ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

chapter9/gaia-experience/AWorld/aworld/mcp_client/server.py

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+from __future__ import annotations
+
+import abc
+import asyncio
+from datetime import timedelta
+import logging
+from contextlib import AbstractAsyncContextManager, AsyncExitStack
+from pathlib import Path
+from typing import Any, Literal
+
+from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
+from mcp import ClientSession, StdioServerParameters, Tool as MCPTool, stdio_client
+from mcp.client.sse import sse_client
+from mcp.client.streamable_http import GetSessionIdCallback, streamablehttp_client
+from mcp.shared.session import ProgressFnT
+from mcp.types import CallToolResult, JSONRPCMessage, InitializeResult
+from mcp.shared.message import SessionMessage
+from typing_extensions import NotRequired, TypedDict
+
+
+class MCPServer(abc.ABC):
+    """Base class for Model Context Protocol servers."""
+
+    @abc.abstractmethod
+    async def connect(self):
+        """Connect to the server. For example, this might mean spawning a subprocess or
+        opening a network connection. The server is expected to remain connected until
+        `cleanup()` is called.
+        """
+        pass
+
+    @property
+    @abc.abstractmethod
+    def name(self) -> str:
+        """A readable name for the server."""
+        pass
+
+    @abc.abstractmethod
+    async def cleanup(self):
+        """Cleanup the server. For example, this might mean closing a subprocess or
+        closing a network connection.
+        """
+        pass
+
+    @abc.abstractmethod
+    async def list_tools(self) -> list[MCPTool]:
+        """List the tools available on the server."""
+        pass
+
+    @abc.abstractmethod
+    async def call_tool(self, tool_name: str, arguments: dict[str, Any] | None) -> CallToolResult:
+        """Invoke a tool on the server."""
+        pass
+
+
+class _MCPServerWithClientSession(MCPServer, abc.ABC):
+    """Base class for MCP servers that use a `ClientSession` to communicate with the server."""
+
+    #def __init__(self, cache_tools_list: bool, session_connect_timeout_seconds: int = 120):
+    def __init__(self, cache_tools_list: bool, client_session_timeout_seconds: float | None):
+        """
+        Args:
+            cache_tools_list: Whether to cache the tools list. If `True`, the tools list will be
+            cached and only fetched from the server once. If `False`, the tools list will be
+            fetched from the server on each call to `list_tools()`. The cache can be invalidated
+            by calling `invalidate_tools_cache()`. You should set this to `True` if you know the
+            server will not change its tools list, because it can drastically improve latency
+            (by avoiding a round-trip to the server every time).
+
+            #session_connect_timeout_seconds: session connect timeout seconds
+            client_session_timeout_seconds: the read timeout passed to the MCP ClientSession.
+        """
+        self.session: ClientSession | None = None
+        self.exit_stack: AsyncExitStack = AsyncExitStack()
+        self._cleanup_lock: asyncio.Lock = asyncio.Lock()
+        self.cache_tools_list = cache_tools_list
+        self.server_initialize_result: InitializeResult | None = None
+        #self.session_connect_timeout_seconds = timedelta(seconds=session_connect_timeout_seconds)
+        self.client_session_timeout_seconds = client_session_timeout_seconds
+
+        # The cache is always dirty at startup, so that we fetch tools at least once
+        self._cache_dirty = True
+        self._tools_list: list[MCPTool] | None = None
+
+    @abc.abstractmethod
+    def create_streams(
+        self,
+    ) -> AbstractAsyncContextManager[
+        tuple[
+            MemoryObjectReceiveStream[SessionMessage | Exception],
+            MemoryObjectSendStream[SessionMessage],
+            GetSessionIdCallback | None
+        ]
+    ]:
+        """Create the streams for the server."""
+        pass
+    # def create_streams(
+    #         self,
+    # ) -> AbstractAsyncContextManager[
+    #     tuple[
+    #         MemoryObjectReceiveStream[JSONRPCMessage | Exception],
+    #         MemoryObjectSendStream[JSONRPCMessage],
+    #     ]
+    # ]:
+    #     """Create the streams for the server."""
+    #     pass
+
+    async def __aenter__(self):
+        await self.connect()
+        return self
+
+    async def __aexit__(self, exc_type, exc_value, traceback):
+        await self.cleanup()
+
+    def invalidate_tools_cache(self):
+        """Invalidate the tools cache."""
+        self._cache_dirty = True
+
+    async def connect(self):
+        """Connect to the server."""
+        try:
+            transport = await self.exit_stack.enter_async_context(self.create_streams())
+            # streamablehttp_client returns (read, write, get_session_id)
+            # sse_client returns (read, write)
+
+            read, write, *_ = transport
+
+            session = await self.exit_stack.enter_async_context(
+                ClientSession(
+                    read,
+                    write,
+                    timedelta(seconds=self.client_session_timeout_seconds)
+                    if self.client_session_timeout_seconds
+                    else None,
+                )
+            )
+            server_result = await session.initialize()
+            self.server_initialize_result = server_result
+            self.session = session
+        except Exception as e:
+            logging.error(f"Error initializing MCP server: {e}")
+            await self.cleanup()
+            return
+        except BaseException as e:
+            logging.error(f"Error initializing MCP server: {e}")
+            await self.cleanup()
+            return
+
+    async def list_tools(self) -> list[MCPTool]:
+        """List the tools available on the server."""
+        if not self.session:
+            raise RuntimeError("Server not initialized. Make sure you call `connect()` first.")
+
+        # Return from cache if caching is enabled, we have tools, and the cache is not dirty
+        if self.cache_tools_list and not self._cache_dirty and self._tools_list:
+            return self._tools_list
+
+        # Reset the cache dirty to False
+        self._cache_dirty = False
+
+        # Fetch the tools from the server
+        self._tools_list = (await self.session.list_tools()).tools
+        return self._tools_list
+
+    # async def call_tool(self, tool_name: str, arguments: dict[str, Any] | None) -> CallToolResult:
+    #     """Invoke a tool on the server."""
+    #     if not self.session:
+    #         raise RuntimeError("Server not initialized. Make sure you call `connect()` first.")
+    #
+    #     return await self.session.call_tool(tool_name, arguments)
+
+    async def call_tool(self, tool_name: str, arguments: dict[str, Any] | None,read_timeout_seconds: timedelta | None = None,progress_callback: ProgressFnT | None = None) -> CallToolResult:
+        """Invoke a tool on the server."""
+        if not self.session:
+            raise RuntimeError("Server not initialized. Make sure you call `connect()` first.")
+        return await self.session.call_tool(name=tool_name, arguments=arguments,read_timeout_seconds=read_timeout_seconds,progress_callback=progress_callback)
+
+    async def cleanup(self):
+        """Cleanup the server."""
+        async with self._cleanup_lock:
+            try:
+                # Ensure cleanup operations occur in the same task context
+                session = self.session
+                self.session = None  # Remove reference first
+
+                # Wait briefly to ensure any pending operations complete
+                try:
+                    await asyncio.sleep(0.1)
+                except asyncio.CancelledError:
+                    # Ignore cancellation exceptions, continue cleaning resources
+                    pass
+
+                # Clean up exit_stack, ensuring all resources are properly closed
+                exit_stack = self.exit_stack
+                if exit_stack:
+                    try:
+                        await exit_stack.aclose()
+                    except Exception as e:
+                        logging.debug(f"Error closing exit stack during cleanup: {e}")
+            except Exception as e:
+                logging.error(f"Error during server cleanup: {e}")
+            finally:
+                self.session = None
+
+
+class MCPServerStdioParams(TypedDict):
+    """Mirrors `mcp.client.stdio.StdioServerParameters`, but lets you pass params without another
+    import.
+    """
+
+    command: str
+    """The executable to run to start the server. For example, `python` or `node`."""
+
+    args: NotRequired[list[str]]
+    """Command line args to pass to the `command` executable. For example, `['foo.py']` or
+    `['server.js', '--port', '4242']`."""
+
+    env: NotRequired[dict[str, str]]
+    """The environment variables to set for the server. ."""
+
+    cwd: NotRequired[str | Path]
+    """The working directory to use when spawning the process."""
+
+    encoding: NotRequired[str]
+    """The text encoding used when sending/receiving messages to the server. Defaults to `utf-8`."""
+
+    encoding_error_handler: NotRequired[Literal["strict", "ignore", "replace"]]
+    """The text encoding error handler. Defaults to `strict`.
+
+    See https://docs.python.org/3/library/codecs.html#codec-base-classes for
+    explanations of possible values.
+    """
+
+    client_session_timeout_seconds: NotRequired[float]
+
+
+class MCPServerStdio(_MCPServerWithClientSession):
+    """MCP server implementation that uses the stdio transport. See the [spec]
+    (https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/transports/#stdio) for
+    details.
+    """
+
+    def __init__(
+            self,
+            params: MCPServerStdioParams,
+            cache_tools_list: bool = False,
+            name: str | None = None,
+            client_session_timeout_seconds: float | None = 120,
+    ):
+        """Create a new MCP server based on the stdio transport.
+
+        Args:
+            params: The params that configure the server. This includes the command to run to
+                start the server, the args to pass to the command, the environment variables to
+                set for the server, the working directory to use when spawning the process, and
+                the text encoding used when sending/receiving messages to the server.
+            cache_tools_list: Whether to cache the tools list. If `True`, the tools list will be
+                cached and only fetched from the server once. If `False`, the tools list will be
+                fetched from the server on each call to `list_tools()`. The cache can be
+                invalidated by calling `invalidate_tools_cache()`. You should set this to `True`
+                if you know the server will not change its tools list, because it can drastically
+                improve latency (by avoiding a round-trip to the server every time).
+            name: A readable name for the server. If not provided, we'll create one from the
+                command.
+             client_session_timeout_seconds: the read timeout passed to the MCP ClientSession.
+        """
+       # super().__init__(cache_tools_list, int(params.get("env").get("SESSION_REQUEST_CONNECT_TIMEOUT", "60")))
+        if params and params.get("client_session_timeout_seconds"):
+            client_session_timeout_seconds = params.get("client_session_timeout_seconds")
+        super().__init__(cache_tools_list, client_session_timeout_seconds)
+
+        self.params = StdioServerParameters(
+            command=params["command"],
+            args=params.get("args", []),
+            env=params.get("env"),
+            cwd=params.get("cwd"),
+            encoding=params.get("encoding", "utf-8"),
+            encoding_error_handler=params.get("encoding_error_handler", "strict"),
+        )
+
+        self._name = name or f"stdio: {self.params.command}"
+
+    def create_streams(
+            self,
+    ) -> AbstractAsyncContextManager[
+        tuple[
+            MemoryObjectReceiveStream[SessionMessage | Exception],
+            MemoryObjectSendStream[SessionMessage],
+            GetSessionIdCallback | None
+        ]
+    ]:
+        """Create the streams for the server."""
+        return stdio_client(self.params)
+
+    @property
+    def name(self) -> str:
+        """A readable name for the server."""
+        return self._name
+
+
+class MCPServerSseParams(TypedDict):
+    """Mirrors the params in`mcp.client.sse.sse_client`."""
+
+    url: str
+    """The URL of the server."""
+
+    headers: NotRequired[dict[str, str]]
+    """The headers to send to the server."""
+
+    timeout: NotRequired[float]
+    """The timeout for the HTTP request. Defaults to 60 seconds."""
+
+    sse_read_timeout: NotRequired[float]
+    """The timeout for the SSE connection, in seconds. Defaults to 5 minutes."""
+
+    client_session_timeout_seconds: NotRequired[float]
+
+
+class MCPServerSse(_MCPServerWithClientSession):
+    """MCP server implementation that uses the HTTP with SSE transport. See the [spec]
+    (https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/transports/#http-with-sse)
+    for details.
+    """
+
+    def __init__(
+            self,
+            params: MCPServerSseParams,
+            cache_tools_list: bool = False,
+            name: str | None = None,
+            client_session_timeout_seconds: float | None = 120,
+    ):
+        """Create a new MCP server based on the HTTP with SSE transport.
+
+        Args:
+            params: The params that configure the server. This includes the URL of the server,
+                the headers to send to the server, the timeout for the HTTP request, and the
+                timeout for the SSE connection.
+
+            cache_tools_list: Whether to cache the tools list. If `True`, the tools list will be
+                cached and only fetched from the server once. If `False`, the tools list will be
+                fetched from the server on each call to `list_tools()`. The cache can be
+                invalidated by calling `invalidate_tools_cache()`. You should set this to `True`
+                if you know the server will not change its tools list, because it can drastically
+                improve latency (by avoiding a round-trip to the server every time).
+
+            name: A readable name for the server. If not provided, we'll create one from the
+                URL.
+             client_session_timeout_seconds: the read timeout passed to the MCP ClientSession.
+        """
+        #super().__init__(cache_tools_list)
+        if params and params.get("client_session_timeout_seconds"):
+            client_session_timeout_seconds = params.get("client_session_timeout_seconds")
+        super().__init__(cache_tools_list, client_session_timeout_seconds)
+
+        self.params = params
+        self._name = name or f"sse: {self.params['url']}"
+
+    def create_streams(
+            self,
+    ) -> AbstractAsyncContextManager[
+        tuple[
+            MemoryObjectReceiveStream[SessionMessage | Exception],
+            MemoryObjectSendStream[SessionMessage],
+            GetSessionIdCallback | None
+        ]
+    ]:
+        """Create the streams for the server."""
+        return sse_client(
+            url=self.params["url"],
+            headers=self.params.get("headers", None),
+            timeout=self.params.get("timeout", 60),
+            sse_read_timeout=self.params.get("sse_read_timeout", 60 * 5),
+        )
+
+    @property
+    def name(self) -> str:
+        """A readable name for the server."""
+        return self._name
+
+
+class MCPServerStreamableHttpParams(TypedDict):
+    """Mirrors the params in`mcp.client.streamable_http.streamablehttp_client`."""
+
+    url: str
+    """The URL of the server."""
+
+    headers: NotRequired[dict[str, str]]
+    """The headers to send to the server."""
+
+    timeout: NotRequired[timedelta]
+    """The timeout for the HTTP request. Defaults to 5 seconds."""
+
+    sse_read_timeout: NotRequired[timedelta]
+    """The timeout for the SSE connection, in seconds. Defaults to 5 minutes."""
+
+    terminate_on_close: NotRequired[bool]
+    """Terminate on close"""
+
+    client_session_timeout_seconds: NotRequired[float]
+
+class MCPServerStreamableHttp(_MCPServerWithClientSession):
+    """MCP server implementation that uses the Streamable HTTP transport. See the [spec]
+    (https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http)
+    for details.
+    """
+
+    def __init__(
+        self,
+        params: MCPServerStreamableHttpParams,
+        cache_tools_list: bool = False,
+        name: str | None = None,
+        client_session_timeout_seconds: float | None = 120,
+    ):
+        """Create a new MCP server based on the Streamable HTTP transport.
+
+        Args:
+            params: The params that configure the server. This includes the URL of the server,
+                the headers to send to the server, the timeout for the HTTP request, and the
+                timeout for the Streamable HTTP connection and whether we need to
+                terminate on close.
+
+            cache_tools_list: Whether to cache the tools list. If `True`, the tools list will be
+                cached and only fetched from the server once. If `False`, the tools list will be
+                fetched from the server on each call to `list_tools()`. The cache can be
+                invalidated by calling `invalidate_tools_cache()`. You should set this to `True`
+                if you know the server will not change its tools list, because it can drastically
+                improve latency (by avoiding a round-trip to the server every time).
+
+            name: A readable name for the server. If not provided, we'll create one from the
+                URL.
+
+            client_session_timeout_seconds: the read timeout passed to the MCP ClientSession.
+        """
+        if params and params.get("client_session_timeout_seconds"):
+            client_session_timeout_seconds = params.get("client_session_timeout_seconds")
+        super().__init__(cache_tools_list, client_session_timeout_seconds)
+
+        self.params = params
+        self._name = name or f"streamable_http: {self.params['url']}"
+
+    def create_streams(
+        self,
+    ) -> AbstractAsyncContextManager[
+        tuple[
+            MemoryObjectReceiveStream[SessionMessage | Exception],
+            MemoryObjectSendStream[SessionMessage],
+            GetSessionIdCallback | None
+        ]
+    ]:
+        """Create the streams for the server."""
+        return streamablehttp_client(
+            url=self.params["url"],
+            headers=self.params.get("headers", None),
+            timeout=self.params.get("timeout", timedelta(seconds=30)),
+            sse_read_timeout=self.params.get("sse_read_timeout", timedelta(seconds=60 * 5)),
+            terminate_on_close=self.params.get("terminate_on_close", True)
+        )
+
+    @property
+    def name(self) -> str:
+        """A readable name for the server."""
+        return self._name
+