python-sdk/src/mcp/server/session.py at main · devilcoder/python-sdk · GitHub

History

317 lines (280 loc) · 11.2 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

"""

ServerSession Module

This module provides the ServerSession class, which manages communication between the

server and client in the MCP (Model Context Protocol) framework. It is most commonly

used in MCP servers to interact with the client.

Common usage pattern:

```

server = Server(name)

@server.call_tool()

async def handle_tool_call(ctx: RequestContext, arguments: dict[str, Any]) -> Any:

# Check client capabilities before proceeding

if ctx.session.check_client_capability(

types.ClientCapabilities(experimental={"advanced_tools": dict()})

# Perform advanced tool operations

result = await perform_advanced_tool_operation(arguments)

else:

# Fall back to basic tool operations

result = await perform_basic_tool_operation(arguments)

return result

@server.list_prompts()

async def handle_list_prompts(ctx: RequestContext) -> list[types.Prompt]:

# Access session for any necessary checks or operations

if ctx.session.client_params:

# Customize prompts based on client initialization parameters

return generate_custom_prompts(ctx.session.client_params)

else:

return default_prompts

```

The ServerSession class is typically used internally by the Server class and should not

be instantiated directly by users of the MCP framework.

"""

from enum import Enum

from typing import Any, TypeVar

import anyio

import anyio.lowlevel

from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream

from pydantic import AnyUrl

import mcp.types as types

from mcp.server.models import InitializationOptions

from mcp.shared.session import (

BaseSession,

RequestResponder,

)

class InitializationState(Enum):

NotInitialized = 1

Initializing = 2

Initialized = 3

ServerSessionT = TypeVar("ServerSessionT", bound="ServerSession")

ServerRequestResponder = (

RequestResponder[types.ClientRequest, types.ServerResult]

| types.ClientNotification

| Exception

)

class ServerSession(

BaseSession[

types.ServerRequest,

types.ServerNotification,

types.ServerResult,

types.ClientRequest,

types.ClientNotification,

]

_initialized: InitializationState = InitializationState.NotInitialized

_client_params: types.InitializeRequestParams | None = None

def __init__(

self,

read_stream: MemoryObjectReceiveStream[types.JSONRPCMessage | Exception],

write_stream: MemoryObjectSendStream[types.JSONRPCMessage],

init_options: InitializationOptions,

) -> None:

super().__init__(

read_stream, write_stream, types.ClientRequest, types.ClientNotification

)

self._initialization_state = InitializationState.NotInitialized

self._init_options = init_options

self._incoming_message_stream_writer, self._incoming_message_stream_reader = (

anyio.create_memory_object_stream[ServerRequestResponder](0)

)

self._exit_stack.push_async_callback(

lambda: self._incoming_message_stream_reader.aclose()

)

self._exit_stack.push_async_callback(

lambda: self._incoming_message_stream_writer.aclose()

)

@property

def client_params(self) -> types.InitializeRequestParams | None:

return self._client_params

def check_client_capability(self, capability: types.ClientCapabilities) -> bool:

"""Check if the client supports a specific capability."""

if self._client_params is None:

return False

# Get client capabilities from initialization params

client_caps = self._client_params.capabilities

# Check each specified capability in the passed in capability object

if capability.roots is not None:

if client_caps.roots is None:

return False

if capability.roots.listChanged and not client_caps.roots.listChanged:

return False

if capability.sampling is not None:

if client_caps.sampling is None:

return False

if capability.experimental is not None:

if client_caps.experimental is None:

return False

# Check each experimental capability

for exp_key, exp_value in capability.experimental.items():

if (

exp_key not in client_caps.experimental

or client_caps.experimental[exp_key] != exp_value

return False

return True

async def _received_request(

self, responder: RequestResponder[types.ClientRequest, types.ServerResult]

match responder.request.root:

case types.InitializeRequest(params=params):

self._initialization_state = InitializationState.Initializing

self._client_params = params

with responder:

await responder.respond(

types.ServerResult(

types.InitializeResult(

protocolVersion=types.LATEST_PROTOCOL_VERSION,

capabilities=self._init_options.capabilities,

serverInfo=types.Implementation(

name=self._init_options.server_name,

version=self._init_options.server_version,

instructions=self._init_options.instructions,

)

case _:

if self._initialization_state != InitializationState.Initialized:

raise RuntimeError(

"Received request before initialization was complete"

)

async def _received_notification(

self, notification: types.ClientNotification

) -> None:

# Need this to avoid ASYNC910

await anyio.lowlevel.checkpoint()

match notification.root:

case types.InitializedNotification():

self._initialization_state = InitializationState.Initialized

case _:

if self._initialization_state != InitializationState.Initialized:

raise RuntimeError(

"Received notification before initialization was complete"

)

async def send_log_message(

self, level: types.LoggingLevel, data: Any, logger: str | None = None

) -> None:

"""Send a log message notification."""

await self.send_notification(

types.ServerNotification(

types.LoggingMessageNotification(

method="notifications/message",

params=types.LoggingMessageNotificationParams(

level=level,

data=data,

logger=logger,

)

async def send_resource_updated(self, uri: AnyUrl) -> None:

"""Send a resource updated notification."""

await self.send_notification(

types.ServerNotification(

types.ResourceUpdatedNotification(

method="notifications/resources/updated",

params=types.ResourceUpdatedNotificationParams(uri=uri),

)

async def create_message(

self,

messages: list[types.SamplingMessage],

max_tokens: int,

system_prompt: str | None = None,

include_context: types.IncludeContext | None = None,

temperature: float | None = None,

stop_sequences: list[str] | None = None,

metadata: dict[str, Any] | None = None,

model_preferences: types.ModelPreferences | None = None,

) -> types.CreateMessageResult:

"""Send a sampling/create_message request."""

return await self.send_request(

types.ServerRequest(

types.CreateMessageRequest(

method="sampling/createMessage",

params=types.CreateMessageRequestParams(

messages=messages,

systemPrompt=system_prompt,

includeContext=include_context,

temperature=temperature,

maxTokens=max_tokens,

stopSequences=stop_sequences,

metadata=metadata,

modelPreferences=model_preferences,

)

types.CreateMessageResult,

)

async def list_roots(self) -> types.ListRootsResult:

"""Send a roots/list request."""

return await self.send_request(

types.ServerRequest(

types.ListRootsRequest(

method="roots/list",

)

types.ListRootsResult,

)

async def send_ping(self) -> types.EmptyResult:

"""Send a ping request."""

return await self.send_request(

types.ServerRequest(

types.PingRequest(

method="ping",

)

types.EmptyResult,

)

async def send_progress_notification(

self, progress_token: str | int, progress: float, total: float | None = None

) -> None:

"""Send a progress notification."""

await self.send_notification(

types.ServerNotification(

types.ProgressNotification(

method="notifications/progress",

params=types.ProgressNotificationParams(

progressToken=progress_token,

progress=progress,

total=total,

)

async def send_resource_list_changed(self) -> None:

"""Send a resource list changed notification."""

await self.send_notification(

types.ServerNotification(

types.ResourceListChangedNotification(

method="notifications/resources/list_changed",

)

async def send_tool_list_changed(self) -> None:

"""Send a tool list changed notification."""

await self.send_notification(

types.ServerNotification(

types.ToolListChangedNotification(

method="notifications/tools/list_changed",

)

async def send_prompt_list_changed(self) -> None:

"""Send a prompt list changed notification."""

await self.send_notification(

types.ServerNotification(

types.PromptListChangedNotification(

method="notifications/prompts/list_changed",

)

async def _handle_incoming(self, req: ServerRequestResponder) -> None:

await self._incoming_message_stream_writer.send(req)

@property

def incoming_messages(

self,

) -> MemoryObjectReceiveStream[ServerRequestResponder]:

return self._incoming_message_stream_reader

python-sdk/src/mcp/server/session.py at main · devilcoder/python-sdk · GitHub

Expand file tree

Breadcrumbs

session.py

Latest commit

History

Breadcrumbs

session.py

File metadata and controls