simple-example.js•9.93 kB
#!/usr/bin/env node
/**
* Simple MCP Host Example
*
* This example demonstrates the core functionality:
* 1. Creating an MCP host with context-based authentication
* 2. Registering tools with the new API
* 3. Generating MCP server configurations
*/
import { createMcpHost } from "../dist/host.js";
console.log("🚀 MCP Host Example - Core Functionality\n");
// Create and auto-start the host
const host = createMcpHost({
secret: "example-secret-key-12345",
start: true,
debug: true,
});
// Register an addition tool
host.registerTool(
"add",
{
title: "Add Numbers",
description: "Add two numbers together",
functionName: "addNumbers",
inputSchema: {
type: "object",
properties: {
a: { type: "number", description: "First number" },
b: { type: "number", description: "Second number" },
},
required: ["a", "b"],
additionalProperties: false,
},
},
async (context, args) => {
console.log(`[Handler] Addition called with context:`, context);
console.log(`[Handler] Adding ${args.a} + ${args.b}`);
const result = args.a + args.b;
return {
result: result,
calculation: `${args.a} + ${args.b} = ${result}`,
user: context.userId,
timestamp: new Date().toISOString(),
};
}
);
// Register an echo tool
host.registerTool(
"echo",
{
title: "Echo Message",
description: "Echo a message with context information",
functionName: "echoMessage",
inputSchema: {
type: "object",
properties: {
message: { type: "string", description: "Message to echo" },
},
required: ["message"],
additionalProperties: false,
},
},
async (context, args) => {
console.log(`[Handler] Echo called with context:`, context);
return {
echo: args.message,
user: context.userId,
permissions: context.permissions,
timestamp: new Date().toISOString(),
};
}
);
// Shutdown handling
let isShuttingDown = false;
let mainTimeout;
async function gracefulShutdown() {
if (isShuttingDown) {
console.log("⏳ Shutdown already in progress...");
return;
}
isShuttingDown = true;
console.log("\n🛑 Shutting down gracefully...");
// Clear any pending timers
if (mainTimeout) clearTimeout(mainTimeout);
// Set force exit timeout
const forceExitTimeout = setTimeout(() => {
console.log("⚠️ Force exit timeout reached!");
process.exit(1);
}, 3000); // 3 second force exit
try {
await host.stop();
console.log("✅ Server stopped successfully");
} catch (error) {
console.error("❌ Error during shutdown:", error);
}
clearTimeout(forceExitTimeout);
console.log("✨ Example completed successfully!");
process.exit(0);
}
// Wait for server to start, then demonstrate actual tool execution
mainTimeout = setTimeout(async () => {
try {
console.log("\n🧪 Testing JWT Context-Based Tool Execution...\n");
// Generate different user contexts
const userEnvVars = host.getMCPServerEnvVars(["add", "echo"], {
userId: "user-123",
role: "user",
permissions: ["read", "calculate"],
});
const adminEnvVars = host.getMCPServerEnvVars(["add", "echo"], {
userId: "admin",
role: "admin",
permissions: ["read", "write", "admin", "calculate"],
});
console.log("🔑 JWT Tokens Generated:");
console.log(`User Token: ${userEnvVars.CONTEXT_TOKEN.substring(0, 50)}...`);
console.log(
`Admin Token: ${adminEnvVars.CONTEXT_TOKEN.substring(0, 50)}...`
);
// Test actual tool execution with context
try {
const { JSONRPCClient } = await import("json-rpc-2.0");
const net = await import("net");
// Connect to our host's RPC server
const socket = net.createConnection(userEnvVars.PIPE);
let isConnected = false;
await new Promise((resolve, reject) => {
const cleanup = () => {
if (isConnected) {
socket.destroy();
isConnected = false;
}
};
// Set connection timeout
const connectionTimeout = setTimeout(() => {
cleanup();
reject(new Error("Connection timeout"));
}, 5000);
socket.on("connect", async () => {
isConnected = true;
clearTimeout(connectionTimeout);
console.log("\n✅ Connected to RPC server");
const send = (data) => {
if (socket.writable) {
socket.write(JSON.stringify(data) + "\n");
}
};
const rpcClient = new JSONRPCClient(send);
// Handle incoming data
socket.on("data", (data) => {
const lines = data
.toString()
.split("\n")
.filter((line) => line.trim());
for (const line of lines) {
try {
const response = JSON.parse(line);
rpcClient.receive(response);
} catch (error) {
console.log("Failed to parse response:", line);
}
}
});
try {
// Test 1: Addition tool with user context
console.log("\n🧮 Test 1: Addition Tool (User Context)");
console.log(
" Context: userId=user-123, permissions=[read,calculate]"
);
console.log(" Calling: addNumbers(15, 27)");
const userAddResult = await rpcClient.request("addNumbers", [
userEnvVars.CONTEXT_TOKEN,
{ a: 15, b: 27 },
]);
console.log(
" ✅ Result:",
JSON.stringify(userAddResult, null, 4)
);
// Test 2: Echo tool with user context
console.log("\n📢 Test 2: Echo Tool (User Context)");
console.log(
" Context: userId=user-123, permissions=[read,calculate]"
);
console.log(" Calling: echoMessage('Hello from user context!')");
const userEchoResult = await rpcClient.request("echoMessage", [
userEnvVars.CONTEXT_TOKEN,
{ message: "Hello from user context!" },
]);
console.log(
" ✅ Result:",
JSON.stringify(userEchoResult, null, 4)
);
// Test 3: Same tools with admin context
console.log("\n👑 Test 3: Addition Tool (Admin Context)");
console.log(
" Context: userId=admin, permissions=[read,write,admin,calculate]"
);
console.log(" Calling: addNumbers(100, 200)");
const adminAddResult = await rpcClient.request("addNumbers", [
adminEnvVars.CONTEXT_TOKEN,
{ a: 100, b: 200 },
]);
console.log(
" ✅ Result:",
JSON.stringify(adminAddResult, null, 4)
);
console.log(
"\n🎉 All tools executed successfully with context verification!"
);
cleanup();
resolve();
} catch (error) {
console.error("❌ RPC Error:", error);
cleanup();
reject(error);
}
});
socket.on("error", (error) => {
cleanup();
reject(error);
});
socket.on("close", () => {
cleanup();
});
});
// Show the generated MCP configs
console.log("\n📋 Generated MCP Server Configurations:\n");
const userConfig = host.getMCPServerConfig("user-server", ["add"], {
userId: "user-123",
role: "user",
permissions: ["read", "calculate"],
});
const adminConfig = host.getMCPServerConfig(
"admin-server",
["add", "echo"],
{
userId: "admin",
role: "admin",
permissions: ["read", "write", "admin", "calculate"],
}
);
console.log("👤 User Config (limited to addition tool):");
console.log(JSON.stringify(userConfig, null, 2));
console.log("\n👑 Admin Config (all tools):");
console.log(JSON.stringify(adminConfig, null, 2));
console.log("\n💡 Key Features Demonstrated:");
console.log(" ✅ JWT context-based authentication");
console.log(
" ✅ Tool registration: registerTool(name, properties, handler)"
);
console.log(" ✅ Handler signature: async (context, args) => {}");
console.log(" ✅ Automatic JWT verification and context extraction");
console.log(" ✅ User-scoped tool execution with verified context");
console.log(" ✅ Different contexts for different users/roles");
console.log(" ✅ MCP server config generation");
console.log(" ✅ Tool subsets per user role");
console.log(" ✅ Ready for claude_desktop_config.json");
console.log("\n🎯 Next Steps:");
console.log(
" 1. Copy the MCP config to your claude_desktop_config.json"
);
console.log(" 2. Start Claude Desktop");
console.log(
" 3. The tools will be available with context-based scoping!"
);
} catch (error) {
console.error("❌ Failed to test tools:", error);
}
// Schedule graceful shutdown
setTimeout(gracefulShutdown, 2000);
} catch (error) {
console.error("❌ Example failed:", error);
await gracefulShutdown();
}
}, 1000);
// Graceful shutdown handlers
process.on("SIGINT", gracefulShutdown);
process.on("SIGTERM", gracefulShutdown);
// Handle uncaught exceptions
process.on("uncaughtException", (error) => {
console.error("💥 Uncaught exception:", error);
gracefulShutdown();
});
process.on("unhandledRejection", (reason, promise) => {
console.error("💥 Unhandled rejection at:", promise, "reason:", reason);
gracefulShutdown();
});