:orphan:

Retained Events
===============

When publishing an event, the publisher can set an option
(``retain=True``) in the ``PublishOptions`` which will cause the Broker
to retain the event being published as the most-recent event on this
topic.

Note that :doc:`Event History<Event-History>` is similar to this feature, but not the
same.

No configuration is required in Crossbar in order to take advantage of
this; it is up to the publisher.

Retrieving an Event
===================

Upon subscription, a client can pass ``get_retained=True`` in the
``SubscribeOptions``. If there is any retained event, it will be
immediately sent to the subscriber.

Example
=======

There is a completely-worked example `in the Autobahn-Python
repository <https://github.com/crossbario/autobahn-python/tree/master/examples/twisted/wamp/pubsub>`__.