> You all must pardon me if I am covering ground that has been covered
> before, but since I was not able to attend the IPP meetings last week
> my
> thinking may be a bit behind where everyone else is at.
>
> In reading through the minutes of the meeting and recent email on the
> discussion list, it seems to me that we may have invented more
> operations for IPP than we really need. It seems to me that we added
> CreateJob to allow a client to validate job attributes prior to
> sending
> all of the print data. The original send operation (which I think we
> are
> back to) simply transmits the print data. The deBry/Carter proposal
> to use multiple send Documents was not accepted. We are
> depending upon http chunking to allow the client to send the
> print data in pieces and upon tcp/ip to guarantee delivery.
> We added Validate and PrintJob to provide for the simple print case
> proposed by Microsoft. As I read the minutes and email it also seems
> that we generally agreed that well behaved clients would always know
> printer characteristics, either because the Printer has been
> "installed"
> on the desktop or the client has queried the capabilities of the
> printer.
>
> So as I see it, we are left with the following:
>
> CreateJob - used to validate the print job
> Validate - used to validate the print job
>
> SendDocument - its only value is to transmit the job data
> PrintJob - transmits the job data and the job attributes
>
> What am I missing? In the spirit of simplification, it appears to me
> that we
> could get rid of CreateJob and SendDocument. I see little value to
> these operations given the current set of proposals on the table.
> The
> only thing I see is that I save resending the job attributes in the
> sequence
> CreateJob, SendDocument over the sequence Validate, PrintJob. Since
> a well behaved client would know the capabilities of the Printer it
> would
> normally not be necessary to validate job attributes and PrintJob
> would almost always be the preferred method to use.
You are not considering the other advantages of the 'CreateJob'
operation. The 'Validate'
option only validates a set of attributes against what a particular
object supports. It has no relationship
to a job. Meaning that just because you send a 'Validate' request, does
not necessarily mean that a
print job is next in the sequence. The 'CreateJob' not only validates
attributes but also determines whether
or not resources can be applied NOW to processing a job with these
requirements. Also, 'CreateJob'
returns the URI for the job object created immediately so you have some
way to either do a 'GetAttributes'
or a 'Cancel' on the job if either one of these operations is required.
If you're looking to delete operations, 'Validate' would go before
'CreateJob' IMHO.
Randy
> Roger K deBry
> Senior Techncial Staff Member
> Architecture and Technology
> IBM Printing Systems
> email: rdebry@us.ibm.com
> phone: 1-303-924-4080