Introduction to mdns javascript

What is mdns?

mdns, short for Multicast DNS, is a protocol for resolving hostnames and IP addresses in local networks without the need for a centralized DNS server. It allows devices on the same network to discover and communicate with each other using domain names instead of IP addresses.

mdns in JavaScript

mdns can be implemented in JavaScript using libraries like mdns-js. These libraries provide a convenient way to perform mDNS operations, such as advertising services, browsing and discovering available services, and resolving hostnames to IP addresses.

Installing mdns-js

To use mdns in JavaScript, you first need to install the mdns-js library. You can do this using npm by running the following command:

npm install mdns-js

Example code for mdns-js

Here is an example code snippet showing how to use mdns-js to advertise a service and listen for service discovery:

const mdns = require('mdns-js');

// Create and advertise a service
const ad = mdns.createAdvertisement(mdns.tcp('http'), 3000);
ad.start();

// Browse and discover available services
const browser = mdns.createBrowser(mdns.tcp('http'));
browser.on('serviceUp', (service) => {
  console.log(`Discovered service: ${service.host}:${service.port}`);
});
browser.start();

In the above code, we first create an advertisement for a TCP-based HTTP service on port 3000 using mdns.createAdvertisement() and start advertising it using ad.start().

We then create a browser to discover services using mdns.createBrowser() and listen for the serviceUp event to handle the discovery of available services. In our example, we simply log the discovered service's host and port.

Conclusion

mdns is a powerful protocol for local network service discovery, and implementing it in JavaScript using libraries like mdns-js makes it easy for programmers to take advantage of this functionality. With mdns-js, you can advertise and discover services in your local network, enabling seamless communication between devices.