WSDL op FAQ

[Jacques Durand <JDurand@us.fujitsu.com>]

Title: WSDL op FAQ

Tom keeps reminding me over a lingering action item for the FAQ,
about WSDL operations support.

Here is my proposal:

Q: How does the WS-Reliability protocol relate to WSDL operation types?

WS-Reliability has been designed to support One-Way and Request-Response operations.
The two following requirements are observed by WS-Reliability:

1- An implementation of WS-Reliability is not supposed to be aware of the type
of WSDL operation associated with the messages it is processing.
2- The RM protocol specified is compatible with current WS-I profiles.

One-Way operations: All RM features specified apply to these operations,
with the following restriction: In order to comply with current WS-I profiles,
the "Response" reply pattern must not be used with these operations.

Request-Response operations: These are often supported in a synchronous way by SOAP implementations, and in general this gives to the application a level of control that reduces the benefits of RM features. Some reliability features clearly are not much relevant (like Ordered Delivery, given that the application layer itself has control on the sequencing). The application can also be certain that a delivery occurred, when it receives the response.

Although the RM features defined may still be used, the Guaranteed Delivery protocol defined here does not apply to the "response" leg of Request-Response operations because its transport-synchronous nature (as required by WS-I profiles) requires special handling left out of 1.0.

Because an implementation is not required to distinguish messages based on their associated WSDL operation type, enforcing the above restrictions (with the exception of the "response" leg) depends on the user layer, e.g. messages have to be sent under the reliability agreement that is appropriate to their WSDL operation type.