nat.plugins.a2a.client.client_base#

Attributes#

logger

Classes#

A2ABaseClient

Minimal A2A client for connecting to an A2A agent.

Module Contents#

logger#
class A2ABaseClient(
base_url: str,
agent_card_path: str = '/.well-known/agent-card.json',
task_timeout: datetime.timedelta = timedelta(seconds=300),
streaming: bool = True,
auth_provider: nat.authentication.interfaces.AuthProviderBase | None = None,
)#

Minimal A2A client for connecting to an A2A agent.

Args:

base_url: The base URL of the A2A agent agent_card_path: Path to agent card (default: /.well-known/agent-card.json) task_timeout: Timeout for task operations (default: 300 seconds) streaming: Enable streaming responses (default: True) auth_provider: Optional NAT authentication provider for securing requests

_base_url#
_agent_card_path = '/.well-known/agent-card.json'#
_task_timeout#
_streaming = True#
_auth_provider = None#
_httpx_client: httpx.AsyncClient | None = None#
_client: a2a.client.Client | None = None#
_agent_card: a2a.types.AgentCard | None = None#
property base_url: str#
property agent_card: a2a.types.AgentCard | None#
async _resolve_agent_card()#

Fetch the agent card from the A2A agent.

async send_message(
message_text: str,
task_id: str | None = None,
context_id: str | None = None,
) → collections.abc.AsyncGenerator[a2a.client.ClientEvent | a2a.types.Message, None]#

Send a message to the agent and stream response events.

This is the low-level A2A protocol method that yields events as they arrive. For simpler usage, prefer the high-level agent function registered by this client.

Args:

message_text: The message text to send task_id: Optional task ID to continue an existing conversation context_id: Optional context ID for the conversation

Yields:
ClientEvent | Message: The agent’s response events as they arrive.

ClientEvent is a tuple of (Task, UpdateEvent | None) Message is a direct message response

async get_task(
task_id: str,
history_length: int | None = None,
) → a2a.types.Task#

Get the status and details of a specific task.

This is an A2A protocol operation for retrieving task information.

Args:

task_id: The unique identifier of the task history_length: Optional limit on the number of history messages to retrieve

Returns:

Task: The task object with current status and history

async cancel_task(task_id: str) → a2a.types.Task#

Cancel a running task.

This is an A2A protocol operation for canceling tasks.

Args:

task_id: The unique identifier of the task to cancel

Returns:

Task: The task object with updated status

async send_message_streaming(
message_text: str,
task_id: str | None = None,
context_id: str | None = None,
) → collections.abc.AsyncGenerator[a2a.client.ClientEvent | a2a.types.Message, None]#

Send a message to the agent and stream response events (alias for send_message).

This method provides an explicit streaming interface that mirrors the A2A SDK pattern. It is functionally identical to send_message(), which already streams events.

Args:

message_text: The message text to send task_id: Optional task ID to continue an existing conversation context_id: Optional context ID for the conversation

Yields:

ClientEvent | Message: The agent’s response events as they arrive.

extract_text_from_parts(parts: list) → list[str]#

Extract text content from A2A message parts.

Args:

parts: List of A2A Part objects

Returns:

List of text strings extracted from the parts

extract_text_from_task(task) → str#

Extract text response from an A2A Task object.

This method understands the A2A protocol structure and extracts the final text response from a completed task, prioritizing artifacts over history.

Args:

task: A2A Task object

Returns:

Extracted text response or status message

Priority order:

  1. Check task status (return error/progress if not completed)

  2. Extract from task.artifacts (structured output)

  3. Fallback to last agent message in task.history

extract_text_from_events(events: list) → str#

Extract text response from a list of A2A events.

This is a convenience method that handles both Message and ClientEvent types.

Args:

events: List of A2A events (ClientEvent or Message objects)

Returns:

Extracted text response