play.dart

import 'dart:io';

Future<void> startPlayServer(int port) async {
  HttpServer server = await HttpServer.bind(
    InternetAddress.loopbackIPv4,
    port,
  );
  await for (var request in server) {
    _handleRequest(request);
  }
}

void _handleRequest(HttpRequest request) async {
  try {
    await play();
    await request.response.close();
  } catch (e) {
    print('Exception in _handleRequest');
    print(e);
  }
}

Future<void> play() async {
  print("hello at" + DateTime.now().toIso8601String());
  return null;
}

tasks.json

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "play",
      "type": "shell",
      "command": "curl",
      "args": [
        "http://localhost:9999"
      ],
      "problemMatcher": [],
      "presentation": {
        "echo": true,
        "reveal": "silent",
        "focus": false,
        "panel": "shared",
        "showReuseMessage": true,
        "clear": false
      }
    }
  ]
}