The MessageHandler Class

Every wampy Client requires a MessageHandler. This is a class with a list of Messages it will accept and a “handle” method for each.

The default MessageHandler contains everything you need to use WAMP in your microservices, but you may want to add more behaviour such as logging messages, encrypting messages, appending meta data or custom authorisation.

If you want to define your own MessageHandler then you must subclass the default and override the “handle” methods for each Message customisation you need.

Note that whenever the Session receives a Message it calls handle_message on the MessageHandler. You can override this if you want to add global behaviour changes. handle_message will delegate to specific handlers, e.g. handle_invocation.

For example.

from wampy.message_handler import MessageHandler


class CustomHandler(MessageHandler):

    def handle_welcome(self, message_obj):
        # maybe do some auth stuff here
        super(CustomHandler, self).handle_welcome(message_obj)
        # and maybe then some other stuff now like alerting

There may be no need to even do what wampy does if your application already has patterns for handling WAMP messages! In which case override but don’t call super - just do your own thing.

Then your Client should be initialised with an instance of the custom handler.

from wampy.peers.clients import Client

client = Client(message_handler=CustomHandler())