IPP> OPS - Updated IPP Additional Admin operations notes and agreement s

IPP> OPS - Updated IPP Additional Admin operations notes and agreement s

IPP> OPS - Updated IPP Additional Admin operations notes and agreement s

Hastings, Tom N hastings at cp10.es.xerox.com
Fri Jul 16 21:37:33 EDT 1999


This updated document includes agreements reached at the 7/14/99 IPP
telecon.  I'll produce an updated version early next week for review
at our 7/28/99 telecon.

I've also copied these agreements to:

ftp://ftp.pwg.org/pub/pwg/ipp/proposed-registrations/operations/ipp-ops-admi
n-agreements-990716-rev.doc
ftp://ftp.pwg.org/pub/pwg/ipp/proposed-registrations/operations/ipp-ops-admi
n-agreements-990716-rev.pdf
ftp://ftp.pwg.org/pub/pwg/ipp/proposed-registrations/operations/ipp-ops-admi
n-agreements-990716.txt




           Notes and Agreements on Admin operations, 7/16/99

From: Bob Herriot and Tom Hastings
Date: 07/16/1999
File: ipp-ops-admin-agreements-990716.doc

This updated document includes agreements reached at the 7/14/99 IPP
telecon.  Agreements that have no comments indicate that the telecon
also agreed with the WG meeting.

Bob Herriot led the IPP review of the Additional Administrative
Operations document, dated June 30, 1999, at the 7/7/99-7/8/99 IETF IPP
WG meeting on Copenhagen.  He generated the following notes and
agreements that were reached.  The unnumbered issues are new issues
raised.  The number issues refer to the numbered issues in the
specification.  Unresolved ISSUES are highlighted like this in the .doc
and .pdf files.

The document being reviewed is available at:

ftp://ftp.pwg.org/pub/pwg/ipp/proposed-registrations/operations/ipp-ops-admi
n-990630.pdf

As always, these agreements are being sent to the IPP DL for further
discussion and final consensus.

1.ISSUE:  What happens if the value for the from-operator-message for
  job or printer is either a blank or an empty string for the set
  operation or other operations that set this attribute?

  Suggested resolution:  If the operation attribute or the explicit
  "printer-message-from-operator" (or "job-message-from-operator") is
  supplied in the request, but with either a zero-length or white space
  only content, it replaces the existing Printer or Job attribute as
  expected.  This is the way that the operation can indicate that there
  is no longer a message from the operator for the Printer or Job
  object.  However, if the operation attribute or the explicit
  "printer-message-from-operator" (or "job-message-from-operator") is
  NOT supplied in the request, the corresponding Printer or Job
  attribute is unchanged.

2. Printer and job operator message should also have a tick time, which
  is required. Date-time value should be required if the printer
  implements the current-date-time.

3. ISSUE: Can a client determine the values of "when" that are supported
  for operations (Pause-Printer, Reset-Printer, and Shutdown-Printer)?
  
  We did not resolve this issue, since there could be different values
  of "when" for the three different operations.  Adding three "when-
  xxx" Printer Description attributes is a possibility, but does seem
  overkill.

4. ISSUE 1:  The 'after-current-job' value of the "when" operation
  attribute must be supported.

5. ISSUE:  In 13.1.5.8 server-error-printer-is-in-standby-mode, when
  Printer has been shutdown in 'standby-mode' (as opposed to "shutdown-
  function" = 'power-down'), :  Restart-Printer and Get-Printer-
  Attributes work, but does Set work?
  
  Suggested resolution:  We agreed that Restart-Printer and Get-
  Printer-Attributes must work.  We also agreed, that the purpose of
  Shutdown-Printer to 'standby' mode, was long-term, not just a short
  time to, say, change a Printer attribute or change a loaded medium.
  However, on Restart-Printer (the next day), the operation or system
  administrator might want to change some attributes before allowing
  jobs to be submitted or already submitted jobs to be scheduled.
  Therefore, we have the following issue:

  ISSUE:   What state the Printer comes back up on Restart-Printer and
  how can the client control?
  Possible alternatives:
     
  a. Restart-Printer always brings the Printer up Disabled ("printer-
  is-accepting-jobs" = 'false') and Paused ("printer-state" =
  'stopped', and "printer-state-reasons" = 'paused').  Then the
  operator issues Enable-Printer and Resume-Printer when want to
  restore normal operation.  The client can automatically issues these
  operations depending on GUI options.
  Advantages:  This is the simplest to implement, allows new states to
  be added without changing the Restart-Printer operation, and can have
  the same GUI interface as b:

  b. Add a REQUIRED operation attribute to Restart-Printer, something
  like "printer-condition" with values: 'disabled-and-paused',
  'enabled-and-paused', and 'enabled-and-idle'.

  c. Have Restart-Printer restore the enable/disable and paused/idle
  state to what it was when the Shutdown-Printer was issued.  The
  operation has to plan ahead at Shutdown-Printer time.

6. ISSUE:  Perhaps only Restart should work when a printer is shut down,
  not Get-Printer-Attributes?

  Suggested resolution:  We disagreed.  Get-Printer-Attributes must
  also work, so that a user can determine that the printer exists and
  find out that is it shutdown, why, and/or when it might come back up
  by querying the "printer-message-from-operator."

7. Tables for Set-Printer-Attributes and Set-Job-Attributes operations:
  Change all occurrences of "MUST NOT if supported" to "MUST NOT"

8. In the tables that show what attributes are settable for Set-Printer-
  Attributes and Set-Job-Attributes operations: should the table be
  replaced with a list the attributes that are REQUIRED to be read-
  only.  Perhaps there is an attribute that lists all settable
  attributes.

  ISSUE:  Can we add just one Printer Description attribute: "settable-
  attributes" or do we need a "printer-settable-attributes" and a "job-
  settable-attributes" Printer Description attributes?  What if the
  Interpreter and/or the Document object become real objects, would we
  need to add "interpreter-settable-attributes" and "document-settable-
  attributes" Printer Description attributes?

9. ISSUE:  Do "operations-supported" and "versions-supported" reflect
  software support or does the software examine the administratively
  set values to determine behavior. That is, are they read-only or
  read/write?

  Suggested resolution:  They are not included in the REQUIRED to be
  read-only list in the spec.  Therefore, implementer's are free to
  make them either read-only, meaning that they reflect the
  implementation and the client is unable to change via the protocol,
  or may make them be read-write, meaning that the client can change
  the behavior of the system using the protocol.  In the latter case,
  these attributes would be included in the new "printer-settable-
  attributes" Printer Description attribute.

  In order to allow the client to determine the values for the settable
  attributes that are supported by the implementation, as opposed to
  the current settings, it was suggested to add an operation attribute
  that allows the client to get the factory defaults, as opposed to the
  current setting, for the settable attributes.  If the "factory-
  defaults" (boolean) is supplied with a 'true' value, the factory
  defaults are returned, instead of the current values, for any
  requested settable attribute.

10.  Fidelity should go away for the set operation.  The set operation
  should be atomic.

11.  Set-Printer-Attributes operation:  The "document-format" operation
  attribute does have issues that were left unresolved.  Issue of how
  to resolve with attributes that do and don't vary with regard to
  format. For example if I set n-up and media for a format of
  PostScript and then Get-Printer-Attributes with a document format of
  text, have I changed the values of n-up and media, or just n-up
  because its value depends on the format but not media which doesn't.
  The document format is a limited version of constraints.

  ISSUE:  Do we continue the error with Get-Printer-Attributes by
  adding "document-format" to Set-Printer-Attributes or do we
  acknowledge that an attribute holds all values, but some may be
  constrained by constraints which are another attribute to set.

  Suggested solution:  Add an Interpreter object to the IPP Object
  model.  Those attributes that can have values depending on the
  interpreter, are modeled as Interpreter object attributes, instead of
  Printer attributes.  Those attributes that are the same for all
  interpreters, continue as Printer attributes.  In the Get-Printer-
  Attributes and Set-Printer-Attributes, the "document-format"
  operation attribute becomes part of the target specification for
  those attributes that are Interpreter attributes.  Implementations
  that have multiple interpreters, but don't have different values when
  validating jobs, would have a single Interpreter object that
  represents all interpreters.

  ISSUE:  Do we need a way to get and/or set the "xxx" attribute for
  all Interpreter objects in one Get-Printer-Attributes or Set-Printer-
  Attributes operation?  Or is it sufficient for a client to provide
  the equivalent functionality by stepping through all the values of
  the "document-formats-supported" with repeating the Get or Set
  operation?

12.  Keep unsupported values rules for Set-Job-Attributes consistent to
  Create-Job rules instead of new ones with new 'read-only' out-of-band
  value

13.  ISSUE:  Make stronger what operations do with regard to other
  protocols, e.g., disable should disable queue for other protocols
  too. People are not unanimous on this. Some believe that admin
  operation affect only the IPP channel; other believe it affect the
  entire device and thus other protocols "feel" the change.

  Suggested solution: While we agreed to RECOMMEND that IPP control
  other protocols, we also think it would help a lot to add a Printer
  Description attribute that indicates whether Printer operations
  affect other protocols or not.  This attribute would not be indicated
  as REQUIRED to be read-only, so that some implementer's could even
  allow System Administrator's to use the Set-Printer-Attributes
  operation to change whether these operations do or don't affect other
  protocols.

14.  ISSUE:  Is IPP intended for printer management. The issue is still
  undetermined?

15.  Shutdown-Printer operation's behavior should perhaps be left more
  implementation dependent with respect to Pause/Resume of job. It is
  hard for us to prescribe some printer dependent behavior as to
  whether a job can be resumed after a "now" type of shutdown.

16.  ISSUE 6 (Shutdown-Printer operation) and ISSUE 11 (Pause-Job
  operation):  The "synchronize" attribute: it is not clear why this
  would ever be false.  Ok to get rid of from the Shutdown-Printer and
  Pause-Job operations?

17.  ISSUE:  It isn't clear which type of checkpointing is being
  suggested for synchronize: checkpoint a stream or checkpoint in a job
  that is on a disk file in the printer.

18.  ISSUE 9 (Pause-Job operation), ISSUE 12 (Pause-Current-Job
  operation), and ISSUE 13 (Resume-Job operation):  The 'processing-
  stopped' state seems like the right job state for Pause-Job and
  Pause-Current-Job, rather than 'pending-held'.

19.  Do we really need Pause-Current-Job. Most people felt that Pause-
  Job was sufficient.

20.  Promote-Job seems to have no support. No one can see a reason.
  Also, it would seem that a GUI would want a drag and drop interface
  that would allow a job to be move to any position in a queue. This
  implies  that we must define a model for how a queue is ordered and
  what moving jobs does to the ordering.  For example a queue might be
  order by time of arrival, but the "move" operation would disrupt this
  temporarily. It would not change the fact that arriving jobs would
  still go to the end of the queue.

  We disagreed with removing Promote-Job.  We also agreed that the Get-
  Jobs operation must return the promoted job(s) first, since jobs are
  returned in the "expected time to complete" order.  In addition we
  agreed that a Printer can have more than one job in the promoted
  condition at a time, even though the Promote-Job operation only
  accepts one "job-id" at a time.  So if an implementation does have
  job queues, then the job is moved to the front of the queue.
  Therefore, subsequent Promote-Job operations before the previously
  promoted job started processing would just go in front of the
  previously promoted job.  The trick will be to specify these
  semantics in such a way as to not require a queue, since that is
  implementation dependent.

21.  ISSUE:  Does we really need a Space-Current-Job. This seems very
  specific to roll-fed printers.

  Suggested resolution:  No.  But do add a REQUIRED "job-id" operation
  attribute that a client MAY supply.  If supplied, then the job-id
  must match the current job or the one that still has paper in the
  paper path.  Printers that implement Space-Printer will also have a
  notion of what job is in the paper path, even though the job has
  finished marking.  Remember that the job is supposed to transition to
  the 'completed' state when "all of the job media sheets have been
  successfully stacked in the appropriate output bin(s).

22.  ISSUE:  Is Space-Current-Job reasonable to do in the 'processing'
  state when paper is still moving?

  Suggested resolution:  This is now moot, since Space-Current-Job is
  to be removed.

23.  ISSUE:  In the 'processing-stopped' state, is there a "current"
  job?

  Suggested resolution:  This is now moot, since Space-Current-Job is
  to be removed.

24.  Should be Space-Job with job-id if in spec at all.  Space-Current-
  Job is not to be in the spec at all.

The following numbered ISSUES were not addressed in the notes, so I've
copied them here so that we have one set of issues and agreements:

25.  ISSUE 2:  In the Reset-Printer operation, is the "non-process-run-
  out" operation attribute really needed at all or can the default
  behavior for Reset-Printer be defined to be to perform non-process
  run out (for continuous and cut sheet printers)?

26.  ISSUE 3:  In the Restart-Printer operation, is the "non-process-
  run-out" operation attribute really needed at all or can the default
  behavior for Restart-Printer be defined to be to perform non-process
  run out (for continuous and cut sheet printers)?

27.  ISSUE 4:  In the Space-Printer operation, is the "non-process-run-
  out" operation attribute really needed at all or can the default
  behavior for Space-Printer be defined to be to perform non-process
  run out (for continuous and cut sheet printers)?

28.  ISSUE 5:  Is the Shutdown-Printer operation, it the "non-process-
  run-out" operation attribute really needed at all or can the default
  behavior for Shutdown-Printer be defined to be to perform non-process
  run out (for continuous and cut sheet printers)?

29.  ISSUE 7:  On Shutdown-Printer with "when" = 'now', is the current
  job automatically restarted when the Printer is restarted?  Or does
  some client have to issue a Restart-Job operation?

30.  ISSUE 8:  On Cancel-Current-Job, why isn't non-process-run-out
  automatic on a continuous form printer?  When would an operator want
  to cancel the job and NOT run out the last sheets.?  It would be
  simpler to require process-run-out when canceling the current job
  (for continuous and cut sheet printers).

31.  ISSUE 10:  For the Pause-Job operation, is the "non-process-run-
  out" operation attribute really needed at all or can the default
  behavior for Pause-Job be defined to be to perform non-process run
  out (for continuous and cut sheet printers)?




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