W3C home > Mailing lists > Public > public-ws-addressing@w3.org > January 2005

Re: Issue i017 - Purpose of the Action property -- my action item

From: Anish Karmarkar <Anish.Karmarkar@oracle.com>
Date: Mon, 10 Jan 2005 11:35:20 -0800
Message-ID: <41E2D8F8.1010103@oracle.com>
To: tim@mindreef.com
CC: public-ws-addressing@w3.org

Tim Ewald wrote:
>>1) The [action] property is supposed to uniquely identify the 
>>semantics implied by the message. Since the value of this 
>>property is fixed by the WSDL description (either through the 
>>defaulting mechanism or through the use of wsa:Action 
>>attribute), this value is really per message type within an 
>>MEP/operation/transmission primitive. Note that there are 
>>semantics associated with the MEP/operation grouping within 
>>an interface/portType as well as semantics associated with 
>>the individual input/output/fault message defined in WSDL. 
>>Why is it necessary to provide a mechanism, specifically the 
>>wsa:Action attribute, which overrides the default (where the 
>>default algorithm does produce a unique value)? What is the 
>>usecase for this? At the very least identical
>>(wsa:Action) attribute values should be disallowed, otherwise 
>>the [action] property will not uniquely identify the 
>>semantics implied by the message (type).
> 
> 
> By overriding the default action URI, a service can use well-known
> messages/actions that can be consumed by clients in a portType-independent
> way. For instance, consider WS-MetadataExchange, which has a well-known
> message/action to get metadata from a service. I want my service to expose
> that behavior to a clients without the consumer having to know what my
> portType is (it won't know until it gets my service's metadata). If only
> default actions are allowed, this model for generic behaviors will not be
> supported UNLESS a service described in WSDL 1.1 implements multiple ports
> (one for WS-MEX and one for its own interface) or in WSDL 2.0 derives from
> multiple interfaces.
> 
> Tim-
> 
> 

I agree that allowing one to override default action makes sense. 
Jonathan has made a similar argument that is also very convincing [1].

Also, this is an issue only if the WSDL is know (and used). If the 
portType is unknown (and therefore WSDL is not known and may not even 
exist) and an operation is being invoked on the service then this issue 
does not arise.

-Anish
--

[1] 
http://lists.w3.org/Archives/Public/public-ws-addressing/2004Dec/0173.html
Received on Monday, 10 January 2005 19:36:34 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 2 June 2009 18:35:01 GMT