'Initialisation of the WSGI app.
:param controller: object that implement methods created by routes lib
:param deserializer: object that supports webob request deserialization
through controller-like actions
:param serializer: object that supports webob response serialization
through controller-like actions'

def __init__(self, controller, deserializer, serializer=None):

    self.controller = controller
    self.deserializer = deserializer
    self.serializer = serializer
