ext-apps/examples/basic-server-react
Repository files (latest commit first)
Filename Latest commit message Latest commit date
Olivier Chafik 3a30e94501
feat(examples): add SSE transport support and shared server utility (#136)
* feat(examples): add SSE transport support to all example servers

Add backwards-compatible SSE transport support alongside the current
Streamable HTTP transport. Each server now exposes:

- /mcp (GET, POST, DELETE) - Streamable HTTP transport (current spec)
- /sse (GET) - Legacy SSE transport stream endpoint
- /messages (POST) - Legacy SSE transport message endpoint

This enables older clients using the deprecated HTTP+SSE protocol
(version 2024-11-05) to connect to the example servers.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor(examples): migrate 6 servers to use shared server utility

Refactored the following example servers to use the shared startServer utility from examples/shared/server-utils.ts:
- threejs-server
- system-monitor-server
- cohort-heatmap-server
- budget-allocator-server
- customer-segmentation-server
- scenario-modeler-server

Changes for each server:
- Removed direct imports: SSEServerTransport, StdioServerTransport, StreamableHTTPServerTransport, cors, express
- Removed PORT constant (now handled by shared utility)
- Added import for startServer from ../shared/server-utils.js
- Replaced entire async main() function with single startServer() call
- Preserved all business logic (tool registration, resource registration, helper functions)

This reduces code duplication by ~700 lines and ensures consistent transport handling across all example servers.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor(examples): migrate remaining servers to shared utility

Complete the migration of example servers to use the shared
server-utils.ts module for transport setup:

- basic-server-react
- basic-server-vanillajs
- wiki-explorer-server
- Add shared/server-utils.ts

This centralizes all transport handling (stdio, Streamable HTTP, SSE)
in one place, reducing code duplication across ~500 lines.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): improve server-utils with stateful sessions and security

Address critical issues in the shared server utility:

1. Stateful sessions: Use sessionIdGenerator + onsessioninitialized
   to persist StreamableHTTPServerTransport across requests
2. Unified session store: Single Map for both transport types with
   proper type discrimination
3. Error handling: Try/catch on all endpoints with JSON-RPC errors
4. DNS rebinding protection: Use SDK's createMcpExpressApp helper

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): allow connections from any host for development

Use host: "0.0.0.0" in createMcpExpressApp to disable DNS rebinding
protection, allowing connections from Android emulators and other
devices on the network. Also re-add CORS middleware.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor(examples): use getPort() helper for transport selection

- Add getPort() helper that returns undefined for --stdio, else port
- Caller now explicitly passes port to startServer()
- port: undefined → stdio mode, port: number → HTTP mode

This makes the transport selection explicit at the call site.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): startServer returns promise that resolves/rejects on listen

Use httpServer.on('listening') and httpServer.on('error') events
to properly resolve or reject the returned promise.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): add error handling to startServer calls

Exit with code 1 if server fails to start (e.g., port in use).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* refactor(examples): update server files to use main() pattern with stdio support

Update all example server files to use the new main() pattern that supports both HTTP and stdio transports:
- Add StdioServerTransport import
- Remove getPort import (replaced with direct env var parsing)
- Replace direct startServer call with async main() function
- Add --stdio flag detection to choose between transports
- Use PORT env var with default 3001 for HTTP mode

Updated servers:
- basic-server-vanillajs
- wiki-explorer-server
- threejs-server
- system-monitor-server
- cohort-heatmap-server
- budget-allocator-server
- customer-segmentation-server
- scenario-modeler-server

Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): use correct default ports matching run-all.ts

Each server now defaults to its assigned port from run-all.ts:
- basic-server-react: 3101
- basic-server-vanillajs: 3102
- budget-allocator-server: 3103
- cohort-heatmap-server: 3104
- customer-segmentation-server: 3105
- scenario-modeler-server: 3106
- system-monitor-server: 3107
- threejs-server: 3108
- wiki-explorer-server: 3109

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix(examples): expose mcp-session-id header for CORS requests

Without exposedHeaders in the CORS config, browsers block JavaScript
from reading the mcp-session-id response header. This caused the SDK's
StreamableHTTPClientTransport to never capture the session ID, breaking
all subsequent requests with "Bad request: not initialized" errors.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* pretty:fix

---------

Co-authored-by: Claude <noreply@anthropic.com>
2025-12-12 13:10:10 +00:00
..
src feat: implement ui/notifications/tool-cancelled + add missing App.onteardown (#120) 2025-12-11 20:31:17 +01:00
mcp-app.html Add basic-host and basic-server-react examples 2025-12-04 14:28:27 -06:00
package.json Smoothen the process of getting started (#103) 2025-12-09 16:15:32 +01:00
README.md Add basic-server-vanillajs example 2025-12-04 14:28:27 -06:00
server.ts feat(examples): add SSE transport support and shared server utility (#136) 2025-12-12 13:10:10 +00:00
tsconfig.json Add basic-host and basic-server-react examples 2025-12-04 14:28:27 -06:00
vite.config.ts Add basic-host and basic-server-react examples 2025-12-04 14:28:27 -06:00

Example: Basic Server (React)

An MCP App example with a React UI.

Tip

Looking for a vanilla JavaScript example? See basic-server-vanillajs!

Overview

Key Files

Getting Started

npm install
npm run dev

How It Works

  1. The server registers a get-time tool with metadata linking it to a UI HTML resource (ui://get-time/mcp-app.html).
  2. When the tool is invoked, the Host renders the UI from the resource.
  3. The UI uses the MCP App SDK API to communicate with the host and call server tools.