a2a.client.base_client module

class a2a.client.base_client.BaseClient(card: AgentCard, config: ClientConfig, transport: ClientTransport, consumers: list[Callable[[tuple[Task, TaskStatusUpdateEvent | TaskArtifactUpdateEvent | None] | Message, AgentCard], Coroutine[None, Any, Any]]], middleware: list[ClientCallInterceptor])

Bases: Client

Base implementation of the A2A client, containing transport-independent logic.

async cancel_task(request: TaskIdParams, *, context: ClientCallContext | None = None, extensions: list[str] | None = None) → Task

Requests the agent to cancel a specific task.

Parameters:

  • request – The TaskIdParams object specifying the task ID.

  • context – The client call context.

  • extensions – List of extensions to be activated.

Returns:

A Task object containing the updated task status.

async close() → None

Closes the underlying transport.

async get_card(*, context: ClientCallContext | None = None, extensions: list[str] | None = None, signature_verifier: Callable[[AgentCard], None] | None = None) → AgentCard

Retrieves the agent’s card.

This will fetch the authenticated card if necessary and update the client’s internal state with the new card.

Parameters:

  • context – The client call context.

  • extensions – List of extensions to be activated.

  • signature_verifier – A callable used to verify the agent card’s signatures.

Returns:

The AgentCard for the agent.

async get_task(request: TaskQueryParams, *, context: ClientCallContext | None = None, extensions: list[str] | None = None) → Task

Retrieves the current state and history of a specific task.

Parameters:

  • request – The TaskQueryParams object specifying the task ID.

  • context – The client call context.

  • extensions – List of extensions to be activated.

Returns:

A Task object representing the current state of the task.

async get_task_callback(request: GetTaskPushNotificationConfigParams, *, context: ClientCallContext | None = None, extensions: list[str] | None = None) → TaskPushNotificationConfig

Retrieves the push notification configuration for a specific task.

Parameters:

  • request – The GetTaskPushNotificationConfigParams object specifying the task.

  • context – The client call context.

  • extensions – List of extensions to be activated.

Returns:

A TaskPushNotificationConfig object containing the configuration.

async resubscribe(request: TaskIdParams, *, context: ClientCallContext | None = None, extensions: list[str] | None = None) → AsyncIterator[tuple[Task, TaskStatusUpdateEvent | TaskArtifactUpdateEvent | None]]

Resubscribes to a task’s event stream.

This is only available if both the client and server support streaming.

Parameters:

  • request – Parameters to identify the task to resubscribe to.

  • context – The client call context.

  • extensions – List of extensions to be activated.

Yields:

An async iterator of ClientEvent objects.

Raises:

NotImplementedError – If streaming is not supported by the client or server.

async send_message(request: Message, *, configuration: MessageSendConfiguration | None = None, context: ClientCallContext | None = None, request_metadata: dict[str, Any] | None = None, extensions: list[str] | None = None) → AsyncIterator[tuple[Task, TaskStatusUpdateEvent | TaskArtifactUpdateEvent | None] | Message]

Sends a message to the agent.

This method handles both streaming and non-streaming (polling) interactions based on the client configuration and agent capabilities. It will yield events as they are received from the agent.

Parameters:

  • request – The message to send to the agent.

  • configuration – Optional per-call overrides for message sending behavior.

  • context – The client call context.

  • request_metadata – Extensions Metadata attached to the request.

  • extensions – List of extensions to be activated.

Yields:

An async iterator of ClientEvent or a final Message response.

async set_task_callback(request: TaskPushNotificationConfig, *, context: ClientCallContext | None = None, extensions: list[str] | None = None) → TaskPushNotificationConfig

Sets or updates the push notification configuration for a specific task.

Parameters:

  • request – The TaskPushNotificationConfig object with the new configuration.

  • context – The client call context.

  • extensions – List of extensions to be activated.

Returns:

The created or updated TaskPushNotificationConfig object.