:orphan:


Error Handling
==============

**Write me.**

Serialization Errors
--------------------

When you publish an event, call a procedure or return from a called
procedure, you can use any positional- and keyword-based application
payload - as long as the payload can be *serialized*.

When you try to use non-serializable payload, this will fail:

.. code:: python

    from twisted.internet.defer import inlineCallbacks

    from autobahn.wamp.types import PublishOptions
    from autobahn.wamp.exception import ApplicationError, SerializationError

    from autobahn.twisted.wamp import ApplicationSession
    from autobahn.twisted.wamp import ApplicationRunner


    class Foo:
        def __init__(self, a, b):
            self.a = a
            self.b = b


    class MyComponent(ApplicationSession):

        @inlineCallbacks
        def onJoin(self, details):
            print("session ready")

            # this object can't be serialized, so we can't use it "as is"
            # in any application payload
            foo = Foo(23, u"hello")

            # try to publish .. this will fail!
            #
            try:
                yield self.publish(u"com.example.topic1", foo, options=PublishOptions(acknowledge=True))
            except SerializationError as e:
                print("publish error: {}".format(e))

            # try to call a procedure that returns a non-serializable value .. will fail!
            #
            def get_a_foo():
                return foo

            yield self.register(get_a_foo, u"com.example.get_a_foo")

            try:
                res = yield self.call(u"com.example.get_a_foo")
            except SerializationError as e:
                print("call 1 error: {}".format(e))

            # demonstrates raising an error with valid custom payload .. will "succeed"!
            #
            def get_a_foo2():
                raise ApplicationError(u"com.example.error1", "hello", 123)

            yield self.register(get_a_foo2, u"com.example.get_a_foo2")

            try:
                res = yield self.call(u"com.example.get_a_foo2")
            except ApplicationError as e:
                print("call 2 error: {}".format(e))

            # demonstrates raising an error with non-serializable custom payload .. will "fail"!
            #
            def get_a_foo3():
                raise ApplicationError(u"com.example.error1", foo)

            yield self.register(get_a_foo3, u"com.example.get_a_foo3")

            try:
                res = yield self.call(u"com.example.get_a_foo3")
            except SerializationError as e:
                print("call 3 error: {}".format(e))

            print("Done!")


    if __name__ == '__main__':
        runner = ApplicationRunner(url=u"ws://localhost:8080/ws", realm=u"realm1",
            debug=False, debug_wamp=False)
        runner.run(MyComponent)