HttpMcpServer

MCP server over Streamable HTTP using Express. Each HTTP client gets its own session. Extends BaseMcpServer. See src/mcp/mcp-server.ts for the full signature.

constructor(serverInfo)

Parameter	Type	Description
serverInfo	HttpServerInfo	{ name: string; version: string; port: number }

start()

Binds Express to the configured port. Idempotent: subsequent calls are no-ops while the server is already listening.

stop()

Closes all active HTTP sessions (each transport is closed), clears the session map, then stops the Express listener and destroys all remaining connections, including idle keep-alive and open SSE sockets, so the process can shut down and the port is fully released. Idempotent; safe to call when not running.

Request routing (/mcp)

Method	Session ID header	Action
DELETE	present	Disconnect that session
DELETE	missing	404
POST	present	Route to existing session
POST	missing	Create a new session
GET	present	Route to existing session
GET	missing	400
Other	missing	400
Other	present	Route to existing session; the SDK rejects unsupported methods

Lifecycle

1. constructor(info): initialises Express app and wires routes
2. registerTool(item): tools must be registered before start() (they are copied into each per-session McpServer at creation time)
3. start(): begins listening on the configured port
4. Client sends POST /mcp (initialize) → handleCreateSession creates a transport, connects a fresh McpServer (via createFreshMcpServer()), stores the session, forwards the response
5. Subsequent requests include Mcp-Session-Id → routed via handleExistingSession
6. DELETE /mcp → handleDelete removes and closes the session
7. stop() → onStop() snapshots and clears all sessions, closes each transport, then stops Express and destroys any lingering keep-alive/SSE connections

Types

HttpServerInfo

Extends ServerInfo with the TCP port for Express to bind to.

Field	Type	Description
name	string	Server name
version	string	Server version
port	number	TCP port for Express to bind to

---

See also: BaseMcpServer, StdioMcpServer, Architecture, Quick Start