i017: Purpose of Action property

Issue i017 [1] is about the purpose of a non-default Action. I.e., the 
ability to specify the value of the [action] MIH using the wsa:Action 
attribute in WSDL.

WS-Addressing [2] submission say:

"
[action] : URI (mandatory)
     An identifier that uniquely (and opaquely) identifies the semantics 
implied by this message.

     It is RECOMMENDED that value of the [action] property is a URI 
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. Section 3.3 below describes the 
mechanisms of association. ...

"

WSDL groups messages into MEPs or operations or transmission primitives. 
There are semantics associated with the MEP grouping within an 
interface/portType as well as semantics associated with the individual 
input/output/fault messages. WS-Addressing does have rules (default) for 
the [action] MIH which uniquely identify the portType/interface/message 
and therefore the semantics. Given this, why is it necessary to provide 
another mechanism to provide a different value for the [action] MIH? Is 
there a usecase for this? Furthermore, there is no requirement that the 
wsa:Action attribute value within a portType/Interface be unique -- 
which means that potentially all the messages sent for all the 
operations within a portType/interface may have the same value for the 
[action] MIH. It seems like this should be disallowed as the [action] 
MIH is supposed to indicate the semantics of the message.

There is a operation name mapping requirement in WSDL 2.0 [3]. What is 
the relationship of [action] with this feature? They seem to do similar 
things (although the operation name mapping is an abstract feature). 
WS-Addressing should specify the relationship between the two, if any. 
Please note that during the WSD F2F held last week there was a 
discussion of defining default rules for operation name mapping which 
would uniquely identify not only the operation but also the message 
within an operation. This issue is still pending in WSD; waiting for an 
action/proposal to be done.

-Anish
--

[1] http://www.w3.org/2002/ws/addr/wd-issues/#i017
[2] http://www.w3.org/Submission/2004/SUBM-ws-addressing-20040810/
[3] http://www.w3.org/TR/2004/WD-wsdl20-20040803/#Interface_OperationName

Received on Monday, 15 November 2004 19:35:02 UTC