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RE: Label for Top Node of "triangle diagram"

From: David Booth <dbooth@w3.org>
Date: Wed, 02 Oct 2002 17:37:48 -0400
Message-Id: <>
To: www-ws-arch@w3.org
Cc: Dave Hollander <dmh@contivo.com>, Ricky Ho <riho@cisco.com>

>[Ricky] It has to be "exposed" in some way. But it doesn't need to be a 
>"central place". Think about the Gnutella model.
><daveh> Nope, not a central place, but where and how? There is no implicit 
>hypertext network to crawl, so how are service providers to assure that 
>their service is found? No matter what we say, the providers and discovery 
>service operators will find a way. Sometimes they will be satisfied with 
>an more organic like Gnutella, other times they will insist on a more 
>regimented model like MP3.com.

Yes!  I agree completely.  There is no need to have a "central place" for 
advertising/discovery of Web Service descriptions, and our architecture 
should not imply that any such thing is required.

Then where and how can a Client find a Service?  Well, the "where" depends 
on the "how".  In the general case, the "where" is the Web of all 
electronically accessible data.  If the "how" is "by a UDDI request", then 
the "where" is easy to identify: It's a particular UDDI registry.  But if 
the "how" is "by a Gnutella search", then "where" is not so easy to 
identify, nor is it so relevant.  The important thing is just that Gnutella 
finds the data you want -- somewhere on the Web -- and gives it to you.

In short, there are many ways that a Client might find a Service, and the 
Services that the Client finds may depend on the mechanisms that it uses to 
perform the discovery.  This is a feature, not a bug.  It means freedom of 
choice.  It's one of the nice things about the Web.

Of course, the downside is that you will never be sure that you have 
discovered ALL of the available Web Services.  Unfortunately, that's life, 
and it's okay.  It is inherent in the Web's open-world model.  New Services 
can come and go as "dark matter" unbeknownst to you.  And if you don't like 
dealing with the uncertainty that that implies, then you can just sign up 
for a single, big, centralized discovery service and pretend that nothing 
else exists.   Depending on what you want to do, that may be a very 
reasonable approach.  It is analogous to shopping only at a single, big, 
centralized department store instead of dealing with a plethora of 
merchants scattered throughout an entire city.  Sometimes it makes 
sense.  But our architecture shouldn't imply that we only support the 
centralized model.

David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Wednesday, 2 October 2002 18:18:28 UTC

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