attribute is present in the Operation Attributes of the
response, then the Notification Recipient SHOULD wait for
the number of seconds specified by the "notify-get-
interval" attribute before performing this operation
again. If the "notify-get-interval" Operation Attribute
is not present, the Notification Recipient SHOULD use the
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normal network back-off algorithms for determining when
to perform this operation again.
redirection-other-site: The Printer does not handle this
operation and requests the Notification Recipient to
perform the operation again with the uri specified by the
"redirect-uri" Operation Attribute in the response.
Natural Language and Character Set:
The "attributes-charset" and "attributes-natural-language"
attributes as described in [RFC2911] section 3.1.4.2.
The Printer MUST use the values of "notify-charset" and
"notify-natural-language", respectively, from one Subscription
Object associated with the Event Notifications in this
response.
Normally, there is only one matched Subscription Object, or the
value of the "notify-charset" and "notify-natural-language"
attributes is the same in all Subscription Objects. If not, the
Printer MUST pick one Subscription Object from which to obtain
the value of these attributes. The algorithm for picking the
Subscription Object is implementation dependent. The choice of
natural language is not critical because 'text' and 'name'
values can override the "attributes-natural-language" Operation
attribute. The Printer's choice of charset is critical because
a bad choice may leave it unable to send some 'text' and 'name'
values accurately.
"printer-up-time" (integer(1:MAX)):
The value of this attribute is the Printer's "printer-up-time"
attribute at the time the Printer sends this response. Because
each Event Notification also contains the value of this
attribute when the event occurred, the value of this attribute
lets a Notification Recipient know when each Event Notification
occurred relative to the time of this response.
"redirect-uri" (uri):
The value of this attribute is the uri that the Notification
Recipient MUST use for a subsequent Get-Notifications
operation. This attribute is returned in the Operation
Attributes Group if and only if the status code has the value
'redirection-other-site'.
Group 2: Unsupported Attributes
See [RFC2911] section 3.1.7 for details on returning
Unsupported Attributes.
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Group 3 through N: Event Notification Attributes
The Printer responds with one Event Notification Attributes
Group per matched Event Notification. The entire response is
considered a single Compound Event Notification (see [ipp-
ntfy]). The last Event Notification Attributes Group MAY
contain a single "notify-get-interval" (see section 7.1 and
12), in which case the Printer will return no future responses.
The initial matched Event Notifications are all un-expired
Event Notification associated with the matched Subscription
Objects and MUST follow the "Event Notification Ordering"
requirements for Event Notifications within a Compound Event
Notification specified in [ipp-ntfy] section 9.
If the Notification Recipient has selected the Event Wait Mode
option to wait for additional Event Notifications (the "notify-
wait" attribute was set to 'true'), the Printer sends
subsequent Event Notifications in the response each time it
processes additional Events. Each time the Printer sends such
Event Notifications, their ordering MUST follow the "Event
Notification Ordering" requirements in [ipp-ntfy] section 9.
Note: If a Notification Recipient performs two consecutive Get-
Notifications operations, the time stamp of the first Event
Notification in the second Get-Notifications Response may be
less than the time stamp of the last Event Notification in the
first Get-Notification Response. This happens because the
Printer sends all unexpired Event Notification according to the
ordering specified in [ipp-ntfy] and some Event Notifications
from the first Get-Notifications operation may not have expired
by the time the second Get-Notifications operation occurs.
From the Notification Recipient's view, the response appears as
an initial burst of data, which includes the Operation
Attributes Group and one Event Notification Attributes Group
per Event Notification that the Printer is holding. After the
initial burst of data, if the Notification Recipient has
selected the Event Wait Mode option to wait for additional
Event Notifications, the Notification Recipient receives
occasional Event Notification Attribute Groups. Proxy servers
may delay some Event Notifications or cause time-outs to occur.
The client MUST be prepared to perform the Get-Notifications
operation again when time-outs occur.
Each attribute is encoded using the IPP rules for encoding
attributes [RFC2910] and MAY be encoded in any order. Note:
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the Get-Jobs response in [RFC2911] acts as a model for encoding
multiple groups of attributes. See section 12 for the encoding
and transport rules.
Each Event Notification Group MUST contain all of attributes
specified in section 9.1 ("Content of Machine Consumable Event
Notifications") of [ipp-ntfy] with exceptions denoted by
asterisks in the tables below.
The tables below are copies of the tables in section 9.1
("Content of Machine Consumable Event Notifications") of [ipp-
ntfy] except that each cell in the "Sends" column is a "MUST".
For an Event Notification for all Events, the Printer includes
the attributes shown in Table 2.
Table 2 " Attributes in Event Notification Content
Source Value Sends Source Object
notify-subscription-id (integer(1:MAX)) MUST Subscription
notify-printer-uri (uri) MUST Subscription
notify-subscribed-event (type2 keyword) MUST Event
Notification
printer-up-time (integer(1:MAX)) MUST Printer
printer-current-time (dateTime) MUST * Printer
notify-sequence-number (integer (0:MAX)) MUST Subscription
notify-charset (charset) MUST Subscription
notify-natural-language (naturalLanguage) MUST Subscription
notify-user-data (octetString(63)) MUST ** Subscription
notify-text (text) MUST Event
Notification
attributes from the "notify-attributes" MUST *** Printer
attribute
attributes from the "notify-attributes" MUST *** Job
attribute
attributes from the "notify-attributes" MUST *** Subscription
attribute
* The Printer MUST send the "printer-current-time" attribute if
and only if it supports the "printer-current-time" attribute on
the Printer object.
** If the associated Subscription Object does not contain a
"notify-user-data" attribute, the Printer MUST send an octet-
string of length 0.
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*** If the "notify-attributes" attribute is present on the
Subscription Object, the Printer MUST send all attributes
specified by the "notify-attributes" attribute. Note: if the
Printer doesn't support the "notify-attributes" attribute, it
is not present on the associated Subscription Object.
For Event Notifications for Job Events, the Printer includes
the additional attributes shown in Table 3.
Table 3 " Additional Attributes in Event Notification Content for
Job Events
Source Value Sends Source
Object
job-id (integer(1:MAX)) MUST Job
job-state (type1 enum) MUST Job
job-state-reasons (1setOf type2 keyword) MUST Job
job-impressions-completed (integer(0:MAX)) MUST * Job
* The Printer MUST send the "job-impressions-completed"
attribute in an Event Notification only for the combinations of
Events and Subscribed Events shown in Table 4.
Table 4 " Combinations of Events and Subscribed Events for "job-
impressions-completed"
Job Event Subscribed Job Event
'job-progress' 'job-progress'
'job-completed' 'job-completed'
'job-completed' 'job-state-changed'
For Event Notification for Printer Events, the Printer includes
the additional attributes shown in Table 5.
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Table 5 " Additional Attributes in Event Notification Content for
Printer Events
Source Value Sends Source
Object
printer-state (type1 enum) MUST Printer
printer-state-reasons (1setOf type2 keyword) MUST Printer
printer-is-accepting-jobs (boolean) MUST Printer
6 Subscription Template Attributes
This section defines the Subscription object conformance requirements
for Printers.
6.1 Subscription Template Attribute Conformance
The 'ippget' Delivery Method has the same conformance requirements
for Subscription Template attributes as defined in [ipp-ntfy]. The
'ippget' Delivery Method does not define any addition Subscription
Template attributes.
6.2 Additional Information about Subscription Template Attributes
This section defines additional information about Subscription
Template attributes defined in [ipp-ntfy].
6.2.1 notify-recipient-uri (uri)
This section describes the syntax of the value of this attribute for
the 'ippget' Delivery Method. The syntax for values of this
attribute for other Delivery Method is defined in other Delivery
Method Documents.
In order to support the 'ippget' Delivery Method and Protocol, the
Printer MUST support the following syntax:
The 'ippget://' URI scheme. The remainder of the URI indicates
something unique about the Notification Recipient, such as its host
name or host address (and optional path) that the Printer uses to
match the "notify-recipient-uri" Operation attribute supplied in
the Get-Notifications request. See section 11 for a complete
definition of the syntax of the IPPGET URL.
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6.3 Subscription Description Attribute Conformance
The 'ippget' Delivery Method has the same conformance requirements
for Subscription Description attributes as defined in [ipp-ntfy].
The 'ippget' Delivery Method does not define any addition
Subscription Description attributes.
7 Attributes only in Event Notifications
This section defines attributes that exist only in Event
Notifications and do no exist in any IPP-defined objects.
7.1 "notify-get-interval" (integer(0:MAX))
The Printer returns this attribute to give the client an indication
of when to try another Get-Notifications request in the future. The
value of this attribute is the number of seconds that the
Notification Recipient SHOULD wait before trying the Get-
Notifications operation again. This value is intended to help the
client be a good network citizen.
The Printer MUST return this attribute by itself in a separate Event
Notification Attributes Group. The Printer MUST return this
attribute if and only if:
1. Printer busy case: the Printer returns the 'server-error-busy'
status code OR
2. No wait case: the Printer returns the 'successful-ok' status
code and the client either (1) supplied the "notify-wait"
attribute with a value of 'false' or (2) omitted the attribute
entirely OR
3. Printer leaves Event Wait Mode: the Printer returns the
'successful-ok' status code and the client supplied the "notify-
wait" attribute with the 'true value (Event Wait Mode) but the
Printer wants the client to disconnect (no wait), instead of
staying connected. The client MUST accept this response and
MUST disconnect. If the client does not disconnect, the Printer
SHOULD do so. The Printer returns this attribute for this case
only if the implementation does not want to keep the connection
open at this time. If the Printer wants the client to keep the
connection open and remain in Event Wait Mode, then the Printer
MUST NOT return this attribute in the response.
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8 Additional Printer Description Attributes
This section defines additional Printer Description attributes for
use with the 'ippget' Delivery Method.
8.1 ippget-event-time-to-live (integer(0:MAX))
This Printer Description attribute specifies the number of seconds
that a Printer keeps an Event Notification that is associated with
the 'ippget' Delivery Method.
The Printer MUST support this attribute if it supports the 'ippget'
Delivery Method.
The value of this attribute is the minimum number of seconds that
MUST elapse between the time the Printer creates an Event
Notification object for the 'ippget' Delivery Method and the time the
Printer discards the same Event Notification.
For example, assume the following:
1. a client performs a Job Creation operation that creates a
Subscription Object associated with this Delivery Method, AND
2. an Event associated with the new Job occurs immediately after
the Subscription Object is created, AND
3. the same client or some other client performs a Get-
Notifications operation N seconds after the Job Creation
operation.
Then, if N is less than the value of this attribute, the client(s)
performing the Get-Notifications operations can expect not to miss
any Event-Notifications, barring some unforeseen lack of memory space
in the Printer.
The value of this attribute also specifies the minimum number of
seconds that the Printer, if supporting the ippget Delivery Method,
MUST keep 'completed', 'canceled', or 'aborted' Job objects in the
Job Retention and/or Job History phases. See [RFC2911] section
4.3.7.1 and the discussion in [ipp-ntfy] 'job-completed' event) that
explains that a Notification Recipients can query the Job after
receiving a 'job-completed' Event Notification in order to find out
other information about the job that is completing. However, this
attribute has no effect on the Cancel-Subscription operation which
deletes the object immediately, whether or not it contain the ippget
scheme. Immediately thereafter, subsequent Get-Notifications
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Responses MUST NOT contain Event Notifications associated with the
cancelled Subscription object.
9 New Values for Existing Printer Description Attributes
This section defines additional values for existing Printer
Description attributes define in [ipp-ntfy].
9.1 notify-schemes-supported (1setOf uriScheme)
The following value for the "notify-schemes-supported" attribute is
added in order to support the new Delivery Method defined in this
document:
'ippget' - The IPP Notification Delivery Method defined in this
document.
9.2 operations-supported (1setOf type2 enum)
Table 6 lists the "operation-id" value defined in order to support
the new Get-Notifications operation defined in this document.
Table 6 " Operation-id assignments
Value Operation Name
0x001C Get-Notifications
10 New Status Codes
The following status codes are defined as extensions for this
Delivery Method and are returned as the status code of the Get-
Notifications operation.
10.1 redirection-other-site (0x0300)
This status code means that the Printer doesn't perform that Get-
Notifications operation and that the "redirect-uri" Operation
Attribute in the response contains the uri that the Notification
Recipient MUST use for performing the Get-Notifications operation.
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11 The IPPGET URL Scheme
This section defines the 'ippget' URL and the conformance
requirements for using it.
11.1 The IPPGET URL Scheme Applicability and Intended Usage
This section is intended for use in registering the 'ippget' URL
scheme with IANA and fully conforms to the requirements in [RFC2717].
This document defines the 'ippget'" URL (Uniform Resource Locator)
scheme for specifying a unique identifier for an IPP Client which
implements the IPP Get-Notifications operation specified in this
document (see section 5).
The intended usage of the 'ippget' URL scheme is COMMON.
11.2 The IPPGET URL Scheme Associated Port
None.
An 'ippget' URL behaves as a unique identifier for IPP Clients and is
NOT used to initiate any over-the-wire protocol associations.
See: IANA Port Numbers Registry [IANA-PORTREG].
11.3 The IPPGET URL Scheme Associated MIME Type
All IPP Get-Notifications operations (requests and responses) MUST be
conveyed in an 'application/ipp' MIME media type as registered in
[IANA-MIMEREG]. An 'ippget' URL MUST uniquely identify an IPP Client
that support this 'application/ipp' MIME media type.
See: IANA MIME Media Types Registry [IANA-MIMEREG].
11.4 The IPPGET URL Scheme Character Encoding
The 'ippget' URL scheme defined in this document is based on the ABNF
for the URI Generic Syntax [RFC2396] and further updated by [RFC2732]
and [RFC2373] (for IPv6 addresses in URLs). The 'ippget' URL scheme
is case-insensitive in the scheme and 'authority' part; however, the
'abs_path' part is case-sensitive, as in [RFC2396]. Code points
outside [US-ASCII] MUST be hex escaped by the mechanism specified in
[RFC2396].
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11.5 The IPPGET URL Scheme Syntax in ABNF
This document is intended for use in registering the 'ippget' URL
scheme with IANA and fully conforms to the requirements in [RFC2717].
This document defines the 'ippget' URL (Uniform Resource Locator)
scheme for specifying a unique identifier for an IPP Client which
implements IPP 'Get-Notifications' operation specified in this
document.
The intended usage of the 'ippget' URL scheme is COMMON.
The IPP protocol places a limit of 1023 octets (NOT characters) on
the length of a URI (see section 4.1.5 'uri' in [RFC2911]). An IPP
Printer MUST return the 'client-error-request-value-too-long' status
code (see section 13.1.4.10 in [RFC2911]) when a URI received in a
request is too long.
Note: IPP Clients and IPP Printers ought to be cautious about
depending on URI lengths above 255 bytes, because some older client
or proxy implementations might not properly support these lengths.
An 'ippget' URL MUST be represented in absolute form. Absolute URLs
always begin with a scheme name followed by a colon. For definitive
information on URL syntax and semantics, see "Uniform Resource
Identifiers (URI): Generic Syntax and Semantics" [RFC2396]. This
specification adopts the definitions of "authority", "abs_path",
"query", "reg_name", "server", "userinfo", and "hostport" from
[RFC2396], as updated by [RFC2732] and [RFC2373] (for IPv6 addresses
in URLs).
The 'ippget' URL scheme syntax in ABNF is as follows:
ippget_URL = "ippget:" "//" authority [ abs_path [ "?" query ]]
authority = server | reg_name
reg_name = 1*( unreserved | escaped | "$" | "," |
";" | ":" | "@" | "&" | "=" | "+" )
server = [ [ userinfo "@" ] hostport ]
userinfo = *( unreserved | escaped |
";" | ":" | "&" | "=" | "+" | "$" | "," )
hostport = host [ ":" port ]
abs_path = "/" path_segments
If the port is empty or not given, then no port is assumed. The
semantics are that the 'ippget' URL is a unique identifier for an IPP
Client that will retrieve IPP event notifications via the IPP Get-
Notifications operation.
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Note: The use of IP addresses in URLs SHOULD be avoided whenever
possible (see [RFC1900]).
11.5.1 IPPGET URL Examples
The following are examples of valid 'ippget' URLs for IPP Clients
(using DNS host names):
ippget://abc.com
ippget://abc.com/listener
ippget://bob@abc.com/listener/1232
Note: The use of IP addresses in URLs SHOULD be avoided whenever
possible (see [RFC1900]).
The IPP Client that creates the Subscription object and the
Notification Recipient have to agree on a unique IPPGET URL value in
order for the Get-Notifications operations to retrieve the proper
Event Notifications. Therefore, the choice of 'userinfo@hostport'
versus the simpler 'hostport' production in an 'ippget' URL may be
influenced by the intended usage.
If a given IPP Client creates an IPP Subscription object for event
notifications intended for retrieval by the same IPP Client, then the
simple 'hostport' production may be most appropriate. In this case,
the IPP Client and the Notification Recipient both know the
'hostport' of the client.
On the other hand, if a given IPP Client creates an IPP Subscription
object for event notifications intended for retrieval by a different
IPP Client, then the 'userinfo@hostport' production (using, for
example, the right-hand side of a 'mailto:' URL, see [RFC2368]) may
be most appropriate. For this case, a mail address serves as the
prior agreement on the IPPGET URL value between the IPP Client and
the Notification Recipient.
11.5.2 IPPGET URL Comparisons
When comparing two 'ippget' URLs to decide if they match or not,
an IPP Client or IPP Printer MUST use the same rules as those
defined for HTTP URI comparisons in [RFC2616].
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12 Encoding and Transport
This section defines the encoding and transport considerations for
this Delivery Method based on [RFC2910].
The encoding of a Get-Notifications Response is modeled the Get-Jobs
Response (see [RFC2911]). In a Get-Notifications Response, each
Event Notification Attributes Group MUST start with an 'event-
notification-attributes-tag' (see the section "Encodings of
Additional Attribute Tags" in [ipp-ntfy]), but only the last group
ends with an 'end-of-attributes-tag'. In addition, for Event Wait
Mode the multi-part/related is used to separate each multiple
response (in time) to a single Get-Notifications Request.
The Printer returns Get-Notification Response as follows:
1. If the Notification Recipient client did not request Event Wait
Mode ("notify-wait" = 'false' or omitted), the Printer ends the
response with an 'end-of-attributes-tag' (see [RFC2911] Get-Jobs
encoding) as with any operation response. The Notification
Recipient is expected to close the connection.
2. If the Notification Recipient client requests Event Wait Mode
("notify-wait" = 'true') and the Printer wishes to honor the
request, the Printer ends the Response without an 'end-of-
attributes-tag' and MUST return the response as an
application/ipp part inside a multi-part/related MIME media
type. Neither the Notification Recipient nor the Printer close
the connection. When one or more additional Events occur, the
Printer returns each as an additional Event Notification Group
using a separate application/ipp part under the multi-
part/related type.
3. If the client requested Event Wait Mode ("notify-wait" =
'true'), but the Printer does not wish to honor the request in
the initial response but wants the client to disconnect, the
Printer MUST return the "notify-get-interval" attribute (see
section 7.1) as the last Event Notifications Attributes Group -
see section 5.2), the Printer ends the Response with an 'end-of-
attributes-tag'. The Printer returns the response as an
application/ipp part which MAY be inside an multi-part/related
type. The client MUST accept this response and MUST disconnect.
If the client does not disconnect, the Printer SHOULD do so.
4. If the client requested Event Wait Mode ("notify-wait" =
'true'), and the Printer initially honored the request, but
later wishes to leave Event Wait Mode, the Printer MUST return
the "notify-get-interval" attribute (see section 7.1) as the
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last Event Notifications Attributes Group - see section 5.2),
the Printer ends the Response with an 'end-of-attributes-tag'.
The Printer returns the response as an application/ipp part
which MUST be inside an multi-part/related type.
ISSUE: Should we use application/multiplexed (draft-herriot-
application-multiplexed-03.txt) which can chunk mime types using
content lengths, instead of multi-part/related, which uses boundary
strings?
Note: either the Notification Recipient or the Printer can abnormally
terminate by closing the connection. However, if the Printer closes
the connection too soon after returning the response, the client may
not receive the response.
The Printer MAY chunk the responses, but this has no significance to
the IPP semantics.
This notification delivery method uses the IPP transport and encoding
[RFC2910] for the Get-Notifications operation with one extension
allocated in [ipp-ntfy]:
Table 7 " The "event-notification-attributes-tag" value
Tag Value (Hex) Meaning
0x07 "event-notification-attributes-tag"
13 Conformance Requirements
The 'ippget' Delivery Method is RECOMMEND for Printers to support.
13.1 Conformance for IPP Printers
IPP Printers that conform to this specification:
1. MUST meet the conformance requirements defined in [ipp-ntfy];
2. MUST support the Get-Notifications operation defined in section
5;
3. MUST support the Subscription object attributes as defined in
section 6;
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4. MUST support the additional values for IPP/1.1 Printer
Description attributes defined in section 9;
#@# next line is > 72 characters: 73
5. MUST support the "ippget-event-time-to-live" Printer Description
attribute defined in section 8.1;
6. MUST support the "redirection-other-site" status code defined
10.1, if it redirects Get-Notifications operations;
7. SHOULD reject received 'ippget' URLs in 'application/ipp'
request bodies (e.g., in the "notify-recipient-uri" attribute in
a Get-Notifications request) that do not conform to the ABNF for
'ippget' URLs specified in section 11.5 of this document;
8. MUST listen for the IPP Get-Notifications operation requests on
IANA-assigned well-known port 631, unless explicitly configured
by system administrators or site policies;
9. SHOULD NOT listen for IPP Get-Notifications operation requests
on any other port, unless explicitly configured by system
administrators or site policies.
13.2 Conformance for IPP Clients
IPP Clients that conform to this specification:
1. MUST create unambiguously unique 'ippget' URLs in all cases;
2. MUST send 'ippget' URLs (e.g., in the "notify-recipient-uri"
attribute in a Get-Notifications request) that conform to the
ABNF specified in section 11.5 of this document;
3. MUST send IPP Get-Notifications operation requests via the port
specified in the associated 'ipp' URL (if present) or otherwise
via IANA assigned well-known port 631;
4. MUST convert the associated 'ipp' URLs for use in IPP Get-
Notifications operation to their corresponding 'http' URL forms
for use in the HTTP layer according to the rules in section 5
"IPP URL Scheme" in [RFC2910].
Note: The use of ambiguous 'ippget' URLs is NOT an optional feature
for IPP Clients; it is a non-conformant implementation error.
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14 IANA Considerations
IANA shall register the 'ippget' URL scheme as defined in section 11
according to the procedures of [RFC2717].
The rest of this section contains the exact information for IANA to
add to the IPP Registries according to the procedures defined in RFC
2911 [RFC2911] section 6.
Note to RFC Editors: Replace RFC NNNN below with the RFC number
for this document, so that it accurately reflects the content of
the information for the IANA Registry.
14.1 Operation Registrations
The following table lists the operation defined in this document.
This is to be registered according to the procedures in RFC 2911
[RFC2911] section 6.4.
Operations: Ref. Section:
Get-Notifications operation RFC NNNN 5
The resulting operation registration will be published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/operations/
area.
14.2 Additional attribute value registrations for existing attributes
This section lists additional attribute value registrations for use
with existing attributes defined in other documents.
14.2.1 Additional values for the "notify-schemes-supported" Printer
attribute
The following table lists the uriScheme value defined in this
document as an additional uriScheme value for use with the "notify-
schemes-supported" Printer attribute defined in [ipp-ntfy]. This
is to be registered according to the procedures in RFC 2911 [RFC2911]
section 6.1.
uriScheme Attribute Values: Ref. Section:
ippget RFC NNNN 9.1
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The resulting URI scheme attribute value registrations will be
published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-
values/notify-schemes-supported/
area.
14.2.2 Additional values for the "operations-supported" Printer
attribute
The following table lists the enum attribute value defined in this
document as an additional type2 enum value for use with the
"operations-supported" Printer attribute defined in [RFC2911]. This
is to be registered according to the procedures in RFC 2911 [RFC2911]
section 6.1.
type2 enum Attribute Values: Value Ref. Section:
Get-Notifications 0x001C RFC NNNN 9.2
The resulting enum attribute value registration will be published in
the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attribute-
values/operations-supported/
area.
14.3 Attribute Registrations
The following table lists the attribute defined in this document.
This is to be registered according to the procedures in RFC 2911
[RFC2911] section 6.2.
Printer Description attributes: Ref. Section:
ippget-event-time-to-live (integer(0:MAX)) RFC NNNN 8.1
The resulting attribute registration will be published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/attributes/
area.
14.4 Status code Registrations
The following table lists the status code defined in this document.
This is to be registered according to the procedures in RFC 2911
[RFC2911] section 6.6.
Status codes: Ref. Section:
redirection-other-site (0x0300) RFC NNNN 10.1
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The resulting status code registration will be published in the
ftp://ftp.iana.org/in-notes/iana/assignments/ipp/status-codes/
area.
15 Internationalization Considerations
The IPP Printer MUST localize the "notify-text" attribute as
specified in section 14 of [ipp-ntfy].
In addition, when the client receives the Get-Notifications response,
it is expected to localize the attributes that have the 'keyword'
attribute syntax according to the charset and natural language
requested in the Get-Notifications request.
16 Security Considerations
The IPP Model and Semantics document [RFC2911] discusses high-level
security requirements (Client Authentication, Server Authentication
and Operation Privacy). Client Authentication is the mechanism by
which the client proves its identity to the server in a secure
manner. Server Authentication is the mechanism by which the server
proves its identity to the client in a secure manner. Operation
Privacy is defined as a mechanism for protecting operations from
eavesdropping.
Unlike other Event Notification delivery methods in which the IPP
Printer initiates the Event Notification, with the method defined in
this document, the Notification Recipient is the client who s the
Get-Notifications operation. Therefore, there is no chance of "spam"
notifications with this method. Furthermore, such a client can close
down the HTTP channel at any time, and so can avoid future unwanted
Event Notifications at any time.
17 References
[ipp-iig]
Hastings, T., Manros, C., Kugler, K, Holst H., Zehler, P.,
"Internet Printing Protocol/1.1: draft-ietf-ipp-implementers-
guide-v11-03.txt, work in progress, July 17, 2001
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[ipp-ntfy]
R. Herriot, Hastings, T., Isaacson, S., Martin, J., deBry, R.,
Shepherd, M., Bergman, R., "Internet Printing Protocol/1.1: IPP
Event Notifications and Subscriptions", <draft-ietf-ipp-not-spec-
07.txt>, July 17, 2001.
[RFC1900]
B. Carpenter, Y. Rekhter. Renumbering Needs Work, RFC 1900,
February 1996.
[RFC2026]
S. Bradner, "The Internet Standards Process -- Revision 3", RFC
2026, October 1996.
[RFC2119]
S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119 , March 1997
[RFC2368]
P. Hoffman, L. Masinter, J. Zawinski. The "mailto" URL Scheme, RFC
2368, July 1998.
[RFC2373]
R. Hinden, S. Deering. IP Version 6 Addressing Architecture, RFC
2373, July 1998.
[RFC2396]
Berners-Lee, T. et al. Uniform Resource Identifiers (URI): Generic
Syntax, RFC 2396, August 1998
[RFC2565]
Herriot, R., Butler, S., Moore, P., and R. Turner, "Internet
Printing Protocol/1.0: Encoding and Transport", RFC 2565, April
1999.
[RFC2566]
R. deBry, T. Hastings, R. Herriot, S. Isaacson, and P. Powell,
"Internet Printing Protocol/1.0: Model and Semantics", RFC 2566,
April 1999.
[RFC2567]
Wright, D., "Design Goals for an Internet Printing Protocol", RFC
2567, April 1999.
[RFC2568]
Zilles, S., "Rationale for the Structure and Model and Protocol for
the Internet Printing Protocol", RFC 2568, April 1999.
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[RFC2569]
Herriot, R., Hastings, T., Jacobs, N., Martin, J., "Mapping between
LPD and IPP Protocols", RFC 2569, April 1999.
[RFC2616]
R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P.
Leach, T. Berners-Lee, "Hypertext Transfer Protocol - HTTP/1.1",
RFC 2616, June 1999.
[RFC2717]
R. Petke and I. King, "Registration Procedures for URL Scheme
Names", RFC 2717, November 1999.
[RFC2732]
R. Hinden, B. Carpenter, L. Masinter. Format for Literal IPv6
Addresses in URL's, RFC 2732, December 1999.
[RFC2910]
Herriot, R., Butler, S., Moore, P., Tuner, R., "Internet Printing
Protocol/1.1: Encoding and Transport", RFC 2910, September 2000.
[RFC2911]
R. deBry, T. Hastings, R. Herriot, S. Isaacson, P. Powell,
"Internet Printing Protocol/1.1: Model and Semantics", RFC 2911,
September 2000.
18 Authors' Addresses
Robert Herriot
Xerox Corp.
3400 Hill View Ave, Building 1
Palo Alto, CA 94304
Phone: 650-813-7696
Fax: 650-813-6860
e-mail: robert.herriot@pahv.xerox.com
Carl Kugler
IBM
P.O. Box 1900
Boulder, CO 80301-9191
Phone:
Fax:
e-mail: kugler@us.ibm.com
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Harry Lewis
IBM
P.O. Box 1900
Boulder, CO 80301-9191
Phone: 303-924-5337
FAX:
e-mail: harryl@us.ibm.com
IPP Web Page: http://www.pwg.org/ipp/
IPP Mailing List: ipp@pwg.org
To subscribe to the ipp mailing list, send the following email:
1) send it to majordomo@pwg.org
2) leave the subject line blank
3) put the following two lines in the message body:
subscribe ipp
end
Implementers of this specification document are encouraged to join
the IPP Mailing List in order to participate in any discussions of
clarification issues and review of registration proposals for
additional attributes and values. In order to reduce spam the
mailing list rejects mail from non-subscribers, so you must subscribe
to the mailing list in order to send a question or comment to the
mailing list.
19 Description of Base IPP documents
The base set of IPP documents includes:
Design Goals for an Internet Printing Protocol [RFC2567]
Rationale for the Structure and Model and Protocol for the Internet
Printing Protocol [RFC2568]
Internet Printing Protocol/1.1: Model and Semantics [RFC2911]
Internet Printing Protocol/1.1: Encoding and Transport [RFC2910]
Internet Printing Protocol/1.1: Implementer's Guide [ipp-iig]
Mapping between LPD and IPP Protocols [RFC2569]
Internet Printing Protocol (IPP): IPP Event Notifications and
Subscriptions [ipp-ntfy]
The "Design Goals for an Internet Printing Protocol" document takes a
broad look at distributed printing functionality, and it enumerates
real-life scenarios that help to clarify the features that need to be
included in a printing protocol for the Internet. It identifies
requirements for three types of users: end users, operators, and
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administrators. It calls out a subset of end user requirements that
are satisfied in IPP/1.0. A few OPTIONAL operator operations have
been added to IPP/1.1.
The "Rationale for the Structure and Model and Protocol for the
Internet Printing Protocol" document describes IPP from a high level
view, defines a roadmap for the various documents that form the suite
of IPP specification documents, and gives background and rationale
for the IETF working group's major decisions.
The "Internet Printing Protocol/1.1: Model and Semantics" document
describes a simplified model with abstract objects, their attributes,
and their operations that are independent of encoding and transport.
It introduces a Printer and a Job object. The Job object optionally
supports multiple documents per Job. It also addresses security,
internationalization, and directory issues.
The "Internet Printing Protocol/1.1: Encoding and Transport" document
is a formal mapping of the abstract operations and attributes defined
in the model document onto HTTP/1.1 [RFC2616]. It defines the
encoding rules for a new Internet MIME media type called
"application/ipp". This document also defines the rules for
transporting over HTTP a message body whose Content-Type is
"application/ipp". This document defines the 'ippget' scheme for
identifying IPP printers and jobs.
The "Internet Printing Protocol/1.1: Implementer's Guide" document
gives insight and advice to implementers of IPP clients and IPP
objects. It is intended to help them understand IPP/1.1 and some of
the considerations that may assist them in the design of their client
and/or IPP object implementations. For example, a typical order of
processing requests is given, including error checking. Motivation
for some of the specification decisions is also included.
The "Mapping between LPD and IPP Protocols" document gives some
advice to implementers of gateways between IPP and LPD (Line Printer
Daemon) implementations.
The "IPP Event Notifications and Subscriptions" document defines an
extension to IPP/1.0 [RFC2566, RFC2565] and IPP/1.1 [RFC2911,
RFC2910]. This extension allows a client to subscribe to printing
related Events and defines the semantics for delivering asynchronous
Event Notifications to the specified Notification Recipient via a
specified Delivery Method (i.e., protocols) defined in (separate)
Delivery Method documents.
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20 Full Copyright Statement
Copyright (C) The Internet Society (2001). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
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 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.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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