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Proposal: Uniqueness on the Wire Requirement for WSDL 2.0

From: Umit Yalcinalp <umit.yalcinalp@oracle.com>
Date: Mon, 20 Oct 2003 15:25:37 -0700
Message-ID: <3F9460E1.9060908@oracle.com>
To: WS Description List <www-ws-desc@w3.org>


Today, the operation name do not appear on the wire. The input and 
outputs are described with respect to messages exchanged and the 
operation name is just for tools and bindings to refer to. This brings 
up an interesting requirement for endpoints tobe able to correlate the 
input/output messages to operations that define these message exchanges. 
The wire signature for operations must be unambiguous.

There are three different ways of solving this problem that I can think of:

1. Require that operation names DO appear on the wire. This can be 
achieved by wrappering the name of the operation, as required for RPC 
style. This is actually NOT a real burden actually on the processors to 
unwrap the actual message and obtain the actual element that designates 
the input. The soap Body is treated similarly by the processors.

2.  Describe a header that contains the name of the operation and is 
REQUIRED as part of the envelope. Note that some implementations and 
platforms DO carry this information using soapAction and use this info 
for dispatching purposes.  However, this is very SOAP specific. Further, 
this is a bit different than specifying properties/features as this 
header MUST always be present for interoperability and for non SOAP/HTTP 
bindings to use it appropriately.

Of course, these two approaches indicate that the operation name MUST 
appear somewhere on the wire, either in the message or in the header :-). 

3.  I would like to bring one of the WS-I BP 1.0 rules into picture and 
propose that we have a similar requirement in the spec as the third 
option. See [1] Section 5.6.7, rule R2710. This rule is written with 
respect to WSDL 1.1, where the binding indicates how the message on the 
wire would be constructed/indicated.

In our current spec, however, the structure of the messages are already 
defined by input/output messages. So the binding has very little to do 
with this requirement. Instead the burden of defining wire signature for 
operations shifts to requiring interfaces to contain unique messages.

This can be achieved by requiring an interface not to use the same 
element as an input (or output) in more than one operation. This is in 
spirit the same requirement as stated in R2710. 

I propose a rule  to be added in section 3.1.3. along the lines of the 

"An element declaration MUST NOT be referenced from the body of input 
(or output) element information items of more than one  interface 
operation component children of an interface component"

If we are not going to have the operation name to appear on the wire, it 
is essential for us to add this rule to the spec.



[1] http://www.ws-i.org/Profiles/Basic/2003-08/BasicProfile-1.0a.htm

Umit Yalcinalp                                  
Consulting Member of Technical Staff
Phone: +1 650 607 6154                          
Email: umit.yalcinalp@oracle.com
Received on Monday, 20 October 2003 18:25:41 UTC

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