nats.ws

import { connect, StringCodec, Empty } from 'nats.ws'; // In a Node.js environment, you might need to shim WebSocket: // globalThis.WebSocket = require('websocket').w3cwebsocket; async function runNatsClient() { const servers = process.env.NATS_SERVER_URL ?? 'ws://localhost:9222'; console.log(`Connecting to NATS server at: ${servers}`); try { const nc = await connect({ servers: servers }); const sc = StringCodec.create(); console.log(`Connected to ${nc.getServer()}`); // Subscribe to a subject and respond to requests const sub = nc.subscribe('time.requests'); (async () => { for await (const m of sub) { const requestPayload = sc.decode(m.data); const response = `Current time for '${requestPayload}': ${new Date().toLocaleTimeString()}`; m.respond(sc.encode(response)); console.log(`[time.requests] received: '${requestPayload}' and responded with: '${response}'`); } console.log('Subscription to time.requests closed'); })(); // Publish a message and request a response const requestPayload = 'What time is it in Tokyo?'; const response = await nc.request('time.requests', sc.encode(requestPayload), { timeout: 1000 }); console.log(`[time.requests] received response: ${sc.decode(response.data)}`); // Publish a simple message nc.publish('hello', sc.encode('world')); console.log('Published "hello world" to subject "hello"'); await nc.flush(); // Ensure all messages are sent await nc.close(); console.log('Connection closed.'); } catch (err: any) { console.error(`Error connecting or interacting with NATS: ${err.message}`); if (err.code) { console.error(`NATS Error Code: ${err.code}`); } } } runNatsClient();