Example doesnt work

[FantixX]

import 'dart:io';

import 'package:udp/udp.dart';

void main() async {
  var sender = await UDP.bind(Endpoint.any(port: Port(65000)));

  // send a simple string to a broadcast endpoint on port 65001.
  var dataLength = await sender.send(
      "Hello World!".codeUnits, Endpoint.broadcast(port: Port(65001)));

  stdout.write("$dataLength bytes sent.");

  // creates a new UDP instance and binds it to the local address and the port
  // 65002.
  var receiver = await UDP.bind(Endpoint.loopback(port: Port(65002)));

  // receiving\listening
  receiver.asStream(timeout: Duration(seconds: 20)).listen((datagram) {
    print("received something");
    var str = String.fromCharCodes(datagram!.data);
    stdout.write(str);
  });

  // close the UDP instances and their sockets.
  sender.close();
  receiver.close();
}

only output: 12 bytes sent.

[jayllfilebyte]

I encountered the same problem.

After a few minute's work, I edited the code and this is my code below:

Future<void> udp() async {
  var sender = await UDP.bind(Endpoint.loopback(port: const Port(65000)));

  // creates a new UDP instance and binds it to the local address and the port
  // 65001.
  var receiver = await UDP.bind(Endpoint.loopback(port: const Port(65001)));

  // receiving\listening
  receiver.asStream(timeout: const Duration(seconds: 20)).listen((datagram) {
    if (kDebugMode) {
      print("received something");
    }
    var str = String.fromCharCodes(datagram!.data);
    if (kDebugMode) {
      print(str);
    }
  });

  // send a simple string to a loopback endpoint on port 65001.
  var dataLength = await sender.send(
      "Hello World!".codeUnits, Endpoint.loopback(port: const Port(65001)));

  if (kDebugMode) {
    print("$dataLength bytes sent.");
  }

  // close the UDP instances and their sockets.
  // sender.close();
  // receiver.close();
}

Output:

flutter: 12 bytes sent.
flutter: received something
flutter: Hello World!

I am using Dart to build Flutter app for both mobile and desktop devices, so I replaced the stdout.write to print.

I guess there are three main reasons why the example code doesn't work:

1. The port the sender send the data to(65001) was different from the port of receiver(65002).
2. The receiver started to listening messages after the sender sent the data. This could cause a data loss.
3. The receiver was closed at the end, which may led to a cancellation when receiving data.

We should close the sender and the receiver manually when they finish their work at a suitable time.