fix: drift in BaseAgentExecutor and uses it in examples

examples/google_adk/calendar_agent/adk_agent_executor.py

@@ -10,8 +10,7 @@
 from google.adk.events import Event
 from google.genai import types
 
-from a2a.server.agent_execution import AgentExecutor
-from a2a.server.agent_execution.context import RequestContext
+from a2a.server.agent_execution import BaseAgentExecutor, RequestContext
 from a2a.server.events.event_queue import EventQueue
 from a2a.server.tasks import TaskUpdater
 from a2a.types import (
@@ -22,9 +21,7 @@
     Part,
     TaskState,
     TextPart,
-    UnsupportedOperationError,
 )
-from a2a.utils.errors import ServerError
 from a2a.utils.message import new_agent_text_message
 
 
@@ -40,7 +37,7 @@
 auth_receive_timeout_seconds = 60
 
 
-class ADKAgentExecutor(AgentExecutor):
+class ADKAgentExecutor(BaseAgentExecutor):
     """An AgentExecutor that runs an ADK-based Agent."""
 
     _awaiting_auth: dict[str, asyncio.Future]
@@ -221,10 +218,6 @@ async def execute(
         )
         logger.debug('[Calendar] execute exiting')
 
-    async def cancel(self, context: RequestContext, event_queue: EventQueue):
-        # Ideally: kill any ongoing tasks.
-        raise ServerError(error=UnsupportedOperationError())
-
     async def on_auth_callback(self, state: str, uri: str):
         self._awaiting_auth[state].set_result(uri)
 

examples/helloworld/agent_executor.py

@@ -1,6 +1,6 @@
 from typing_extensions import override
 
-from a2a.server.agent_execution import AgentExecutor, RequestContext
+from a2a.server.agent_execution import BaseAgentExecutor, RequestContext
 from a2a.server.events import EventQueue
 from a2a.utils import new_agent_text_message
 
@@ -12,7 +12,7 @@ async def invoke(self) -> str:
         return 'Hello World'
 
 
-class HelloWorldAgentExecutor(AgentExecutor):
+class HelloWorldAgentExecutor(BaseAgentExecutor):
     """Test AgentProxy Implementation."""
 
     def __init__(self):
@@ -26,9 +26,3 @@ async def execute(
     ) -> None:
         result = await self.agent.invoke()
         event_queue.enqueue_event(new_agent_text_message(result))
-
-    @override
-    async def cancel(
-        self, context: RequestContext, event_queue: EventQueue
-    ) -> None:
-        raise Exception('cancel not supported')

examples/langgraph/agent_executor.py

@@ -1,7 +1,7 @@
 from agent import CurrencyAgent
 from typing_extensions import override
 
-from a2a.server.agent_execution import AgentExecutor, RequestContext
+from a2a.server.agent_execution import BaseAgentExecutor, RequestContext
 from a2a.server.events.event_queue import EventQueue
 from a2a.types import (
     TaskArtifactUpdateEvent,
@@ -12,7 +12,7 @@
 from a2a.utils import new_agent_text_message, new_task, new_text_artifact
 
 
-class CurrencyAgentExecutor(AgentExecutor):
+class CurrencyAgentExecutor(BaseAgentExecutor):
     """Currency AgentExecutor Example."""
 
     def __init__(self):
@@ -89,9 +89,3 @@ async def execute(
                         taskId=task.id,
                     )
                 )
-
-    @override
-    async def cancel(
-        self, context: RequestContext, event_queue: EventQueue
-    ) -> None:
-        raise Exception('cancel not supported')

src/a2a/server/agent_execution/__init__.py

@@ -1,5 +1,6 @@
 from a2a.server.agent_execution.agent_executor import AgentExecutor
+from a2a.server.agent_execution.base_agent_executor import BaseAgentExecutor
 from a2a.server.agent_execution.context import RequestContext
 
 
-__all__ = ['AgentExecutor', 'RequestContext']
+__all__ = ['AgentExecutor', 'BaseAgentExecutor', 'RequestContext']

src/a2a/server/agent_execution/base_agent_executor.py

@@ -1,48 +1,14 @@
 from a2a.server.agent_execution.agent_executor import AgentExecutor
+from a2a.server.agent_execution.context import RequestContext
 from a2a.server.events.event_queue import EventQueue
-from a2a.types import (
-    A2AError,
-    CancelTaskRequest,
-    SendMessageRequest,
-    SendStreamingMessageRequest,
-    Task,
-    TaskResubscriptionRequest,
-    UnsupportedOperationError,
-)
+from a2a.types import A2AError, UnsupportedOperationError
 
 
 class BaseAgentExecutor(AgentExecutor):
     """Base AgentExecutor which returns unsupported operation error."""
 
-    async def on_message_send(
-        self,
-        request: SendMessageRequest,
-        event_queue: EventQueue,
-        task: Task | None,
-    ) -> None:
-        """Handler for 'message/send' requests."""
+    async def execute(self, context: RequestContext, event_queue: EventQueue):
         event_queue.enqueue_event(A2AError(UnsupportedOperationError()))
 
-    async def on_message_stream(
-        self,
-        request: SendStreamingMessageRequest,
-        event_queue: EventQueue,
-        task: Task | None,
-    ) -> None:
-        """Handler for 'message/stream' requests."""
-        event_queue.enqueue_event(A2AError(UnsupportedOperationError()))
-
-    async def on_cancel(
-        self, request: CancelTaskRequest, event_queue: EventQueue, task: Task
-    ) -> None:
-        """Handler for 'tasks/cancel' requests."""
-        event_queue.enqueue_event(A2AError(UnsupportedOperationError()))
-
-    async def on_resubscribe(
-        self,
-        request: TaskResubscriptionRequest,
-        event_queue: EventQueue,
-        task: Task,
-    ) -> None:
-        """Handler for 'tasks/resubscribe' requests."""
+    async def cancel(self, context: RequestContext, event_queue: EventQueue):
         event_queue.enqueue_event(A2AError(UnsupportedOperationError()))