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Re: Proposal for Describing Web Services that Refer to Other Web Services: R085

From: Sanjiva Weerawarana <sanjiva@watson.ibm.com>
Date: Tue, 29 Apr 2003 01:00:42 +0600
Message-ID: <04d601c30db8$a76762e0$31120209@lankabook2>
To: "Mark Baker" <distobj@acm.org>, "Amelia A. Lewis" <alewis@tibco.com>
Cc: <www-ws-desc@w3.org>

"Mark Baker" <distobj@acm.org> writes:
> >
> > TimBL's original proposal was for "universal" identifiers/locators.  The
IETF rejected that term, replacing it with "uniform".  They are uniform;
they are not universal.
> They're wrong, because it's absolutely trivial to test if they're
> universal; just try and identify something which cannot have a URI.  It
> would only take *one* example to disprove the universal hypothesis, yet
> nobody's been able to find one yet.
> Do you really doubt that any string can identify anything?  How
> would language have evolved if that weren't the case?  "Oh, you can't
> use that word for that concept, sorry - our words can only identify
> [fill-in-the-blank]".

I'm sure you're right that one can define an encoding of any kind of
information as a string. If that were not true the whole single-tape
Turing machine stuff would be invalid. Oops.

I think we're missing the point of the discussion. What Arthur
proposed was a way for one to point to a URI in a message and say
"see that URI? That's not just a URI - it points to a Web service".
That's very RESTful and hopefully you like it Mark.

The second thing Arthur did is to say that there is this other
thing called WS-Addressing that some companies have developed
which they seem to like as a way to point to Web services. So his
proposal allows one to point to a piece of XML typed by a WS-Addressing
endpoint reference and say "see that endpoint refernce type thing?
That's not just a piece of XML; it points a Web service".

It seems to me that you're arguing against the 2nd part, right?
If so, the real argument is with those who created WS-Addressing
and endpoint references within them.

As I'm one of those, I can give some rationale (which you may or
may not agree with). Basically, I agree that we could've just
defined a new URI scheme instead (wsep:*). However, that would've
meant we have to define some funky rules to encode all the
stuff we want to contain in an endpoint reference: a URI for the
address, the WSDL type/service info, any "instance ID info", any
policies that may apply or any other data that the creator of
the reference would like to have you send back. Mathematically,
that's a trivial thing. Practically, that would've meant that we
would have to write a custom software to handle all this encoding /
decoding stuff.

Alternatively, we chose to define an XML Schema type and just make
each of the parts explicit. Why? We thought it was simpler to
use, read and to love.

Received on Monday, 28 April 2003 15:01:23 UTC

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