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mandatory action

From: Jacek Kopecky <jacek.kopecky@deri.org>
Date: Tue, 03 May 2005 16:45:09 +0200
To: public-ws-addressing-comments@w3.org
Message-Id: <1115131509.3326.137.camel@Kalb>

Hi,

as an LC comment for WS-Addressing, I'd like to voice my disagreement
with the decision in WS-Addressing that action IRI is mandatory in all
WS-Addressing-compliant messages.

The spec says "It is RECOMMENDED that the value of the [action] property
is an IRI identifying an input, output, or fault message within a WSDL
port type. An action may be explicitly or implicitly associated with the
corresponding WSDL definition."

This shows that WS-Addressing ascribes semantics to WSDL operations,
which the WSDL specification doesn't currently warrant. I don't object
to this particular assumption, but you should be aware that other WSDL
users may have a different view.

WSDL 2 contains an Operation Name Mapping Requirement [1] that assumes
that the bodies of the messages in a single WSDL interface unambiguously
identify the operation, or that an extension is present that enables the
receiver of a message to identify the intended operation, and by
extension (using the above assumption) identify the intended semantics. 

Therefore, if [action] identifies the input, output or fault within a
WSDL interface, as RECOMMENDED, and if the default action pattern
currently present in the WS-Addressing WSDL Binding draft [2] is used,
and in fact if WS-Addressing action is not the mechanism for fulfilling
the Operation Name Mapping Requirement, then [action] is redundant.

That's a lot of ifs but given the current ways of generating WSDL that
are known to me it seems like a very common scenario. 

If I was implementing a Web Services stack, I'd like it to allow the use
of WS-Addressing, but not require it. Therefore I'd choose to identify
the intended semantics of messages in general from their bodies.
Therefore WSDLs generated by this tooling would either not specify
action (and thus recommend the use of the default action pattern) or
simply put the same action, for example "http://example.com/dwim", on
all messages, and by default ignore the action property in incoming
messages.

So I basically don't see a reason for [action] to be mandatory in
WS-Addressing.

I propose two options for a solution:

1) Factor [action] out of WS-Addressing, to a specification (called
WS-Semantics?) that would be optionally combinable with WS-Addressing,

2) or make [action] optional, i.e. MAY-strength,

and in both cases [action] should be formulated as an extension or
feature to be used in WSDL 2 to fulfill the Operation Name Mapping
Requirement, if the message bodies don't suffice.

Best regards,

                   Jacek Kopecky

                   Ph.D. student researcher
                   Digital Enterprise Research Institute
                   University of Innsbruck
                   http://www.deri.org/


[1] http://www.w3.org/TR/2004/WD-wsdl20-20040803/#Interface_OperationName
[2] http://www.w3.org/TR/2005/WD-ws-addr-wsdl-20050215/#_Toc77464322
Received on Tuesday, 3 May 2005 14:45:19 GMT

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