Taking a look at the proposed WSDL 2.0 spec you will see the following eight Message Exchange Patterns defined in the Part 2: Adjuncts document:
- In-Only
- Robust In-Only
- In-Out
- In-Optional-Out
- Out-Only
- Robust Out-Only
- Out-In
- Out-Optional-In
With some thought you can quickly surmise the behavior of each pattern, but applicability of the outbound patterns may not be readily understood. Indeed, their use is not intuitive but they do allow for some pretty important scenarios.
Let’s discuss Robust Out-Only how it may be applied. This MEP uses the Message Triggers Fault behavior. This means that for any node that generates a fault after receiving a message, the fault is sent to the message sender.
WSDL 2.0 defines two other fault propagation behaviors called Fault Replaces Message and No Faults not discussed in this post. As I stated before, the out-bound patterns are not obvious in their applicability and most certainly generate a number of questions. However, large enterprises that face the challenge of data subscribers and dynamic composability of services may find significant value here. This specific pattern may be implemented concretely as pub-sub service. A potential scenario may include wiring up a new packaged application to existing enterprise applications subscribing to published events. Using this scenario, the dev team would see that the new package exposed one or more Robust Out-Only services and would take the WSDL to define a service implementation for the packaged application to invoke. The packaged application would be notified of subscriber errors allowing corrective actions to occur.
By defining these MEPs as part of WSDL, the tools developed for the specification will certainly eliminate quite a bit of effort from developing more complex services and coordinating their interactions.
-CP
I finished Ghost Recon Advanced Warfighter on Sunday morning on Normal difficulty. Honestly, it felt a little easy and I finished rather comfortably in 7 days with me being away from my 360 during the week while travelling. I’ll kick up the difficulty and see what happens. For the record, this game still rocks and I thoroughly enjoy the strategy aspects of the game.
-CP