#!/usr/bin/env node
/**
* MCP Client Example
*
* This example demonstrates how to programmatically interact with the Weather MCP Server.
* Use this as a reference for building your own MCP clients or for testing the server.
*
* @author IrisGo.AI
* @version 1.0.0
*/
import { spawn } from 'child_process';
import { fileURLToPath } from 'url';
import { dirname, join } from 'path';
const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);
/**
* Simple MCP Client
*
* Connects to an MCP server via stdio and allows sending requests
*/
class MCPClient {
constructor(serverPath) {
this.serverPath = serverPath;
this.process = null;
this.requestId = 0;
this.pendingRequests = new Map();
}
/**
* Start the MCP server process
*/
async start() {
return new Promise((resolve, reject) => {
console.log('Starting MCP server...');
this.process = spawn('node', [this.serverPath], {
stdio: ['pipe', 'pipe', 'pipe'],
});
let serverReady = false;
// Handle server output
this.process.stdout.on('data', (data) => {
const lines = data.toString().split('\n').filter(line => line.trim());
lines.forEach(line => {
try {
const response = JSON.parse(line);
this.handleResponse(response);
} catch (e) {
console.error('Failed to parse response:', line);
}
});
});
// Handle server errors
this.process.stderr.on('data', (data) => {
const message = data.toString();
console.error('[Server]', message);
if (message.includes('running on stdio')) {
serverReady = true;
resolve();
}
});
this.process.on('error', (error) => {
reject(error);
});
this.process.on('exit', (code) => {
console.log(`Server exited with code ${code}`);
});
// Timeout if server doesn't start
setTimeout(() => {
if (!serverReady) {
reject(new Error('Server failed to start within timeout'));
}
}, 5000);
});
}
/**
* Stop the MCP server
*/
stop() {
if (this.process) {
this.process.kill();
this.process = null;
}
}
/**
* Send a request to the MCP server
*/
async request(method, params = {}) {
return new Promise((resolve, reject) => {
const id = ++this.requestId;
const request = {
jsonrpc: '2.0',
id,
method,
params,
};
// Store the pending request
this.pendingRequests.set(id, { resolve, reject });
// Send to server
this.process.stdin.write(JSON.stringify(request) + '\n');
// Timeout after 10 seconds
setTimeout(() => {
if (this.pendingRequests.has(id)) {
this.pendingRequests.delete(id);
reject(new Error('Request timeout'));
}
}, 10000);
});
}
/**
* Handle response from server
*/
handleResponse(response) {
const { id, result, error } = response;
if (this.pendingRequests.has(id)) {
const { resolve, reject } = this.pendingRequests.get(id);
this.pendingRequests.delete(id);
if (error) {
reject(new Error(error.message || 'Unknown error'));
} else {
resolve(result);
}
}
}
/**
* List available tools
*/
async listTools() {
return this.request('tools/list');
}
/**
* Call a tool
*/
async callTool(name, args) {
return this.request('tools/call', { name, arguments: args });
}
}
/**
* Main test function
*/
async function main() {
const serverPath = join(__dirname, '..', 'index.js');
const client = new MCPClient(serverPath);
try {
// Start server
await client.start();
console.log('✅ Server started successfully\n');
// Test 1: List available tools
console.log('=== Test 1: List Available Tools ===');
const toolsList = await client.listTools();
console.log('Available tools:');
toolsList.tools.forEach(tool => {
console.log(` - ${tool.name}: ${tool.description}`);
});
console.log('✅ Test 1 passed\n');
// Test 2: Get current weather for Taipei
console.log('=== Test 2: Get Current Weather (Taipei) ===');
const taipeiWeather = await client.callTool('get_current_weather', {
city: 'Taipei',
units: 'metric',
});
console.log(taipeiWeather.content[0].text);
console.log('✅ Test 2 passed\n');
// Test 3: Get current weather for New York (imperial units)
console.log('=== Test 3: Get Current Weather (New York, Imperial) ===');
const nyWeather = await client.callTool('get_current_weather', {
city: 'New York',
units: 'imperial',
});
console.log(nyWeather.content[0].text);
console.log('✅ Test 3 passed\n');
// Test 4: Get 5-day forecast for Tokyo
console.log('=== Test 4: Get 5-Day Forecast (Tokyo) ===');
const tokyoForecast = await client.callTool('get_weather_forecast', {
city: 'Tokyo',
units: 'metric',
});
console.log(tokyoForecast.content[0].text);
console.log('✅ Test 4 passed\n');
// Test 5: Error handling - invalid city
console.log('=== Test 5: Error Handling (Invalid City) ===');
try {
await client.callTool('get_current_weather', {
city: 'InvalidCityName12345',
units: 'metric',
});
console.log('❌ Test 5 failed: Should have thrown an error');
} catch (error) {
console.log('Expected error:', error.message);
console.log('✅ Test 5 passed\n');
}
// Test 6: Multiple concurrent requests
console.log('=== Test 6: Concurrent Requests ===');
const cities = ['London', 'Paris', 'Berlin', 'Madrid', 'Rome'];
const startTime = Date.now();
const promises = cities.map(city =>
client.callTool('get_current_weather', { city, units: 'metric' })
);
const results = await Promise.all(promises);
const duration = Date.now() - startTime;
console.log(`Fetched weather for ${cities.length} cities in ${duration}ms`);
results.forEach((result, index) => {
const lines = result.content[0].text.split('\n');
console.log(` ${cities[index]}: ${lines[1]}`); // Print temperature line
});
console.log('✅ Test 6 passed\n');
// Summary
console.log('=== Summary ===');
console.log('✅ All tests passed!');
console.log('MCP server is working correctly.');
} catch (error) {
console.error('❌ Test failed:', error.message);
console.error(error.stack);
process.exit(1);
} finally {
// Clean up
client.stop();
console.log('\nServer stopped.');
}
}
// Run tests if this file is executed directly
if (import.meta.url === `file://${process.argv[1]}`) {
main().catch(console.error);
}
export { MCPClient };
