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

It seems to me that there's a relationship to issue 025 (WRT multiple 
actions); if a message is allowed to have multiple action values, it's 
clear that there's not a simple, mechanistic relationship to the 
message content. Of course, the converse doesn't necessarily follow, if 
we decide to limit messages to a single action.

Cheers,

On Dec 21, 2004, at 6:13 AM, 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-
>
>
>
>
>

--
Mark Nottingham   Principal Technologist
Office of the CTO   BEA Systems

Received on Saturday, 1 January 2005 23:56:15 UTC