Skip to main content

PubSubHub

Thread-safe in-memory pub/sub router scoped to a Flet server process.

Subscribers are grouped by session ID and optionally by topic. Handlers can be synchronous callables or async coroutine functions:

  • global subscribers receive (message);
  • topic subscribers receive (topic, message).

This hub is used by session-scoped PubSubClient instances to fan out messages between connected sessions.

Methods

  • send_all - Sends a message to all global subscribers across all sessions.
  • send_all_on_topic - Sends a topic message to all subscribers of topic.
  • send_others - Sends a global message to all sessions except one.
  • send_others_on_topic - Sends a topic message to all subscribers except one session.
  • subscribe - Registers a global subscriber for a session.
  • subscribe_topic - Registers a topic subscriber for a session.
  • unsubscribe - Removes all global subscribers for a session.
  • unsubscribe_all - Removes both global and topic subscriptions for a session.
  • unsubscribe_topic - Removes all handlers for a specific session/topic pair.

Methods​

send_all​

send_all(message: Any)

Sends a message to all global subscribers across all sessions.

Parameters:

  • message (Any) - Payload to deliver.

send_all_on_topic​

send_all_on_topic(topic: str, message: Any)

Sends a topic message to all subscribers of topic.

Parameters:

  • topic (str) - Topic name to broadcast on.
  • message (Any) - Payload to deliver.

send_others​

send_others(except_session_id: str, message: Any)

Sends a global message to all sessions except one.

Parameters:

  • except_session_id (str) - Session ID to exclude from delivery.
  • message (Any) - Payload to deliver.

send_others_on_topic​

send_others_on_topic(except_session_id: str, topic: str, message: Any)

Sends a topic message to all subscribers except one session.

Parameters:

  • except_session_id (str) - Session ID to exclude from delivery.
  • topic (str) - Topic name to publish on.
  • message (Any) - Payload to deliver.

subscribe​

subscribe(session_id: str, handler: Callable)

Registers a global subscriber for a session.

The handler will receive one positional argument: message. Duplicate registrations of the same handler are ignored because handlers are stored in a set.

Parameters:

  • session_id (str) - Session identifier that owns this subscription.
  • handler (Callable) - Sync or async callback invoked for global messages.

subscribe_topic​

subscribe_topic(session_id: str, topic: str, handler: Union[Callable, Callable[..., Awaitable[Any]]])

Registers a topic subscriber for a session.

The handler will receive two positional arguments: (topic, message).

Parameters:

  • session_id (str) - Session identifier that owns this subscription.
  • topic (str) - Topic name to subscribe to.
  • handler (Union[Callable, Callable[..., Awaitable[Any]]]) - Sync or async callback invoked for topic messages.

unsubscribe​

unsubscribe(session_id: str)

Removes all global subscribers for a session.

This does not remove topic subscriptions; use unsubscribe_all to remove both.

Parameters:

  • session_id (str) - Session identifier to remove.

unsubscribe_all​

unsubscribe_all(session_id: str)

Removes both global and topic subscriptions for a session.

Parameters:

  • session_id (str) - Session identifier to fully unsubscribe.

unsubscribe_topic​

unsubscribe_topic(session_id: str, topic: str)

Removes all handlers for a specific session/topic pair.

Parameters:

  • session_id (str) - Session identifier to remove from the topic.
  • topic (str) - Topic to unsubscribe from.