mdns_plugin #

Yet another package which discovers network services on the local network. Presently, this package is in development, and should work for iOS targets. Android targets work with one caveat mentioned below.

Please file any issues or feature requests on github, thanks.

Using the plugin #

You use the plugin by calling startDiscovery and stopDiscovery on an instance of MDNSPlugin, which you need to create by passing a delegate instance. The MDNSPlugin class provides two methods and a constructor:

class MDNSPlugin {
    /// Constructor
    MDNSPlugin(MDNSPluginDelegate)

    /// platformVersion returns the underlying platform version of the
    /// running plugin
    static Future<String> get platformVersion async;

    /// startDiscovery is invoked to start discovery of services on
    /// the local network, for a serviceType, which should be, for
    /// example "_googlecast._tcp" or similar. When the optional
    /// enableUpdating flag is set to true, resolved services
    /// respond to updates to the TXT record for the service
    Future<void> startDiscovery(String serviceType,{ bool enableUpdating = false }) async;

    /// stopDiscovery should be invoked to shutdown the discovery
    /// of services on your local network
    Future<void> stopDiscovery() async;
}

One limitation is that on Android, the enableUpdating flag is currently ignored. Future work will correct this to bring the platforms in parity. The delegate instance will receive messages from the plugin. Your delegate class should implement the following methods:

abstract class MDNSPluginDelegate {

  /// onDiscoveryStarted is called when discovery on the local 
  /// network has started
  void onDiscoveryStarted();

  /// onDiscoveryStopped is called when discovery on the local
  /// network has stopped
  void onDiscoveryStopped();

  /// onServiceFound is called when a service on the local network 
  /// has been discovered. Your function implementation should 
  /// return true if you want the service to be resolved
  bool onServiceFound(MDNSService service);

  /// onServiceResolved is called when resolution has occurred,
  /// filling in the details (hostname, addresses, etc) of the
  /// service
  void onServiceResolved(MDNSService service);

  /// onServiceUpdated is called when a found service has updated 
  /// the TXT record
  void onServiceUpdated(MDNSService service);

  /// onServiceRemoved is called when a found service has been
  /// removed from the local network
  void onServiceRemoved(MDNSService service);
}

Example #

Here's a basic example which implements a delegate, that can respond to mDNS services being discovered and updated:

import 'dart:async';
import 'package:mdns_plugin/mdns_plugin.dart';

void main() async {
    MDNSPlugin mdns = new MDNSPlugin(Delegate());
    await mdns.startDiscovery("_googlecast._tcp",enableUpdating: true);
    sleep();
    await mdns.stopDiscovery();
    sleep();
}

Future sleep() {
  return new Future.delayed(const Duration(seconds: 5), () => "5");
}

class Delegate implements MDNSPluginDelegate {
  void onDiscoveryStarted() {
      print("Discovery started");
  }
  void onDiscoveryStopped() {
      print("Discovery stopped");
  }
  bool onServiceFound(MDNSService service) {
      print("Found: $service");
      // Always returns true which begins service resolution
      return true;
  }
  void onServiceResolved(MDNSService service) {
      print("Resolved: $service");
  }
  void onServiceUpdated(MDNSService service) {
      print("Updated: $service");
  }
  void onServiceRemoved(MDNSService service) {
      print("Removed: $service");
  }
}

For a fuller example please see the application in the example folder.

Publishing this plugin #

(Some notes for me) In order to publish the plugin, edit the pubspec.yaml and CHANGELOG.md files in the root directory and the example directory to bump the version number $TAG and then run the following commands:

bash% TAG=v`sed -n 's/version\: \(.*\)/\1/p' pubspec.yaml`
bash% echo $TAG && flutter format .
bash% git commit -a -m "Updated version to $TAG"
bash% git push && git tag $TAG && git push --tags
bash% flutter pub pub publish

You should then merge v1 into the master branch.