Data storage and publishing

In order to publish data to listeners, Tornadose utilizes a data store concept somewhat reminiscent of that used in Flux. In short, subscribers start listening to a data store and are notified when there are updates.

class tornadose.stores.BaseStore(*args, **kwargs)

Base class for all data store types.

At a minimum, derived classes should implement submit and publish methods.

deregister(subscriber)

Stop publishing to a subscriber.

initialize(*args, **kwargs)

Hook for doing custom initialization. Child classes should implement this method instead of overwriting __init__.

publish()

Push messages to all listeners. This method must be implemented by child classes. A recommended way to implement this method is as a looping coroutine which yields until new data is available via the submit() method.

register(subscriber)

Register a new subscriber. This method should be invoked by listeners to start receiving messages.

submit(message)

Add a new message to be pushed to subscribers. This method must be implemented by child classes.

This method exists to store new data. To actually publish the data, implement the publish method.

class tornadose.stores.DataStore(*args, **kwargs)

Generic object for producing data to feed to clients.

To use this, simply instantiate and update the data property whenever new data is available. When creating a new EventSource handler, specify the DataStore instance so that the EventSource can listen for updates.

class tornadose.stores.QueueStore(*args, **kwargs)

Publish data via queues.

This class is meant to be used in cases where subscribers should not miss any data. Compared to the DataStore class, new messages to be broadcast to clients are put in a queue to be processed in order.

QueueStore will work with any tornado.web.RequestHandler subclasses which implement a submit method. It is recommended that a custom subscription handler’s submit() method also utilize a queue to avoid losing data. The subscriber must also register/deregister itself with the QueueStore via the QueueStore.register() and QueueStore.deregister() methods.

A QueueStore-compatible request handler is included in tornadose.handlers.WebSocketSubscriber.