Subject: IPP> PRO - Notifications

From: Carl-Uno Manros <[email-masked]>
Date: Tue, 3 Feb 1998 13:22:56 PST

At 10:51 AM 2/3/98 PST, you wrote:
>Has anybody noticed that IPP will be useless for notifications due to the
>asymmetry of the protocol? As currently constituted a printer cannot send an
>unsolicted message to anybody. 
>
>Was this discussed later on on the Thursday brainstorm?
>

Paul,

This has been extensively discussed in previous meetings and phone
conferences. We are aware of the fact that IPP is a client-server protocol
based on HTTP, which has some limitations. You can always find out about a
print job by asking the IPP server what happened to it (Hint - heard about
PUSH technology?). 

If we want to have a notification service that is initiated by the IPP
server, we will need a separate notification protocol, which could either
be unique for IPP notifications or more general to notify events from a
number of different services. Previous discussions seemed to favor the
letter approach, which is why we decided not to tackle it as part of IPP
V1.0. We may actually only need to specify a MIME type with the right kind
of content, which can be sent by email, FTP, HTTP or whatever transport is
available on the IPP client side.

Carl-Uno
Carl-Uno Manros
Principal Engineer - Advanced Printing Standards - Xerox Corporation
701 S. Aviation Blvd., El Segundo, CA, M/S: ESAE-231
Phone +1-310-333 8273, Fax +1-310-333 5514
Email: [email-masked]