ext-apps/examples/basic-server-react/server.ts
Jonathan Hefner 8bb58f332a Update MIME type to text/html;profile=mcp-app
Apply MIME type change from commit 0af1532 to all examples and docs.
The profile parameter follows RFC 6838 recommendations for custom
media types, as MCP Apps is a profile of HTML rather than a new syntax.

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

Co-Authored-By: Claude <noreply@anthropic.com>
2025-12-04 14:50:30 -06:00

104 lines
2.9 KiB
TypeScript

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import type { CallToolResult, ReadResourceResult } from "@modelcontextprotocol/sdk/types.js";
import cors from "cors";
import express, { type Request, type Response } from "express";
import fs from "node:fs/promises";
import path from "node:path";
import { z } from "zod";
import { RESOURCE_URI_META_KEY } from "../../dist/src/app";
const PORT = process.env.PORT ? parseInt(process.env.PORT, 10) : 3001;
const DIST_DIR = path.join(import.meta.dirname, "dist");
const server = new McpServer({
name: "MCP App Server",
version: "1.0.0",
});
// MCP Apps require two-part registration: a tool (what the LLM calls) and a
// resource (the UI it renders). The `_meta` field on the tool links to the
// resource URI, telling hosts which UI to display when the tool executes.
{
const resourceUri = "ui://get-time/mcp-app.html";
server.registerTool(
"get-time",
{
title: "Get Time",
description: "Returns the current server time as an ISO 8601 string.",
inputSchema: {},
outputSchema: { time: z.string() },
_meta: { [RESOURCE_URI_META_KEY]: resourceUri },
},
async (): Promise<CallToolResult> => {
const time = new Date().toISOString();
return {
content: [{ type: "text", text: time }],
structuredContent: { time },
};
},
);
server.registerResource(
resourceUri,
resourceUri,
{},
async (): Promise<ReadResourceResult> => {
const html = await fs.readFile(path.join(DIST_DIR, "mcp-app.html"), "utf-8");
return {
contents: [
// Per the MCP App specification, "text/html;profile=mcp-app" signals
// to the Host that this resource is indeed for an MCP App UI.
{ uri: resourceUri, mimeType: "text/html;profile=mcp-app", text: html },
],
};
},
);
}
const app = express();
app.use(cors());
app.use(express.json());
app.post("/mcp", async (req: Request, res: Response) => {
try {
const transport = new StreamableHTTPServerTransport({
sessionIdGenerator: undefined,
enableJsonResponse: true,
});
res.on("close", () => { transport.close(); });
await server.connect(transport);
await transport.handleRequest(req, res, req.body);
} catch (error) {
console.error("Error handling MCP request:", error);
if (!res.headersSent) {
res.status(500).json({
jsonrpc: "2.0",
error: { code: -32603, message: "Internal server error" },
id: null,
});
}
}
});
const httpServer = app.listen(PORT, () => {
console.log(`Server listening on http://localhost:${PORT}/mcp`);
});
function shutdown() {
console.log("\nShutting down...");
httpServer.close(() => {
console.log("Server closed");
process.exit(0);
});
}
process.on("SIGINT", shutdown);
process.on("SIGTERM", shutdown);