IPP Mail Archive: Re: IPP> Notification content

Re: IPP> Notification content

James Walker (walker@dazel.com)
Wed, 11 Mar 1998 15:16:50 -0600

Harry Lewis wrote:
>
> In Austin, I think we discussed the IPP notification requirement that any
> attribute may be requested during registration for a given event. I think the
> requirement stems from the notion that notification content should just "mimic"
> the response to a query. But this is probably unrealistic. A query/response is
> synchronous - during which, the "agent's" job is to gather the requested
> information and package the response. With notifications, you pre-register for
> asynchronous events. It would be a much greater burden on the agent, whether it
> be IPP, SNMP or whatever, to maintain, not only of who wants which
> notifications, but also what information they requested with each type of event!

IMHO, this is one of those areas where the requirements differ depending
upon whether we are talking about a host->device protocol, or the more
general client->server protocol.

In the case of a host->device protocol, I agree 100%... the host should
be able to register for specific event types, where the event associated
with each event type has some fixed, standardized content. This is
along the lines of what was discussed in the JMP meeting in Austin.

However, in the more general client->server case, I think that variable
content is an important requirement. Specifically, I think that it is
important that the notification be capable of holding enough information
such that the client does *not* have to go back and query the server to
get what it needs. Seeing as how we cannot mandate what information the
client should be interested in, this implies that we should allow the
client to specify its interest. Furthermore, if we are to allow vendors
to extend IPP, then the only way that clients can get at that extended
information in a notification is if we allow the client to ask for what
it wants.

one man's opinion...
...walker

--
Jim Walker <walker@dazel.com>
System Architect/DAZEL Wizard
DAZEL Corporation, Austin, TX