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Re: another approach to status codes, etc. in HTTP binding

From: Mark Baker <distobj@acm.org>
Date: Thu, 19 Jul 2001 23:42:31 -0400
Message-ID: <3B57A8A7.87CF86DF@acm.org>
To: Rich Salz <rsalz@zolera.com>
CC: xml-dist-app@w3.org
Rich,

(Jacek, I mean this to answer your questions as well)

Rich Salz wrote:
> 
> > I was using PUT and POST as an *example*.
> 
> Okay, then please dsecribe an HTTP application semantic that is useful
> to SOAP above and beyond transport.

It's not that HTTP's application semantics are useful to SOAP, it's that
SOAP is useful to HTTP's application semantics.  So I guess the answer
to your question is "All of them usable with POST".

Tunneling hides these semantics.  But since no communication between
parties can occur without them, they have to be defined someplace.  The
RPC use of SOAP "solves" this problem by encouraging every interface to
define its own.  e.g. (from the SOAP spec);

<SOAP-ENV:Envelope
  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
   <SOAP-ENV:Body>
    <m:GetLastTradePrice xmlns:m="Some-URI">
        <symbol>DIS</symbol>
    </m:GetLastTradePrice>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

"GetLastTradePrice" is the application semantic in use here.  It
presumably means "get the last trade price" (but who really knows, as
it's not specified anyplace).

That is one use of SOAP, and fits very well with the tunneling view of
the protocol binding.  It is also useful when SOAP is bound to a
transport protocol instead of an application protocol.

Another use of SOAP is that it adopt the semantics of the application
protocol to which it is bound.

Take the example of me wanting to add a contact to my contact list. 
Without SOAP, I could do this by POSTing an xCard to, say,
/user/mbaker/contacts.  But suppose I want to do it in the context of a
transaction.  I could do exactly the same thing - POST the xCard to
/user/mbaker/contacts - but I could wrap the xCard in a SOAP envelope
and specify in the header the use of ebXML or Biztalk transactions.  The
meaning of "insert this into that" (POST) remains, but it's been
extended with transactional semantics.

Anyhow, I'm going out of town for a week so won't be able to follow up
as frequently as I have been.  Don't anybody take that to mean that I'm
backing down! 8-)

MB
Received on Thursday, 19 July 2001 23:43:05 GMT

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