PMP> Multiple operations within a single IPP message?

PMP> Multiple operations within a single IPP message?

JK Martin jkm at underscore.com
Fri Jan 17 11:39:00 EST 1997


Regarding this issue, I agree 110% with Randy.  One should think
twice (or more) times before considering handling multiple operations
due to the state ramifications.


Perhaps we should try answering Randy's (paraphrased) question:


  "Why would a single operation per transaction be undesirable?"


Can anyone state any serious limitations?


	...jay


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Date: Fri, 17 Jan 1997 08:25:56 -0800
From: Randy Turner <rturner at sharplabs.com>
MIME-Version: 1.0
To: rdebry at us.ibm.com
CC: ipp at pwg.org
Subject: Re: IPP> IPP Requirements Scenarios
Content-Transfer-Encoding: 7bit


rdebry at us.ibm.com wrote:
> 
> Classification:
> Prologue:
> Epilogue:
> 
> The following notes are in response to Jay's comments
> 
> 1) You suggested replacing PUSH and PULL with
> 
>      The protocol must support these sources of client print data
>       - print data is a file
>       - print data is being generated on the fly by an application
>       - print data is referenced by a URL
> 
> Answer:  don't have a problem in stating the requirement this way. However,
> I'm not sure that we want to place getting a referenced file outside of the
> scope of IPP v1.0.  I'd like some other comments on this.
> 
> 2) With respect to the first print job submission scenario you asked,
>  "has it been decided that a single IPP transaction can contain more
> than one type of request?"
> Answer:  Herriot, Isaacson, Hastings and I agreed on this in early
> discussions of the first IPP draft.


If you have a protocol wherein multiple operations are specified, each
with a "state" dependency on the previous operation (meaning that the
sequence of operations is part of the overall "stateful" request) then
this could complicate things considerably; meaning, you might have to
include some type of two-phase commit operation to verify that all of
the operations in a particular transaction complete or none at all.


This may not have implications now if we have a very limited
transaction/request set, but we will no doubt be extending this in the
future. I'm not sure why a single request per transaction would be
overly limiting in a first implementation of IPP.


Randy




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