Does SOAP support canceling a call?

Question

When using the SOAP protocol, is it possible to cancel a pending remote function call using SOAP?

I see three different situations:

• A) Making a request to a service that takes a long time to complete. For example, when copying directory containing a lot of files, can the file copy loop be canceled?

• B) Making a request that returns a long list. For example, when querying a big in-memory list of user names, can the transmission of this list-response be canceled?

• C) Canceling a call that is still on the internal call queue; in other words, before the server has begun processing it. This can happen when issuing a lot of asynchronous calls in a short time.

Answer 1

From the client's point of view, cancelling a synchronous (request-response) SOAP call is the same as for any other HTTP call - just disconnect and stop listening for the response. A well written server will check whether the client is still connected before proceeding with lengthy operations (e.g. in .NET the server would check IsClientConnected) and should cancel the operation if not.

One-way calls cannot be cancelled in this manner however, because you've already sent the payload and disconnected. Cancellation of one-way calls would require an explicit call to some sort of cancellation method on the SOAP service, which it would have to explicitly support.