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Problem with HTTP verbs as WSDL operations

From: Jacek Kopecky <jacek@systinet.com>
Date: 05 Jun 2003 16:39:06 +0200
To: WS-Description WG <www-ws-desc@w3.org>
Cc: Mark Baker <distobj@acm.org>
Message-Id: <1054823946.13010.36.camel@localhost>

Hi all,

I've been vaguely following the discussion on issue 64 [1] and this
thought occurred to me:

HTTP (and other application protocols) defines an interface, something
like:

interface HTTP {
  MIMEHeaders head(URI, MIMEHeaders);
  MIMEMessage get(URI, MIMEHeaders);
  MIMEMessage post(URI, MIMEMessage);
  MIMEMessage put(URI, MIMEMessage);
}
MIMEMessage := MIMEHeaders + MIMEContent

This maps to a WSDL interface with four operations and MIME stuff as
parameter and return value types.

Now what everybody seems to expect to do is restricting this interface
and still presenting it as HTTP - in other words adding strong typing:

interface StockQuoteResource restricts HTTP {
  MIMEHeaders head(URI, MIMEHeaders);
  StockQuoteMessage get(URI, MIMEHeaders);
  // post and put not redefined as they will not be permitted anyway
}
StockQuoteMessage := MIMEHeaders + XML Schema element StockQuote

If that's correct, we may need to add the ability to actually redefine
(and maybe hide) parent interface's methods in a new interface. That
feels like building a full object-oriented IDL language.

If, on the other hand, REST's uniform interface principle means we
shouldn't restrict it, we won't be able to describe a StockQuoteResource
in WSDL and every HTTP resource described in WSDL would implement the
above-mentioned HTTP interface.

Personally, I would expect to be able to have a strongly-typed
description of my HTTP resources so that, while a browser would use the
full HTTP interface, programs could use an interface with more semantics
to it. But I can't think now of any simple way to have a strongly typed
WSDL interface that still shows its relation to the HTTP
application-protocol interface.

Does this make any sense? 8-)

                   Jacek Kopecky

                   Senior Architect
                   Systinet Corporation
                   http://www.systinet.com/

[1] http://www.w3.org/2002/ws/desc/2/06/issues.html#x64
Received on Thursday, 5 June 2003 11:05:53 GMT

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