dxlclient.callbacks module

Classes for the different DXL message callbacks.

class dxlclient.callbacks.EventCallback

Bases: dxlclient.callbacks.MessageCallback

Concrete instances of this interface are used to receive dxlclient.message.Event messages.

To receive events, a concrete instance of this callback must be created and registered with a dxlclient.client.DxlClient instance via the dxlclient.client.DxlClient.add_event_callback() method.

The following is a simple example of using an event callback:

from dxlclient.callbacks import EventCallback

class MyEventCallback(EventCallback):
    def on_event(self, event):
        print("Received event! " + event.source_client_id)

dxl_client.add_event_callback("/testeventtopic", MyEventCallback())

NOTE: By default when registering an event callback the client will automatically subscribe (dxlclient.client.DxlClient.subscribe()) to the topic.

The following demonstrates a client that is sending an event message that would be received by the callback above.

from dxlclient.message import Event

# Create the event message
evt = Event("/testeventtopic")

# Populate the event payload
evt.payload = "testing".encode()

# Send the event
dxl_client.send_event(evt)

Constructor

on_event(event)

Invoked when an dxlclient.message.Event has been received.

Parameters:event -- The dxlclient.message.Event message that was received

class dxlclient.callbacks.MessageCallback

Bases: dxlclient._BaseObject

Base class for the different callbacks

Constructor

class dxlclient.callbacks.RequestCallback

Bases: dxlclient.callbacks.MessageCallback

Concrete instances of this interface are used to receive dxlclient.message.Request messages.

Request callbacks are typically used when implementing a "service".

See dxlclient.service.ServiceRegistrationInfo for more information on how to register a service.

Constructor

on_request(request)

Invoked when an dxlclient.message.Request has been received.

Parameters:request -- The dxlclient.message.Request message that was received

class dxlclient.callbacks.ResponseCallback

Bases: dxlclient.callbacks.MessageCallback

Concrete instances of this interface are used to receive dxlclient.message.Response messages.

Response callbacks are typically used when invoking a service asynchronously.

The following is a simple example of using a response callback with an asynchronous service invocation:

from dxlclient.message import Request
from dxlclient.callbacks import ResponseCallback

class MyResponseCallback(ResponseCallback):
    def on_response(self, response):
        print("Received response! " + response.service_id)

request = Request("/testservice/testrequesttopic")
dxl_client.async_request(request, MyResponseCallback())

Constructor

on_response(response)

Invoked when an dxlclient.message.Response has been received.

Parameters:response -- The dxlclient.message.Response message that was received