Internet Printing Protocol (IPP): Requirements for Job, Printer, and Device Administrative Operations

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.

Table of Contents

   1  Introduction.....................................................2
   2  Terminology......................................................2
   3  Requirements and Use Cases.......................................3
   4  IANA Considerations.............................................10
   5  Internationalization Considerations.............................10
   6  Security Considerations.........................................10
   7  References......................................................11
   Appendix A: Description of base IPP documents......................12
   Authors' Addresses.................................................14
   Full Copyright Statement...........................................15

List of Tables

   Table 1 - List of Printer Operations and corresponding Device
      Operations ..................................................... 9

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:  kugler@us.ibm.com


   Tom Hastings
   Xerox Corporation
   737 Hawaii St.  ESAE 231
   El Segundo, CA  90245

   Phone: 310-333-6413
   Fax: 310-333-5514
   EMail: hastings@cp10.es.xerox.com


   Harry Lewis
   IBM
   Boulder CO

   Phone: (303) 924-5337
   EMail:  harryl@us.ibm.com

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