agent-framework/python/samples/04-hosting/a2a/agent_executor.py

# Copyright (c) Microsoft. All rights reserved.

"""AgentExecutor bridge between the a2a-sdk server and Agent Framework agents.

Implements the a2a-sdk ``AgentExecutor`` interface so that incoming A2A
requests are forwarded to an Agent Framework agent and the response is
published back through the a2a-sdk event queue.
"""

from __future__ import annotations

import asyncio
import uuid
from typing import TYPE_CHECKING

from a2a.server.agent_execution.agent_executor import AgentExecutor
from a2a.types import (
    Message,
    Part,
    Role,
    TaskState,
    TaskStatus,
    TaskStatusUpdateEvent,
)

if TYPE_CHECKING:
    from a2a.server.agent_execution.context import RequestContext
    from a2a.server.events.event_queue import EventQueue
    from agent_framework import Agent


class AgentFrameworkExecutor(AgentExecutor):
    """Bridges A2A protocol requests to an Agent Framework agent.

    For each incoming ``execute`` call the executor:
    1. Extracts the user's text from the A2A ``RequestContext``.
    2. Runs the Agent Framework agent (non-streaming).
    3. Publishes the result as an A2A ``Message`` to the ``EventQueue``.
    """

    def __init__(self, agent: Agent) -> None:
        self.agent = agent

    async def execute(self, context: RequestContext, event_queue: EventQueue) -> None:
        """Run the agent and publish the response."""
        user_text = context.get_user_input()
        if not user_text:
            user_text = "Hello"

        task_id = context.task_id or str(uuid.uuid4())
        context_id = context.context_id or str(uuid.uuid4())

        # Signal that the agent is working
        await event_queue.enqueue_event(
            TaskStatusUpdateEvent(
                task_id=task_id,
                context_id=context_id,
                status=TaskStatus(state=TaskState.TASK_STATE_WORKING),
            )
        )

        try:
            response = await self.agent.run(user_text)

            # Build response text from agent messages
            response_parts: list[Part] = []
            for msg in response.messages:
                if msg.text:
                    response_parts.append(Part(text=msg.text))

            if not response_parts:
                response_parts.append(Part(text=str(response)))

            # Publish the agent's response as a completed message
            await event_queue.enqueue_event(
                TaskStatusUpdateEvent(
                    task_id=task_id,
                    context_id=context_id,
                    status=TaskStatus(
                        state=TaskState.TASK_STATE_COMPLETED,
                        message=Message(
                            message_id=str(uuid.uuid4()),
                            role=Role.ROLE_AGENT,
                            parts=response_parts,
                        ),
                    ),
                )
            )
        except asyncio.CancelledError:
            raise
        except Exception as e:
            await event_queue.enqueue_event(
                TaskStatusUpdateEvent(
                    task_id=task_id,
                    context_id=context_id,
                    status=TaskStatus(
                        state=TaskState.TASK_STATE_FAILED,
                        message=Message(
                            message_id=str(uuid.uuid4()),
                            role=Role.ROLE_AGENT,
                            parts=[Part(text=f"Agent error: {e}")],
                        ),
                    ),
                )
            )

    async def cancel(self, context: RequestContext, event_queue: EventQueue) -> None:
        """Handle cancellation by publishing a canceled status."""
        task_id = context.task_id or str(uuid.uuid4())
        context_id = context.context_id or str(uuid.uuid4())

        await event_queue.enqueue_event(
            TaskStatusUpdateEvent(
                task_id=task_id,
                context_id=context_id,
                status=TaskStatus(state=TaskState.TASK_STATE_CANCELED),
            )
        )