Are Axis2 generated stubs thread-safe?

Question

Are client stubs generated from WSDL by Axis2 thread-safe?

Of course, "thread-safe" isn't necessary a rigorously defined term, so I'm at least interested in the following:

Are different instances of the same stub class accessible concurrently by different threads, with the same effective behavior as single-threaded execution?

Is a single instance of the same stub class accessible concurrently by different threads, with the same effective behavior as the same calls interleaved in some arbitrary way in single-threaded execution?

You may also wish to use the terminology described here (and originating here) to discuss this more precisely.

Answer 1

These stubs are stateless allowing reuse of the stub instances. Can you please elaborate on the problem you are facing with Axis2. People usually recommend Xfire over Axis.

Answer 2

I'm not sure about axis2, but at least axis1 generates non-threadsafe client stubs. I got the impression pretty much every other SOAP client was non-threadsafe as well. If I remember correctly the issue was with the XML parsing library being used in a non-threadsafe way by the client stub.

Using apache commons-pooling to pool the instances and using each one from one thread at a time worked well though.

Answer 3

I guess I'll try to answer my own question by providing some update on futher research I did. It appears that by default older versions of Axis2 stubs may have been only "thread-compatible" (cannot make calls on the same stub instance concurrently from multiple threads - but calls to different instances is OK).

See for example:

http://markmail.org/message/3lu7x7pfo47vgnck http://markmail.org/message/sljyf6lpecxqllgx

You may experience some socket leaks, and run out of sockets if you don't call cleanup/cleanupTransport, as per this thread and many related ones:

http://issues.apache.org/jira/browse/AXIS2-3670

In some cases, at least the underlying HttpClient now seems to be thread-safe, but depending on how you generated your client, the entire stub might not be:

http://amilachinthaka.blogspot.com/2009/05/improving-axis2-client-http-transport.html