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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: 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 (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.