[standards-jig] JEP-0024: Publish/Subscribe - Topic based messaging

DJ Adams dj.adams at pobox.com
Mon May 13 08:51:54 UTC 2002


On Fri, May 10, 2002 at 09:34:14PM +0100, Dave Turner wrote:

> Yep, I guess that would work if by browsing you mean the subscriber browsing
> the broker by some given topic.  One thing that I think is very important is
> for the subscribers to be completely independant of the publishers.

Well, I don't think they can be completely independent; in (at least) most
of the cases that Piers and I had (have) in mind, the subscriber will want
to subscribe to a subject or subjects from specific publishers. The fact 
that the data is pushed by a 3rd (independent) party is IMHO unrelated to
the relationship between the subscriber and the publisher.

> I think that browsing publishers goes against the idea of pub/sub messaging.

:-) I think this is an example of why pubsub is such an interesting and
well-discussed topic; I don't think this at all.

> Afterall, by putting logic into the subscribers to request specific data from
> a specific publisher, aren't you just developing another protocol?

Well yes. Browsing (e.g. to discover what publishers might publish, and 
where they might publish it), is not pub/sub. That's not to say that a
browsing mechanism, or a discovery mechanism (UDDI/WSDL anyone?) for, er,
publications (for want of a better word) isn't useful. It is just separate
from pubsub itself. 

There are, as we've seen, other opinions on this. This is just my own.

dj




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