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Re: D-AG0019 [RE: D-AG0007.1- defining reliable and stable WS ]

From: Mark Baker <distobj@acm.org>
Date: Wed, 3 Apr 2002 22:09:04 -0500
To: www-ws-arch@w3.org
Message-ID: <20020403220904.C23332@www.markbaker.ca>
On Wed, Apr 03, 2002 at 05:40:21PM -0500, Hugo Haas wrote:
> HTTP gives you (1) and (2) for free, and even more: removed resources,
> temporarily and permanently moved resources, etc. I think that all
> are desirable, and I think that it is where the goal comes from.

Hugo's right.  I believe that all of those features are useful for
anything with a URI, if it either is resolvable now, or may be
resolvable in the future.

"A priori" means;

   "Made before or without examination"
    -- http://www.dictionary.com/search?q=a+priori

To me, that means that before anybody even discovers the WSDL to find
out what the specific interface is about, that there exists a
pre-specified interface that can be used to bootstrap the richer
stuff on top.

So I think that the response codes like the ones Hugo mentions above
are part of this interface.  I also believe that a GET-like operation
is part of this interface, as I previously described with my WSDL-over-
GET example.  IMHO, our charter requires that we address how far we
can go with this a priori specified interface.

So perhaps there's enough here to warrant a new goal, or perhaps
a subgoal of 19.  Something like;

  "defines a generic interface for all Web services that provides
   sufficient a priori agreement to permit distributed extensibility
   without third party agreement"

> The question is how that will be supported by other protocols, e.g. if
> my service is identified by the <mailto:myservice@mydomain.example>.
> This is why I think that we should recommend such practices, when
> applicable (in HTTP's case, it definitely is).

An interesting thing about HTTP is that, unlike other protocols, it can
take any URI, not just a HTTP URI.  The reason this is so, was recently
described by the TAG;

  "In any context that allows a URI, any URI may be used. It is an error
   to say that only URIs of a specific scheme are allowed in a certain
     -- http://www.w3.org/2001/tag/doc/identify.html

which is also found in Tim's writings;

  "Any place I can use a URI I can use any URI."
     -- http://www.w3.org/DesignIssues/UI.html

This means you can do this with HTTP;

GET mailto:myservice@mydomain.example HTTP/1.1


POST mailto:myservice@mydomain.example HTTP/1.1
[message goes here]

etc..  You just need an email/HTTP intermediary.

Mark Baker, Chief Science Officer, Planetfred, Inc.
Ottawa, Ontario, CANADA.      mbaker@planetfred.com
http://www.markbaker.ca   http://www.planetfred.com
Received on Wednesday, 3 April 2002 22:10:06 UTC

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