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Wrap JSONRPC messages with SessionMessage for metadata support (#590)

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ihrpr 2025-05-02 14:29:00 +01:00 • committed by GitHub
commit da0cf22355
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1 changed files with 286 additions and 173 deletions
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20
src/mcp/client/websocket.py
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@ -10,6 +10,7 @@ from websockets.asyncio.client import connect as ws_connect
from websockets.typing import Subprotocol
import mcp.types as types
from mcp.shared.message import SessionMessage
logger = logging.getLogger(__name__)
@ -19,8 +20,8 @@ async def websocket_client(
url: str,
) -> AsyncGenerator[
tuple[
MemoryObjectReceiveStream[types.JSONRPCMessage | Exception],
MemoryObjectSendStream[types.JSONRPCMessage],
MemoryObjectReceiveStream[SessionMessage | Exception],
MemoryObjectSendStream[SessionMessage],
],
None,
]:
@ -39,10 +40,10 @@ async def websocket_client(
# Create two in-memory streams:
# - One for incoming messages (read_stream, written by ws_reader)
# - One for outgoing messages (write_stream, read by ws_writer)
read_stream: MemoryObjectReceiveStream[types.JSONRPCMessage | Exception]
read_stream_writer: MemoryObjectSendStream[types.JSONRPCMessage | Exception]
write_stream: MemoryObjectSendStream[types.JSONRPCMessage]
write_stream_reader: MemoryObjectReceiveStream[types.JSONRPCMessage]
read_stream: MemoryObjectReceiveStream[SessionMessage | Exception]
read_stream_writer: MemoryObjectSendStream[SessionMessage | Exception]
write_stream: MemoryObjectSendStream[SessionMessage]
write_stream_reader: MemoryObjectReceiveStream[SessionMessage]
read_stream_writer, read_stream = anyio.create_memory_object_stream(0)
write_stream, write_stream_reader = anyio.create_memory_object_stream(0)
@ -59,7 +60,8 @@ async def websocket_client(
async for raw_text in ws:
try:
message = types.JSONRPCMessage.model_validate_json(raw_text)
await read_stream_writer.send(message)
session_message = SessionMessage(message)
await read_stream_writer.send(session_message)
except ValidationError as exc:
# If JSON parse or model validation fails, send the exception
await read_stream_writer.send(exc)
@ -70,9 +72,9 @@ async def websocket_client(
sends them to the server.
"""
async with write_stream_reader:
async for message in write_stream_reader:
async for session_message in write_stream_reader:
# Convert to a dict, then to JSON
msg_dict = message.model_dump(
msg_dict = session_message.message.model_dump(
by_alias=True, mode="json", exclude_none=True
)
await ws.send(json.dumps(msg_dict))