feat: add MCP support (#20716)

Co-authored-by: QuantumGhost <obelisk.reg+git@gmail.com>
This commit is contained in:
Novice
2025-07-10 14:01:34 +08:00
committed by GitHub
parent 18b58424ec
commit 535fff62f3
54 changed files with 6634 additions and 154 deletions

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import logging
import queue
from collections.abc import Callable
from concurrent.futures import ThreadPoolExecutor
from contextlib import ExitStack
from datetime import timedelta
from types import TracebackType
from typing import Any, Generic, Self, TypeVar
from httpx import HTTPStatusError
from pydantic import BaseModel
from core.mcp.error import MCPAuthError, MCPConnectionError
from core.mcp.types import (
CancelledNotification,
ClientNotification,
ClientRequest,
ClientResult,
ErrorData,
JSONRPCError,
JSONRPCMessage,
JSONRPCNotification,
JSONRPCRequest,
JSONRPCResponse,
MessageMetadata,
RequestId,
RequestParams,
ServerMessageMetadata,
ServerNotification,
ServerRequest,
ServerResult,
SessionMessage,
)
SendRequestT = TypeVar("SendRequestT", ClientRequest, ServerRequest)
SendResultT = TypeVar("SendResultT", ClientResult, ServerResult)
SendNotificationT = TypeVar("SendNotificationT", ClientNotification, ServerNotification)
ReceiveRequestT = TypeVar("ReceiveRequestT", ClientRequest, ServerRequest)
ReceiveResultT = TypeVar("ReceiveResultT", bound=BaseModel)
ReceiveNotificationT = TypeVar("ReceiveNotificationT", ClientNotification, ServerNotification)
DEFAULT_RESPONSE_READ_TIMEOUT = 1.0
class RequestResponder(Generic[ReceiveRequestT, SendResultT]):
"""Handles responding to MCP requests and manages request lifecycle.
This class MUST be used as a context manager to ensure proper cleanup and
cancellation handling:
Example:
with request_responder as resp:
resp.respond(result)
The context manager ensures:
1. Proper cancellation scope setup and cleanup
2. Request completion tracking
3. Cleanup of in-flight requests
"""
request: ReceiveRequestT
_session: Any
_on_complete: Callable[["RequestResponder[ReceiveRequestT, SendResultT]"], Any]
def __init__(
self,
request_id: RequestId,
request_meta: RequestParams.Meta | None,
request: ReceiveRequestT,
session: """BaseSession[
SendRequestT,
SendNotificationT,
SendResultT,
ReceiveRequestT,
ReceiveNotificationT
]""",
on_complete: Callable[["RequestResponder[ReceiveRequestT, SendResultT]"], Any],
) -> None:
self.request_id = request_id
self.request_meta = request_meta
self.request = request
self._session = session
self._completed = False
self._on_complete = on_complete
self._entered = False # Track if we're in a context manager
def __enter__(self) -> "RequestResponder[ReceiveRequestT, SendResultT]":
"""Enter the context manager, enabling request cancellation tracking."""
self._entered = True
return self
def __exit__(
self,
exc_type: type[BaseException] | None,
exc_val: BaseException | None,
exc_tb: TracebackType | None,
) -> None:
"""Exit the context manager, performing cleanup and notifying completion."""
try:
if self._completed:
self._on_complete(self)
finally:
self._entered = False
def respond(self, response: SendResultT | ErrorData) -> None:
"""Send a response for this request.
Must be called within a context manager block.
Raises:
RuntimeError: If not used within a context manager
AssertionError: If request was already responded to
"""
if not self._entered:
raise RuntimeError("RequestResponder must be used as a context manager")
assert not self._completed, "Request already responded to"
self._completed = True
self._session._send_response(request_id=self.request_id, response=response)
def cancel(self) -> None:
"""Cancel this request and mark it as completed."""
if not self._entered:
raise RuntimeError("RequestResponder must be used as a context manager")
self._completed = True # Mark as completed so it's removed from in_flight
# Send an error response to indicate cancellation
self._session._send_response(
request_id=self.request_id,
response=ErrorData(code=0, message="Request cancelled", data=None),
)
class BaseSession(
Generic[
SendRequestT,
SendNotificationT,
SendResultT,
ReceiveRequestT,
ReceiveNotificationT,
],
):
"""
Implements an MCP "session" on top of read/write streams, including features
like request/response linking, notifications, and progress.
This class is a context manager that automatically starts processing
messages when entered.
"""
_response_streams: dict[RequestId, queue.Queue[JSONRPCResponse | JSONRPCError]]
_request_id: int
_in_flight: dict[RequestId, RequestResponder[ReceiveRequestT, SendResultT]]
_receive_request_type: type[ReceiveRequestT]
_receive_notification_type: type[ReceiveNotificationT]
def __init__(
self,
read_stream: queue.Queue,
write_stream: queue.Queue,
receive_request_type: type[ReceiveRequestT],
receive_notification_type: type[ReceiveNotificationT],
# If none, reading will never time out
read_timeout_seconds: timedelta | None = None,
) -> None:
self._read_stream = read_stream
self._write_stream = write_stream
self._response_streams = {}
self._request_id = 0
self._receive_request_type = receive_request_type
self._receive_notification_type = receive_notification_type
self._session_read_timeout_seconds = read_timeout_seconds
self._in_flight = {}
self._exit_stack = ExitStack()
def __enter__(self) -> Self:
self._executor = ThreadPoolExecutor()
self._receiver_future = self._executor.submit(self._receive_loop)
return self
def check_receiver_status(self) -> None:
if self._receiver_future.done():
self._receiver_future.result()
def __exit__(
self, exc_type: type[BaseException] | None, exc_val: BaseException | None, exc_tb: TracebackType | None
) -> None:
self._exit_stack.close()
self._read_stream.put(None)
self._write_stream.put(None)
def send_request(
self,
request: SendRequestT,
result_type: type[ReceiveResultT],
request_read_timeout_seconds: timedelta | None = None,
metadata: MessageMetadata = None,
) -> ReceiveResultT:
"""
Sends a request and wait for a response. Raises an McpError if the
response contains an error. If a request read timeout is provided, it
will take precedence over the session read timeout.
Do not use this method to emit notifications! Use send_notification()
instead.
"""
self.check_receiver_status()
request_id = self._request_id
self._request_id = request_id + 1
response_queue: queue.Queue[JSONRPCResponse | JSONRPCError] = queue.Queue()
self._response_streams[request_id] = response_queue
try:
jsonrpc_request = JSONRPCRequest(
jsonrpc="2.0",
id=request_id,
**request.model_dump(by_alias=True, mode="json", exclude_none=True),
)
self._write_stream.put(SessionMessage(message=JSONRPCMessage(jsonrpc_request), metadata=metadata))
timeout = DEFAULT_RESPONSE_READ_TIMEOUT
if request_read_timeout_seconds is not None:
timeout = float(request_read_timeout_seconds.total_seconds())
elif self._session_read_timeout_seconds is not None:
timeout = float(self._session_read_timeout_seconds.total_seconds())
while True:
try:
response_or_error = response_queue.get(timeout=timeout)
break
except queue.Empty:
self.check_receiver_status()
continue
if response_or_error is None:
raise MCPConnectionError(
ErrorData(
code=500,
message="No response received",
)
)
elif isinstance(response_or_error, JSONRPCError):
if response_or_error.error.code == 401:
raise MCPAuthError(
ErrorData(code=response_or_error.error.code, message=response_or_error.error.message)
)
else:
raise MCPConnectionError(
ErrorData(code=response_or_error.error.code, message=response_or_error.error.message)
)
else:
return result_type.model_validate(response_or_error.result)
finally:
self._response_streams.pop(request_id, None)
def send_notification(
self,
notification: SendNotificationT,
related_request_id: RequestId | None = None,
) -> None:
"""
Emits a notification, which is a one-way message that does not expect
a response.
"""
self.check_receiver_status()
# Some transport implementations may need to set the related_request_id
# to attribute to the notifications to the request that triggered them.
jsonrpc_notification = JSONRPCNotification(
jsonrpc="2.0",
**notification.model_dump(by_alias=True, mode="json", exclude_none=True),
)
session_message = SessionMessage(
message=JSONRPCMessage(jsonrpc_notification),
metadata=ServerMessageMetadata(related_request_id=related_request_id) if related_request_id else None,
)
self._write_stream.put(session_message)
def _send_response(self, request_id: RequestId, response: SendResultT | ErrorData) -> None:
if isinstance(response, ErrorData):
jsonrpc_error = JSONRPCError(jsonrpc="2.0", id=request_id, error=response)
session_message = SessionMessage(message=JSONRPCMessage(jsonrpc_error))
self._write_stream.put(session_message)
else:
jsonrpc_response = JSONRPCResponse(
jsonrpc="2.0",
id=request_id,
result=response.model_dump(by_alias=True, mode="json", exclude_none=True),
)
session_message = SessionMessage(message=JSONRPCMessage(jsonrpc_response))
self._write_stream.put(session_message)
def _receive_loop(self) -> None:
"""
Main message processing loop.
In a real synchronous implementation, this would likely run in a separate thread.
"""
while True:
try:
# Attempt to receive a message (this would be blocking in a synchronous context)
message = self._read_stream.get(timeout=DEFAULT_RESPONSE_READ_TIMEOUT)
if message is None:
break
if isinstance(message, HTTPStatusError):
response_queue = self._response_streams.get(self._request_id - 1)
if response_queue is not None:
response_queue.put(
JSONRPCError(
jsonrpc="2.0",
id=self._request_id - 1,
error=ErrorData(code=message.response.status_code, message=message.args[0]),
)
)
else:
self._handle_incoming(RuntimeError(f"Received response with an unknown request ID: {message}"))
elif isinstance(message, Exception):
self._handle_incoming(message)
elif isinstance(message.message.root, JSONRPCRequest):
validated_request = self._receive_request_type.model_validate(
message.message.root.model_dump(by_alias=True, mode="json", exclude_none=True)
)
responder = RequestResponder(
request_id=message.message.root.id,
request_meta=validated_request.root.params.meta if validated_request.root.params else None,
request=validated_request,
session=self,
on_complete=lambda r: self._in_flight.pop(r.request_id, None),
)
self._in_flight[responder.request_id] = responder
self._received_request(responder)
if not responder._completed:
self._handle_incoming(responder)
elif isinstance(message.message.root, JSONRPCNotification):
try:
notification = self._receive_notification_type.model_validate(
message.message.root.model_dump(by_alias=True, mode="json", exclude_none=True)
)
# Handle cancellation notifications
if isinstance(notification.root, CancelledNotification):
cancelled_id = notification.root.params.requestId
if cancelled_id in self._in_flight:
self._in_flight[cancelled_id].cancel()
else:
self._received_notification(notification)
self._handle_incoming(notification)
except Exception as e:
# For other validation errors, log and continue
logging.warning(f"Failed to validate notification: {e}. Message was: {message.message.root}")
else: # Response or error
response_queue = self._response_streams.get(message.message.root.id)
if response_queue is not None:
response_queue.put(message.message.root)
else:
self._handle_incoming(RuntimeError(f"Server Error: {message}"))
except queue.Empty:
continue
except Exception as e:
logging.exception("Error in message processing loop")
raise
def _received_request(self, responder: RequestResponder[ReceiveRequestT, SendResultT]) -> None:
"""
Can be overridden by subclasses to handle a request without needing to
listen on the message stream.
If the request is responded to within this method, it will not be
forwarded on to the message stream.
"""
pass
def _received_notification(self, notification: ReceiveNotificationT) -> None:
"""
Can be overridden by subclasses to handle a notification without needing
to listen on the message stream.
"""
pass
def send_progress_notification(
self, progress_token: str | int, progress: float, total: float | None = None
) -> None:
"""
Sends a progress notification for a request that is currently being
processed.
"""
pass
def _handle_incoming(
self,
req: RequestResponder[ReceiveRequestT, SendResultT] | ReceiveNotificationT | Exception,
) -> None:
"""A generic handler for incoming messages. Overwritten by subclasses."""
pass

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from datetime import timedelta
from typing import Any, Protocol
from pydantic import AnyUrl, TypeAdapter
from configs import dify_config
from core.mcp import types
from core.mcp.entities import SUPPORTED_PROTOCOL_VERSIONS, RequestContext
from core.mcp.session.base_session import BaseSession, RequestResponder
DEFAULT_CLIENT_INFO = types.Implementation(name="Dify", version=dify_config.project.version)
class SamplingFnT(Protocol):
def __call__(
self,
context: RequestContext["ClientSession", Any],
params: types.CreateMessageRequestParams,
) -> types.CreateMessageResult | types.ErrorData: ...
class ListRootsFnT(Protocol):
def __call__(self, context: RequestContext["ClientSession", Any]) -> types.ListRootsResult | types.ErrorData: ...
class LoggingFnT(Protocol):
def __call__(
self,
params: types.LoggingMessageNotificationParams,
) -> None: ...
class MessageHandlerFnT(Protocol):
def __call__(
self,
message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
) -> None: ...
def _default_message_handler(
message: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
) -> None:
if isinstance(message, Exception):
raise ValueError(str(message))
elif isinstance(message, (types.ServerNotification | RequestResponder)):
pass
def _default_sampling_callback(
context: RequestContext["ClientSession", Any],
params: types.CreateMessageRequestParams,
) -> types.CreateMessageResult | types.ErrorData:
return types.ErrorData(
code=types.INVALID_REQUEST,
message="Sampling not supported",
)
def _default_list_roots_callback(
context: RequestContext["ClientSession", Any],
) -> types.ListRootsResult | types.ErrorData:
return types.ErrorData(
code=types.INVALID_REQUEST,
message="List roots not supported",
)
def _default_logging_callback(
params: types.LoggingMessageNotificationParams,
) -> None:
pass
ClientResponse: TypeAdapter[types.ClientResult | types.ErrorData] = TypeAdapter(types.ClientResult | types.ErrorData)
class ClientSession(
BaseSession[
types.ClientRequest,
types.ClientNotification,
types.ClientResult,
types.ServerRequest,
types.ServerNotification,
]
):
def __init__(
self,
read_stream,
write_stream,
read_timeout_seconds: timedelta | None = None,
sampling_callback: SamplingFnT | None = None,
list_roots_callback: ListRootsFnT | None = None,
logging_callback: LoggingFnT | None = None,
message_handler: MessageHandlerFnT | None = None,
client_info: types.Implementation | None = None,
) -> None:
super().__init__(
read_stream,
write_stream,
types.ServerRequest,
types.ServerNotification,
read_timeout_seconds=read_timeout_seconds,
)
self._client_info = client_info or DEFAULT_CLIENT_INFO
self._sampling_callback = sampling_callback or _default_sampling_callback
self._list_roots_callback = list_roots_callback or _default_list_roots_callback
self._logging_callback = logging_callback or _default_logging_callback
self._message_handler = message_handler or _default_message_handler
def initialize(self) -> types.InitializeResult:
sampling = types.SamplingCapability()
roots = types.RootsCapability(
# TODO: Should this be based on whether we
# _will_ send notifications, or only whether
# they're supported?
listChanged=True,
)
result = self.send_request(
types.ClientRequest(
types.InitializeRequest(
method="initialize",
params=types.InitializeRequestParams(
protocolVersion=types.LATEST_PROTOCOL_VERSION,
capabilities=types.ClientCapabilities(
sampling=sampling,
experimental=None,
roots=roots,
),
clientInfo=self._client_info,
),
)
),
types.InitializeResult,
)
if result.protocolVersion not in SUPPORTED_PROTOCOL_VERSIONS:
raise RuntimeError(f"Unsupported protocol version from the server: {result.protocolVersion}")
self.send_notification(
types.ClientNotification(types.InitializedNotification(method="notifications/initialized"))
)
return result
def send_ping(self) -> types.EmptyResult:
"""Send a ping request."""
return self.send_request(
types.ClientRequest(
types.PingRequest(
method="ping",
)
),
types.EmptyResult,
)
def send_progress_notification(
self, progress_token: str | int, progress: float, total: float | None = None
) -> None:
"""Send a progress notification."""
self.send_notification(
types.ClientNotification(
types.ProgressNotification(
method="notifications/progress",
params=types.ProgressNotificationParams(
progressToken=progress_token,
progress=progress,
total=total,
),
),
)
)
def set_logging_level(self, level: types.LoggingLevel) -> types.EmptyResult:
"""Send a logging/setLevel request."""
return self.send_request(
types.ClientRequest(
types.SetLevelRequest(
method="logging/setLevel",
params=types.SetLevelRequestParams(level=level),
)
),
types.EmptyResult,
)
def list_resources(self) -> types.ListResourcesResult:
"""Send a resources/list request."""
return self.send_request(
types.ClientRequest(
types.ListResourcesRequest(
method="resources/list",
)
),
types.ListResourcesResult,
)
def list_resource_templates(self) -> types.ListResourceTemplatesResult:
"""Send a resources/templates/list request."""
return self.send_request(
types.ClientRequest(
types.ListResourceTemplatesRequest(
method="resources/templates/list",
)
),
types.ListResourceTemplatesResult,
)
def read_resource(self, uri: AnyUrl) -> types.ReadResourceResult:
"""Send a resources/read request."""
return self.send_request(
types.ClientRequest(
types.ReadResourceRequest(
method="resources/read",
params=types.ReadResourceRequestParams(uri=uri),
)
),
types.ReadResourceResult,
)
def subscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
"""Send a resources/subscribe request."""
return self.send_request(
types.ClientRequest(
types.SubscribeRequest(
method="resources/subscribe",
params=types.SubscribeRequestParams(uri=uri),
)
),
types.EmptyResult,
)
def unsubscribe_resource(self, uri: AnyUrl) -> types.EmptyResult:
"""Send a resources/unsubscribe request."""
return self.send_request(
types.ClientRequest(
types.UnsubscribeRequest(
method="resources/unsubscribe",
params=types.UnsubscribeRequestParams(uri=uri),
)
),
types.EmptyResult,
)
def call_tool(
self,
name: str,
arguments: dict[str, Any] | None = None,
read_timeout_seconds: timedelta | None = None,
) -> types.CallToolResult:
"""Send a tools/call request."""
return self.send_request(
types.ClientRequest(
types.CallToolRequest(
method="tools/call",
params=types.CallToolRequestParams(name=name, arguments=arguments),
)
),
types.CallToolResult,
request_read_timeout_seconds=read_timeout_seconds,
)
def list_prompts(self) -> types.ListPromptsResult:
"""Send a prompts/list request."""
return self.send_request(
types.ClientRequest(
types.ListPromptsRequest(
method="prompts/list",
)
),
types.ListPromptsResult,
)
def get_prompt(self, name: str, arguments: dict[str, str] | None = None) -> types.GetPromptResult:
"""Send a prompts/get request."""
return self.send_request(
types.ClientRequest(
types.GetPromptRequest(
method="prompts/get",
params=types.GetPromptRequestParams(name=name, arguments=arguments),
)
),
types.GetPromptResult,
)
def complete(
self,
ref: types.ResourceReference | types.PromptReference,
argument: dict[str, str],
) -> types.CompleteResult:
"""Send a completion/complete request."""
return self.send_request(
types.ClientRequest(
types.CompleteRequest(
method="completion/complete",
params=types.CompleteRequestParams(
ref=ref,
argument=types.CompletionArgument(**argument),
),
)
),
types.CompleteResult,
)
def list_tools(self) -> types.ListToolsResult:
"""Send a tools/list request."""
return self.send_request(
types.ClientRequest(
types.ListToolsRequest(
method="tools/list",
)
),
types.ListToolsResult,
)
def send_roots_list_changed(self) -> None:
"""Send a roots/list_changed notification."""
self.send_notification(
types.ClientNotification(
types.RootsListChangedNotification(
method="notifications/roots/list_changed",
)
)
)
def _received_request(self, responder: RequestResponder[types.ServerRequest, types.ClientResult]) -> None:
ctx = RequestContext[ClientSession, Any](
request_id=responder.request_id,
meta=responder.request_meta,
session=self,
lifespan_context=None,
)
match responder.request.root:
case types.CreateMessageRequest(params=params):
with responder:
response = self._sampling_callback(ctx, params)
client_response = ClientResponse.validate_python(response)
responder.respond(client_response)
case types.ListRootsRequest():
with responder:
list_roots_response = self._list_roots_callback(ctx)
client_response = ClientResponse.validate_python(list_roots_response)
responder.respond(client_response)
case types.PingRequest():
with responder:
return responder.respond(types.ClientResult(root=types.EmptyResult()))
def _handle_incoming(
self,
req: RequestResponder[types.ServerRequest, types.ClientResult] | types.ServerNotification | Exception,
) -> None:
"""Handle incoming messages by forwarding to the message handler."""
self._message_handler(req)
def _received_notification(self, notification: types.ServerNotification) -> None:
"""Handle notifications from the server."""
# Process specific notification types
match notification.root:
case types.LoggingMessageNotification(params=params):
self._logging_callback(params)
case _:
pass