サブスクリプション

from mcp.server.mcpserver import Context, MCPServer

mcp = MCPServer("Sprint Board")

BOARDS = {
    "sprint": {"design": False, "build": False, "ship": False},
    "backlog": {"tidy docs": False},
}


@mcp.resource("board://{name}")
def board(name: str) -> str:
    tasks = BOARDS[name]
    return "\n".join(f"[{'x' if done else ' '}] {task}" for task, done in tasks.items())


@mcp.tool()
async def complete_task(board: str, task: str, ctx: Context) -> str:
    BOARDS[board][task] = True
    await ctx.notify_resource_updated(f"board://{board}")
    return f"{task}: done"


def sprint_report() -> str:
    done = sum(done for tasks in BOARDS.values() for done in tasks.values())
    return f"{done} task(s) done"


@mcp.tool()
async def enable_reports(ctx: Context) -> str:
    mcp.add_tool(sprint_report)
    await ctx.notify_tools_changed()
    return "reporting is live"

from mcp_types import INVALID_REQUEST, SubscriptionsListenRequestParams

from mcp.server.auth.middleware.auth_context import get_access_token
from mcp.server.context import CallNext, HandlerResult, ServerRequestContext
from mcp.server.mcpserver import MCPServer
from mcp.shared.exceptions import MCPError

# Who may see each file. Replace this table with a database or your RBAC system.
ACCESS = {
    "files://report.pdf": {"alice", "bob"},
    "files://payroll.csv": {"carol"},
}


def can_access(user: str | None, uri: str) -> bool:
    return user is not None and user in ACCESS.get(uri, set())


async def gate_subscriptions(ctx: ServerRequestContext, call_next: CallNext) -> HandlerResult:
    if ctx.method == "subscriptions/listen":
        params = SubscriptionsListenRequestParams.model_validate(ctx.params or {}, by_name=False)
        token = get_access_token()
        user = token.subject if token else None
        if not all(can_access(user, uri) for uri in params.notifications.resource_subscriptions or ()):
            raise MCPError(INVALID_REQUEST, "not permitted to watch the requested resources")
    return await call_next(ctx)


mcp = MCPServer("Reports", middleware=[gate_subscriptions])


@mcp.resource("files://{name}")
def file(name: str) -> str:
    uri = f"files://{name}"
    token = get_access_token()
    if not can_access(token.subject if token else None, uri):
        raise MCPError(INVALID_REQUEST, f"Unknown resource: {uri}")
    return f"contents of {name}"

from mcp import Client
from mcp.client.subscriptions import ResourceUpdated, ToolsListChanged
from mcp.types import TextResourceContents

BOARD = "board://sprint"


async def read_board(client: Client, uri: str = BOARD) -> str:
    [contents] = (await client.read_resource(uri)).contents
    assert isinstance(contents, TextResourceContents)
    return contents.text


async def follow_board(client: Client) -> None:
    async with client.listen(tools_list_changed=True, resource_subscriptions=[BOARD]) as sub:
        async for event in sub:
            match event:
                case ResourceUpdated(uri=uri):
                    print(await read_board(client, uri))
                case ToolsListChanged():
                    tools = await client.list_tools()
                    print("tools:", [tool.name for tool in tools.tools])
                case _:
                    pass  # kinds the filter did not ask for never arrive


async def main() -> None:
    async with Client("http://localhost:8000/mcp") as client:
        await follow_board(client)

from collections.abc import Callable

from redis.asyncio import Redis

from mcp.server.mcpserver import MCPServer
from mcp.server.subscriptions import ServerEvent  # SubscriptionBus is a Protocol: no base class


class RedisSubscriptionBus:
    def __init__(self, redis: Redis) -> None:
        self._redis = redis
        self._listeners: dict[object, Callable[[ServerEvent], None]] = {}

    async def publish(self, event: ServerEvent) -> None:
        await self._redis.publish("mcp-events", encode(event))  # to every replica

    def subscribe(self, listener: Callable[[ServerEvent], None]) -> Callable[[], None]:
        token = object()
        self._listeners[token] = listener

        def unsubscribe() -> None:
            self._listeners.pop(token, None)

        return unsubscribe


mcp = MCPServer("Sprint Board", subscriptions=RedisSubscriptionBus(redis))

from mcp.server.subscriptions import InMemorySubscriptionBus, ToolsListChanged

bus = InMemorySubscriptionBus()
mcp = MCPServer("Sprint Board", subscriptions=bus)


async def tools_reloaded() -> None:
    await bus.publish(ToolsListChanged())  # from a lifespan task, a webhook, anywhere

from typing import Any

import mcp.types as types
from mcp.server.context import ServerRequestContext
from mcp.server.lowlevel import Server
from mcp.server.subscriptions import InMemorySubscriptionBus, ListenHandler, ResourceUpdated

bus = InMemorySubscriptionBus()
listen_handler = ListenHandler(bus)

BOARD = {"design": False, "build": False}

COMPLETE_TASK_SCHEMA: dict[str, Any] = {
    "type": "object",
    "properties": {"task": {"type": "string"}},
    "required": ["task"],
}


async def read_resource(
    ctx: ServerRequestContext[Any], params: types.ReadResourceRequestParams
) -> types.ReadResourceResult:
    board = "\n".join(f"[{'x' if done else ' '}] {task}" for task, done in BOARD.items())
    return types.ReadResourceResult(contents=[types.TextResourceContents(uri=params.uri, text=board)])


async def list_tools(
    ctx: ServerRequestContext[Any], params: types.PaginatedRequestParams | None
) -> types.ListToolsResult:
    return types.ListToolsResult(
        tools=[types.Tool(name="complete_task", description="Mark a task done.", input_schema=COMPLETE_TASK_SCHEMA)]
    )


async def call_tool(ctx: ServerRequestContext[Any], params: types.CallToolRequestParams) -> types.CallToolResult:
    args = params.arguments or {}
    BOARD[args["task"]] = True
    await bus.publish(ResourceUpdated(uri="board://sprint"))
    return types.CallToolResult(content=[types.TextContent(type="text", text="done")])


server = Server(
    "sprint-board",
    on_read_resource=read_resource,
    on_list_tools=list_tools,
    on_call_tool=call_tool,
    on_subscriptions_listen=listen_handler,
)