Zeroconf

Zeroconf is a simple Java implementation of Multicast DNS Service Discovery, aka the service discovery bit of Zeroconf. Originally written as a quick hack to avoid having to use https://github.com/jmdns/jmdns, it has evolved into something that can both announce and listen for Services on multiple interfaces (IPv4 and IPv6), including properly dealing with changes to those interfaces.

• Requires Java 11+ and no other dependencies.
• Javadocs at https://faceless2.github.io/zeroconf/docs
• Prebuilt binary at https://faceless2.github.io/zeroconf/dist/zeroconf-1.0.jar

Here's a simple example for announcing:

import com.bfo.zeroconf.*;

Zeroconf zc = new Zeroconf();
Service service = new Service.Builder()
                    .setName("MyWeb")
                    .setType("_http._tcp")
                    .setPort(8080)
                    .put("path", "/path/toservice")
                    .build(zc);
service.announce();
// time passes
service.cancel();
// time passes
zc.close();

And to listen, either add a Listener for events, or use the live, thread-safe Collection of Services.

import com.bfo.zeroconf.*;

Zeroconf zc = new Zeroconf();
zc.addListener(new ZeroconfListener() {
    public void serviceNamed(String type, String name) {
        if ("_http._tcp.local".equals(type)) {
            zc.query(type, name);  // Ask for details on any announced HTTP services
        }
    }
    public void serviceAnnounced(Service service) {
        // A new service has just been announced
    }
});

zc.query("_http._tcp.local", null); // Ask for any HTTP services
// time passes

for (Service s : zc.getServices()) {
  if (s.getType().equals("_http._tcp") {
     // A service has been announced at some point in the past, and has not yet expired.
   }
}

// time passes
zc.close();

To build

Run ant to build the Jar in the build directry, and javadoc in the doc directory.