RFC3239
Network Working Group C. Kugler Request for Comments: 3239 H. Lewis Category: Informational IBM Corporation
T. Hastings
Xerox Corporation
February 2002
Internet Printing Protocol (IPP): Requirements for Job, Printer, and Device Administrative Operations
Status of this Memo
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document specifies the requirements and uses cases for some optional administrative operations for use with the Internet Printing Protocol (IPP) version 1.0 and version 1.1. Some of these administrative operations operate on the IPP Job and Printer objects. The remaining operations operate on a new Device object that more closely models a single output device.
List of Tables
Table 1 - List of Printer Operations and corresponding Device
1 Introduction
The Internet Printing Protocol (IPP) is an application level protocol that can be used for distributed printing using Internet tools and technologies. IPP version 1.1 ([RFC2911, RFC2910]) focuses on end user functionality with a few administrative operations included (for a description of the base IPP documents, see Appendix A). This document defines the requirements and use cases for additional optional end user, operator, and administrator operations used to control Job objects, Printer objects (see RFC2911) and a new Device object. The new Device object more closely models a single output device and has no notion of a job, while the Printer object models a print service which understands jobs and may represent one or more output devices.
The scope of IPP is characterized in RFC 2567 RFC2567 "Design Goals for an Internet Printing Protocol". It is not the intent of this document to revise or clarify this scope or conjecture as to the degree of industry adoption or trends related to IPP within printing systems. It is the intent of this document to extend the original set of operations - in a similar fashion to the Set1 extensions which referred to IPP/1.0 and were later incorporated into IPP/1.1.
2 Terminology
This section defines terminology used throughout this document and the corresponding documents that define the Administrative operations on Job, Printer, and Device objects.
This document uses terms such as "client", "Printer", "Job", "attributes", "keywords", and "support". These terms have special meaning and are defined in the model terminology RFC2911 section 12.2.
In addition, the following capitalized terms are defined:
IPP Printer object (or Printer for short) - a software abstraction
defined by RFC2911.
Printer Operation - an operation whose target is an IPP Printer
object and whose effect is on the Printer object.
Output Device - the physical imaging mechanism that an IPP Printer
controls. Note: while this term is capitalized in this
specification (but not in RFC2911), there is no formal object
called an Output Device.
Device Operation - an operation whose target is an IPP Printer
object and whose defined effect is on an Output Device.
Output Device Fan-Out - a configuration in which an IPP Printer
controls more that one output-device.
Printer fan-out - a configuration in which an IPP Printer object
controls more than one Subordinate IPP Printer object.
Printer fan-in - a configuration in which an IPP Printer object is
controlled by more than one IPP Printer object.
Subordinate Printer - an IPP Printer object that is controlled by
another IPP Printer object. Such a Subordinate Printer may
have one or more Subordinate Printers.
Leaf Printer - a Subordinate Printer that has no Subordinate
Printers.
Non-Leaf Printer - an IPP Printer object that has one or more
Subordinate Printers.
Chained Printer - a Non-Leaf Printer that has exactly one
Subordinate Printer.
Job Creation operations - IPP operations that create a Job object:
Print-Job, Print-URI, and Create-Job.
3 Requirements and Use Cases
The Administrative operations for Job and Printer objects will be defined in one document [ipp-ops-set2]. The Administrative operations for Device objects will be defined in a separate document. The requirements are presented here together to show the parallelism.
1. Have separate operations for affecting the IPP Printer
versus affecting the Output Device, so its clear what the
intent of each is, and implementers can implement one or the
other or both.
2. Support fan-out of Printer objects.
3. Support fan-out of Output Devices.
4. Support fan-in of Printer objects, as long as it doesn't
make the semantics more complicated when not supporting
fan-in.
5. Support fan-in of output objects, as long as it doesn't make
the semantics more complicated when not supporting fan-in.
6. Instead of having operation attributes that alter the
behavior of the operation significantly, have separate
operations, so that it is simple and clear to a client which
semantics the Printer is supporting (by querying the
"operations-supported" attribute) and it is simple to
describe the capabilities of a Printer implementation in
written documentation (just list the optional operations
supported).
7. Need a Printer Operation to prevent a Printer object from
accepting new IPP jobs, but currently accepted jobs continue
unaffected to be scheduled and processed. Need a companion
one to restore the Printer object to accept new IPP jobs.
Usage: Operator is preparing to take the IPP Printer out of
service or to change the configuration of the IPP Printer.
Suggested name and operations: Disable-Printer and Enable-
Printer
8. Need a Device Operation to prevent an Output Device from
accepting any new jobs from any job submission protocol and
a companion one to restore the Output Device to accepting
any jobs.
Usage: Operator is preparing to take the Output Device out
of service.
Suggested name and operations: Disable-Device and Enable
Device
9. Need a Printer Operation to stop the processing after the
current IPP job completes and not start processing any
additional IPP jobs (either by scheduling the jobs or
sending them to the Output Device), but continue to accept
new IPP jobs. Need a companion operation to start
processing/sending IPP jobs again.
Usage: Operator wants to gracefully stop the IPP Printer at
the next job boundary. The Pause-Printer-After-Current-Job
operation is also invoked implicitly by the Deactivate-
Printer and the Shutdown-Printer Operations.
Suggested name and operations: Pause-Printer-After-
Current-Job, (IPP/1.1) Resume-Printer
10. Need a Device Operation to stop the processing the current
job "immediately", no matter what protocol. Its like the
Pause button on the Output Device. This operation is for
emergencies. The stop point depends on implementation, but
can be mid page, end of page, end of sheet, or after a few
sheets for Output Devices that can't stop that quickly. The
paper path isn't run out. Need a companion operation to
start processing the current any-protocol job without losing
any thing.
Usage: Operator sees something bad about to happen, such as
the paper is about to jam, or the toner is running out, or
the device is overheating or wants to add more paper.
Suggested name and operations: Pause-Device-Now, Resume-
Device
11. Need a Printer Operation to stop the processing of IPP jobs
after all of the currently accepted jobs have been
processed, but any newly accepted jobs go into the
'processing-held' state.
Usage: This allows an operator to reconfigure the Output
Device in order to let jobs that are held waiting for
resources, such as special media, get a chance. Then the
operator uses another operation after reconfiguring. He
repeats the two operations to restore the Output Device to
its normal media.
Suggested name and operations: Hold-New-Jobs, Release-
Held-New-Jobs
12. Need a Device Operation to stop processing the current any-
protocol job at a convenient point, such as after the
current copy (or end of job if last or only copy). Need a
companion operation to start processing the current any-
protocol job or next job without losing any thing.
Usage: The operator wants to empty the output bin that is
near full. The paper path is run out.
Suggested name and operations: Pause-Device-After-Current-
Copy, Resume-Device
13. Need a Device Operation that always pauses on a device-
defined boundary, no matter how many copies, in order to not
break up a job. Need a companion operation to start
processing the current any-protocol job or next job without
losing any thing.
Usage: The operator wants to empty the output bin that is
near full, but he doesn't want to break up a job in case it
has multiple copies. The paper path is run out.
Suggested name and operations: Pause-Device-After-Current-
Job, Resume-Device
14. Need a Printer Operation that combines Disable-Printer,
Pause-Printer-After-Current-Job, and rejects all other Job,
Printer, and Device Operations, except Job and Printer
queries, System Administrator Set-Printer-Attributes, and
the companion operation to resume activity. In other words,
this operation makes the Printer a read-only object in a
graceful manner for end-users and the operator.
Usage: The administrator wants to reconfigure the Printer
object using the Set-Printer-Attributes operation without
disturbing the current in process work, but wants to make
sure that the operator isn't also trying to change the
Printer object as part of running the Printer.
Suggested name and operation: Deactivate-Printer,
Activate-Printer
15. Need a Device Operation that combines Disable-Device,
Pause-Device-After-Current-Job, and rejects all other Device
Operations, except Job and Printer queries and the companion
operation to resume activity. In other words, this
operation makes the Output Device a read-only object in a
graceful manner.
Usage: The field service person wants to open up the device
without disturbing the current in process work, perhaps to
replace staples, or replace the toner cartridge.
Suggested name and operation: Deactivate-Device, Activate-
Device
16. Need a Printer Operation to recover from the IPP Printer
software that has gotten confused (run out of heap memory or
gotten into a state that it doesn't seem to be able to get
out of). This is a condition that shouldn't happen, but
does in real life. Any volatile information is saved if
possible before the software is re-initialized. No
companion operation is needed to undo this. We don't want
to go back to the "confused" state :-).
Usage: The IPP Printer software has gotten confused or
isn't responding properly.
Suggested name and operation: Restart-Printer
17. Need a Device Operation to recover from the Output Device
hardware and software that has gotten confused (gotten into
a state that it doesn't seem to be able to get out of, run
out of heap memory, etc.). This is a condition that
shouldn't happen, but does in real life. This is the same
and has the same options as the Printer MIB reset. No
companion operation is needed to undo this. We don't want
to go back to the "confused" state :-).
Usage: The Output Device has gotten confused or need
resetting to some initial conditions.
Suggested name and operation: Reset-Device
18. Need a Printer Operation to put the IPP Printer object out
of business with no way in the protocol to bring that
instantiation back to life (but see Startup-Printer which
brings up exactly one new instantiation to life with the
same URL). Any volatile information is saved if possible.
Usage: The Printer is being moved or the building's power
is being shut off.
Suggested name and operation: Shutdown-Printer
19. Need a Printer Operation to bring an IPP Printer to life
when there is an already running host.
Usage: After the host is started (by means outside the IPP
protocol), the operator is able to ask the host to bring up
any number of Printer objects (that the host has been
configured in some way) each with distinct URLs.
Suggested name and operation: Startup-Printer
20. Need a Device Operation to power off the Output Device after
writing out any software state. It is assumed that other
operations have more gracefully prepared the Output Device
for this drastic and immediate. There is no companion
Device Operation to bring the power back on.
Usage: The Output Device is going to be moved, the power in
the building is going to be shutoff, the repair man has
arrived and needs to take the Output Device apart.
Suggested name and operation: Power-Off-Device
21. Need a Device Operation to startup a powered-off device.
Usage: After a Power-Off-Device, if the device can be
powered back up (possibly by an intervening host that
supports the Device Operation).
Suggest name and operation: Power-On-Device
The tentative list of Printer and the corresponding Device Operations is shown in Table 1:
Table 1 - List of Printer Operations and corresponding Device
Operations
Printer Operation Corresponding Device Operation
equivalent
Disable-Printer Disable-Device
Enable-Printer Enable-Device
Pause-Printer (IPP/1.1 - RFC2911 Pause-Device-Now - one interpretation)
no Pause-Device-After-Current-Copy
Pause-Printer-After-Current-Job Pause-Device-After-Current-Job
Resume-Printer (IPP/1.1 - Resume-Device RFC2911)
Hold-New-Jobs no
Release-Held-New-Jobs no
Deactivate-Printer Deactivate-Device
Activate-Printer Activate-Device
Purge-Jobs (IPP/1.1 - RFC2911) Purge-Device
Restart-Printer Reset-Device
Shutdown-Printer Power-Off-Device
Startup-Printer Power-On-Device
There are no conformance dependencies between Printer Operations and Device Operations. Either may be supported without supporting the corresponding operations.
4 IANA Considerations
This document does not define anything to be registered. When a document is produced that defines operations that meet the requirements in this document, those operations will be registered according to the procedures in RFC2911 section 6.4.
5 Internationalization Considerations
This document has the same localization considerations as the RFC2911.
6 Security Considerations
This document defines the requirements for operations that are intended to be used by an operator or system administrator. These operations, when defined, would affect how the Printer behaves and establish policy and/or operating behavior that ordinary users shouldn't be able to perform. Printer implementations that support such operations should authenticate users and authorized them as being an operator or a system administrator for the system. Otherwise, unprivileged users could affect the policy and behavior of IPP Printers, thereby affecting other users. Similarly clients that supports such operations should be prepared to provide the necessary authentication information. See the security provisions in RFC2911 for authentication, such as TLS.
7 References
[ipp-ntfy] Herriot, R., Hastings, T., Isaacson, S., Martin, J.,
deBry, R., Shepherd, M. and R. Bergman, "Internet
Printing Protocol/1.1: IPP Event Notifications and
Subscriptions", Work in Progress.
[ipp-ops-set2] Kugler, C., Hastings, T. and H. Lewis, "Internet
Printing Protocol (IPP): Job and Printer
Administrative Operations", Work in Progress.
RFC2565 Herriot, R., Butler, S., Moore, P. and R. Tuner,
"Internet Printing Protocol/1.0: Encoding and
Transport", RFC 2565, April 1999.
RFC2566 deBry, R., Hastings, T., Herriot, R. and S. Isaacson,
P. Powell, "Internet Printing Protocol/1.0: Model and
Semantics", RFC 2566, April 1999.
RFC2567 Wright, D., "Design Goals for an Internet Printing
Protocol", RFC 2567, April 1999.
RFC2568 Zilles, S., "Rationale for the Structure and Model and
Protocol for the Internet Printing Protocol", RFC
2568, April 1999.
RFC2569 Herriot, R., Hastings, T., Jacobs, N. and J. Martin,
"Mapping between LPD and IPP Protocols", RFC 2569, April 1999.
RFC2616 Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P. and T. Berners-Lee, "Hypertext
Transfer Protocol - HTTP/1.1", RFC 2616, June 1999.
RFC2910 Herriot, R., Butler, S., Moore, P. and R. Tuner,
"Internet Printing Protocol/1.1: Encoding and
Transport", RFC 2910, September 2000.
RFC2911 deBry, R., Hastings, T., Herriot, R., Isaacson, S. and
P. Powell, "Internet Printing Protocol/1.0: Model and
Semantics", RFC 2911, September 2000.
RFC3196 Hastings, T., Manros, C., Zehler, P., Kuger, C. and H.
Holst, "Internet Printing Protocol/1.1: Implementer's
Guide", RFC 3196, November 2001.
Appendix A: 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 RFC3196 Mapping between LPD and IPP Protocols RFC2569 Internet Printing Protocol (IPP): IPP Event Notifications and Subscriptions [ipp-ntfy]
The "Design Goals for an Internet Printing Protocol" document takes a broad look at distributed printing functionality, and it enumerates real-life scenarios that help to clarify the features that need to be included in a printing protocol for the Internet. It identifies requirements for three types of users: end users, operators, and administrators. It calls out a subset of end user requirements that are satisfied in IPP/1.0. 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.
Authors' Addresses
Carl Kugler IBM Boulder CO
Phone: (303) 924-5060 EMail: [email protected]
Tom Hastings Xerox Corporation 737 Hawaii St. ESAE 231 El Segundo, CA 90245
Phone: 310-333-6413 Fax: 310-333-5514 EMail: [email protected]
Harry Lewis IBM Boulder CO
Phone: (303) 924-5337 EMail: [email protected]
IPP Web Page: http://www.pwg.org/ipp/ IPP Mailing List: [email protected]
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