Datagram Socket Listener Windows Store App

Introduction

In this article I describe how to create Windows Store App for Datagram Socket Listener using JavaScript. A Datagram Socket is used to create the "server" side of a connection. It listens on a "service name" (often a port number) and each time a datagram is received on the port number it fires a MessageReceived event.

I assume you can create a simple Windows Store App using JavaScript; for more help visit Simple Windows Store Apps using JavaScript.

To start the creation of the apps, add two JavaScript pages by right-clicking on the js folder in the Solution Explorer and select "Add" > "New item" > "JavaScript Page" and then provide an appropriate name. In the same way, add a HTML page to your project.

Write the following code in the default.html

<!DOCTYPE html>

<html>

<head>

    <meta charset="utf-8" />

    <title></title>

    <link rel="stylesheet" href="//Microsoft.WinJS.1.0/css/ui-light.css" />

    <script src="//Microsoft.WinJS.1.0/js/base.js"></script>

    <script src="//Microsoft.WinJS.1.0/js/ui.js"></script>

    <link rel="stylesheet" href="/css/default.css" />

    <script src="/js/default.js"></script>

</head>

<body role="application" style="background-color: lightgoldenrodyellow">

    <center><div id="rootGrid">

        <div id="content">

            <h1 id="featureLabel"></h1>

            <div id="contentHost"></div>

        </div>

    </div>

        </center>

</body>

</html>

Write the following code in the default.js:
 

(function () {

    "use strict";

    var appTitle = "DatagramSocket";

    var pagess = [

        { url: "page.html", title: "Close Socket" }

    ];

    function activated(eventObject) {

        if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {

            eventObject.setPromise(WinJS.UI.processAll().then(function () {

                var url = WinJS.Application.sessionState.lastUrl || pages[0].url;

                return WinJS.Navigation.navigate(url);

            }));

        }

    }

    WinJS.Navigation.addEventListener("navigated", function (eventObject) {

        var url = eventObject.detail.location;

        var host = document.getElementById("contentHost");

        host.winControl && host.winControl.unload && host.winControl.unload();

        WinJS.Utilities.empty(host);

        eventObject.detail.setPromise(WinJS.UI.Pages.render(url, host, eventObject.detail.state).then(function () {

            WinJS.Application.sessionState.lastUrl = url;

        }));

    });

    WinJS.Namespace.define("App", {

        appTitle: appTitle,

        pages: pages

    });

    WinJS.Application.addEventListener("activated", activated, false);

    WinJS.Application.start();

})(); 


Write the following code in the page.html:
 

<!DOCTYPE html>

<html>

<head>

    <script src="/js/script1.js"></script>

    <script src="/js/script.js"></script>

</head>

<body>

    <div data-win-control="App.pageInput">

        <p>

            <label for="serviceNameAccept">Service Name:</label>

            <input id="serviceNameAccept" type="text" />

        </p>

        <p>

            <button id="buttonStartListener">Listen</button>

        </p>

    </div>

    <div data-win-control="App.pageOutput">

        <p id="statusBox"></p>

        <p id="outputBox"></p>

    </div>

</body>

</html>

Write the following code in the script.js:
 

(function () {

    "use strict";

    var page = WinJS.UI.Pages.define("page.html", {

        ready: function (element, options) {

            document.getElementById("buttonStartListener").addEventListener("click", startListener, false);

            document.getElementById("serviceNameAccept").addEventListener("change", socketsapp.getValues, false);

            socketsapp.setValues();

        }

    });

    function startListener() {

        var serviceName = document.getElementById("serviceNameAccept").value;

        if (serviceName === "") {

            socketsapp.displayStatus("Please provide a service name.");

            return;

        }

 

        if (socketsapp.listener) {

            socketsapp.displayStatus("Already have a listener; call close to close the listener.");

            return;

        }

        socketsapp.closing = false;

        socketsapp.bindingToService = true;

        socketsapp.listener = new Windows.Networking.Sockets.DatagramSocket();

        socketsapp.listener.addEventListener("messagereceived", onServerMessageReceived);

        socketsapp.displayStatus("Server: listener creation started.");

        socketsapp.listener.bindServiceNameAsync(serviceName).done(function () {

            socketsapp.displayStatus("Server: listener creation completed.");

            socketsapp.bindingToService = false;

        }, onError);

    }

    function onServerMessageReceived(eventArgument) {

        if (socketsapp.listenerOutputStream) {

            echoMessage(socketsapp.listenerOutputStream, eventArgument);

            return;

        }

        socketsapp.listener.getOutputStreamAsync(eventArgument.remoteAddress, eventArgument.remotePort).done(function (outputStream) {

            if (!socketsapp.listenerOutputStream) {

                socketsapp.listenerOutputStream = outputStream;

                socketsapp.listenerPeerAddress = eventArgument.remoteAddress;

                socketsapp.listenerPeerPort = eventArgument.remotePort;

            }

            echoMessage(socketsapp.listenerOutputStream, eventArgument);

        });

    }

    function echoMessage(outputStream, eventArgument) {

        if (socketsapp.listenerPeerAddress !== eventArgument.remoteAddress ||

            socketsapp.listenerPeerPort !== eventArgument.remotePort) {

            socketsapp.displayStatus("Got datagram from " + eventArguments.remoteAddress + ":" + eventArguments.remotePort +

                ", but already 'connected' to " + socketsapp.listenerPeerAddress + ":" + socketsapp.listenerPeerPort);

            return;

        }

        outputStream.writeAsync(eventArgument.getDataReader().detachBuffer()).done(function () {

        });

    }

    function onError(reason) {

        if (socketsapp.bindingToService) {

            socketsapp.listener = null;

            socketsapp.bindingToService = false;

        }

        if (!socketsapp.closing) {

            socketsapp.displayStatus(reason);

        }

    }

})();


Write the following code in the script1.html:
 

var socketsapp = {};

(function () {

    "use strict";

    socketsapp.listener = null;

    socketsapp.listenerOutputStream = null;

    socketsapp.listenerPeerAddress = null;

    socketsapp.listenerPeerPort = null;

    socketsapp.clientSocket = null;

    socketsapp.clientDataWriter = null;

    socketsapp.connected = false;

    socketsapp.closing = false;

    socketsapp.bindingToService = false;

    socketsapp.serviceNameAccept = "22112";

    socketsapp.hostNameConnect = "localhost";

    socketsapp.serviceNameConnect = "22112";

    socketsapp.close = function () {

        socketsapp.closing = true;

        if (socketsapp.listener) {

            socketsapp.listener.close();

        }

        if (socketsapp.clientSocket) {

            socketsapp.clientSocket.close();

        }

        if (socketsapp.clientDataWriter) {

            socketsapp.clientDataWriter.close();

        }

        if (socketsapp.listenerOutputStream) {

            socketsapp.listenerOutputStream.close();

        }

        socketsapp.listener = null;

        socketsapp.listenerOutputStream = null;

        socketsapp.listenerPeerAddress = null;

        socketsapp.listenerPeerPort = null;

        socketsapp.clientSocket = null;

        socketsapp.clientDataWriter = null;

        socketsapp.connected = false;

    };

    socketsapp.displayStatus = function (message) {

        document.getElementById("statusBox").innerHTML = message;

    };

    socketsapp.displayOutput = function (message) {

        document.getElementById("outputBox").innerHTML = message;

    };

    socketsapp.setValues = function () {

        var serviceNameAcceptInput = document.getElementById("serviceNameAccept");

        var hostNameConnectInput = document.getElementById("hostNameConnect");

        var serviceNameConnectInput = document.getElementById("serviceNameConnect");

 

        if (serviceNameAcceptInput) {

            serviceNameAcceptInput.value = socketsapp.serviceNameAccept;

        }

        if (hostNameConnectInput) {

            hostNameConnectInput.value = socketsapp.hostNameConnect;

        }

        if (serviceNameConnectInput) {

            serviceNameConnectInput.value = socketsapp.serviceNameConnect;

        }

    };

    socketsapp.getValues = function (evt) {

        switch (evt.target.id) {

            case "serviceNameAccept":

                socketsapp.serviceNameAccept = evt.target.value;

                break;

            case "hostNameConnect":

                socketsapp.hostNameConnect = evt.target.value;

                break;

            case "serviceNameConnect":

                socketsapp.serviceNameConnect = evt.target.value;

                break;

        }

    };

})();


Output:

socket-listner-windows-store-app.jpg

Summary


In this article I described how to create a Windows Store App for Datagram Socket Listener using JavaScript. I hope this article has helped you to understand this topic. Please share it. If you know more about this, your feedback and constructive contributions are welcome.