Web service and transactional guarantees

Question

How do you integrate applications via web services and deal with technical errors like connectivity errors for web service calls which change state?

E.g. when the network connection gets interrupted during a web service call, how does the client know whether the web services has processed its action or not?

Can this issue be solved at the business layer only (e.g. to query a previous call state) or are you aware of some nice frameworks/best practices which can help wrapping transactional guarantees around a web service?

Answer 1

Implementing it all by yourself with some kind of transactional context tracked in the business layer is always an option. You can use some compensation mechanisms to ensure transactions are rolled back if needed, but you'll need to:

• have the information on transactions persisted somewhere
• use transaction correlation IDs, so you can query when the response has been lost (having correlation IDs is good idea anyway)
• implement the operations needed to read/write/rollback, etc, so it might make your services a bit more complex

Another option I can think of is If you're using SOAP you can go for asynchronous communication and look for some stack implementing WS-Coordination, WS-AtomicTransaction and WS-BusinessActivity specifications, then decide for yourself if it is a good idea in your context or not. For example, I think Axis2 supports these, but of course eventually it depends on technologies and stack you use.

From the article above:

WS-AtomicTransaction defines a coordination type that is most useful for handling system-generated exceptions, such as an incomplete write operation or a process terminating abnormally.

Below are the types of 2-Phase Commit that it implements.

Hope this helps!