In summarizing the significant conformance requirement increases that we
agreed to today in the review of the IPP Document Object spec review, I
forgot two more:
1. Add a REQUIRED way to the Get-Documents operation for the client to get
the Documents following the limit requested in a previous request.
So add the "start-after-document-number" (integer (0:MAX)) Operation
attribute.
2. Add a REQUIRED way to the Get-Jobs operation for the client to get the
Jobs following the limit requested in a previous request.
So add the "start-after-job-id" (integer (0:MAX)) Operation attribute.
Please send any comments on these additions by Friday, May 2, COB.
Here are the complete proposed text for these attributes and the updated
"limit" Operation attribute:
1.1 Get-Jobs ([rfc2911] section 3.2.6)
This REQUIRED Job operation returns requested attributes of either completed
or not completed Jobs. The following (new) "start-after-job-id"
(integer(0:MAX)) Operation attribute is defined which in combination with
the "limit" operation attribute ([rfc2911] section 3.2.6) permits a client
to request selected ranges of jobs:
1.1.1 "limit" (integer(1:MAX)):
The client OPTIONALLY supplies this Operation attribute.
The Printer MUST support this Operation attribute. It is an integer value
that determines the maximum number of Jobs that a client will receive from
the Printer even if "which-jobs" or "my-jobs" constrain which jobs are
returned. The limit is a "stateless limit" in that if the value supplied by
the client is 'N', then only the first 'N' jobs are returned in the Get-Jobs
Response. If the client does not supply the "limit" attribute, the Printer
responds with all applicable Jobs. However, if the client also supplies
the "start-after-job-id" Operation attribute (section 4.2.2) with a value
'M', the Printer returns the N Jobs starting with the Job following the one
with "job-id" = 'M'.
1.1.2 "start-after-job-id" (integer(0:MAX)):
The client OPTIONALLY supplies this Operation attribute.
The Printer MUST support this Operation attribute. If the client supplies
this attribute with a job-id value 'M', the Printer MUST return Jobs
starting with the Job that is after the one with "job-id" = 'M'. If the
client does not supply this attribute, the Printer assumes a '0' value which
causes the Printer to return any Jobs with any "job-id" that meet the
requested criteria (specified by "which-jobs" and/or "my-jobs", etc.). When
the client steps through the jobs N at a time, the client MUST set the
"start-after-job-id" attribute from the "job-id' of the last Job returned in
a previous Get-Jobs response (rather than just adding 'N', since Printers
MAY assign job-ids out or order).
The client can detect when there are no more jobs when the
Printer returns fewer jobs than requested by the "limit" Operation attribute
('N'). In the case when the last number of jobs returned is exactly N jobs,
the client will make an extra request and receive no jobs back (still with a
'successful-ok' success code). However, this case still meets the criteria
for no more Jobs since the number of Jobs returned (0) is less than
"limit"..
Note when the client steps through the Jobs supplying the
"limit" and "start-after-job-id" Operation attributes in successive Get-Jobs
requests, there are some race conditions which the client implementer needs
to take into account:
* For 'non-completed' Jobs (see [rfc2911]
section 3.2.6.2), the Printer MUST return the Jobs in the order of the
"expected time to complete" with the first expected to complete being
returned first, etc. Because some Printers MAY: (1) process jobs out of
order received, and/or (2) assign "job-id" in a non-monotonically increasing
manner, occasionally a race condition MAY cause some jobs not be returned
and some jobs MAY be returned more than once. The only way for a client to
eliminate this race condition for 'not-completed' Jobs is to request all
Jobs by supplying neither the "limit" nor the "start-after-job-id" Operation
attribute.
* For 'completed' jobs (see [rfc2911] section
3.2.6.2), the Printer MUST return the jobs in the order of "newest to
oldest" to complete. Therefore, no jobs will be missed and/or doubly
returned.
1.2 Get-Documents Operation
This REQUIRED Job operation allows a client to retrieve the list of Document
objects belonging to the target Job object. The client MAY also supply a
list of Document attribute names and/or attribute group names. A group of
Document object attributes will be returned for each Document object in the
Job.
This operation is similar to the Get-Document-Attributes operation (see
section 3.5), except that this Get-Documents operation returns attributes
from all Document objects contained in the Job object, instead of from a
single selected Document object in the Job object. As with the
Get-Document-Attributes operation the Printer MUST only return attributes
that were submitted by a client when the Document object was created by the
Create-Document, Send-Document, or Send-URI operations and possibly modified
by the Set-Document-Attributes operation (see section 3.7).
1.2.1 Get-Documents Request
The client submits the Get-Documents request to a Printer. The
Get-Documents is similar to the Get-Jobs operations (see [rfc2911] section
3.2.6) except that there are no equivalents to the "which-jobs" and
"my-jobs" Operation attributes.
The following groups of attributes are part of the Get-Documents 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:
Either (1) the "printer-uri" (uri) plus "job-id"
(integer(1:MAX)) or (2) the "job-uri" (uri) Operation attribute(s) which
define the target Job object 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.
1.2.1.1 "limit" (integer(1:MAX)):
The client OPTIONALLY supplies this Operation attribute.
The Printer MUST support this Operation attribute. It is an integer value
that determines the maximum number of Documents that a client will receive
from the Printer. If the client supplies the "limit" attribute with a value
'N' and the "start-after-document-number" attribute with a value 'M', the
Printer returns the N Documents starting with the Document after the one
with "document-number" = 'M'. The limit is a "stateless limit" in that if
the value supplied by the client is 'N', then only the first 'N' Documents
are returned in the Get-Documents Response. If the client does not supply
the "limit" attribute, the Printer responds with all Documents in the Job.
However, if the client also supplies the "start-after-document-number"
Operation attribute (section 4.3.1.2) with a value 'M', the Printer returns
the N Documents starting with the Document following the one with
"document-number" = 'M'.
1.2.1.2 "start-after-document-number" (integer(0:MAX)):
The client OPTIONALLY supplies this Operation attribute.
The Printer MUST support this Operation attribute. If the client supplies
this attribute with a document-number value 'M', the Printer MUST return
Documents starting with the Document that is after the one with
"document-number" = 'M'. If the client does not supply this attribute, the
Printer assumes a '0' value which causes the Printer to return Documents
starting with "document-number" = '1' (which is the first document in the
Job).
Note: canceled Documents (see section 3.7) are still
returned, but deleted Documents (see section 3.8) are skipped over, since
they don't exist (leaving gaps in the "document-number" sequence).
Please send any comments on these additions by Friday, May 2, COB.
Thanks,
Tom