fix(examples): create fresh McpServer per client in three examples#1610
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mattzcarey merged 1 commit intomodelcontextprotocol:mainfrom Mar 2, 2026
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Move McpServer creation and tool/resource registration into a getServer() factory function that is called for each new client connection, matching the pattern used by simpleStreamableHttp and jsonResponseStreamableHttp. Sharing a single McpServer instance across multiple clients can cause issues with concurrent connections. The three updated examples are: - elicitationFormExample.ts - standaloneSseWithGetStreamableHttp.ts - ssePollingExample.ts Fixes modelcontextprotocol#1278
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@modelcontextprotocol/client
@modelcontextprotocol/server
@modelcontextprotocol/express
@modelcontextprotocol/hono
@modelcontextprotocol/node
commit: |
mattzcarey
reviewed
Mar 2, 2026
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| // Close all active transports to properly clean up resources | ||
| for (const sessionId in transports) { | ||
| try { | ||
| console.log(`Closing transport for session ${sessionId}`); | ||
| await transports[sessionId]!.close(); | ||
| delete transports[sessionId]; | ||
| delete servers[sessionId]; | ||
| } catch (error) { | ||
| console.error(`Error closing transport for session ${sessionId}:`, error); | ||
| } | ||
| } |
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this shouldnt be necessary?
mattzcarey
approved these changes
Mar 2, 2026
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Summary
Fixes #1278
Three example files were sharing a single
McpServerinstance across all client connections. This can cause issues when multiple clients connect concurrently, as the server's internal state (tools, resources, sessions) becomes entangled between unrelated clients.This PR updates the following examples to create a fresh
McpServerper client connection using agetServer()factory function, matching the pattern already used bysimpleStreamableHttp.tsandjsonResponseStreamableHttp.ts:elicitationFormExample.ts— WrappedMcpServercreation and all three tool registrations (register_user,create_event,update_shipping_address) intogetServer(), called on each new initialization request.standaloneSseWithGetStreamableHttp.ts— MovedMcpServercreation and initial resource registration intogetServer(). TheaddResourcehelper now takes a server parameter. The periodic resource change interval adds resources to all active server instances. Added proper cleanup of bothtransportsandserversmaps on close/shutdown.ssePollingExample.ts— WrappedMcpServercreation andlong-tasktool registration intogetServer(), called when creating a new transport.Test plan
pnpm build:all)pnpm typecheck:all)pnpm lint:all)