pandemia.messagebus

Simple synchronous messagebus implementation.

Module Contents

Classes

MessageBus

Message broker.

Attributes

log

pandemia.messagebus.log
class pandemia.messagebus.MessageBus

Message broker.

Objects subscribe to this bus by providing a callback function that is invoked whenever a message is published. Multiple callbacks may be registered for a single topic, in which case they are invoked in-order.

Callbacks may return a value, MessageBus.CONSUME, which stops propagation of the event.

Topics do not need creating explicitly.

CONSUME = True
pub
sub
subscribe(topic: str, callback: Callable, owner: Any) → None

Subscribe to a topic, providing a callback function that will be invoked when an event is published on that topic.

Parameters:

  • topic (str) – The topic to respond to

  • callback (callable) – The function to invoke when an event is called

  • owner (object) – The object ‘owning’ this subscription. Used to unsubscribe.

publish(topic: str, *args, **kwargs) → None

Publish an event to the messagebus on the topic given.

All handlers will be called in the order they subscribed.

Parameters:

  • topic (str) – The topic to publish on

  • *args – Positional arguments to the callback

  • **kwargs – Keyword arguments to the callback