Windows 8 Store Apps Learning (68) Background tasks: Control channel (Controlchannel)

Introduced

Re-imagine Windows 8 Store Apps after a task

Control channel (Controlchannel)

Example

1, client and server to do Controlchannel communication key code

Controlchannelhelper/appcontext.cs

 * * This example uses global static variables to share information about the app and task so that background tasks can get information about the app. * 
 Note:
 * can also be achieved through Windows.ApplicationModel.Core.CoreApplication.Properties save data to implement the information sharing of app and task
 * *
    
using System.Collections.Concurrent;
Using Windows.Networking.Sockets;
    
Namespace Controlchannelhelper
{public
    class Appcontext
    {
        ///<summary>
        ///from Controlchannel received data
        ///</summary> public
        static concurrentqueue<string> MessageQueue = new Concurrentqueue<string> ();
    
        <summary>
        ///Client socket
        ///</summary> public
        static Streamsocket clientsocket;
    }
}

Controlchannelhelper/socketcontrolchannel.cs

* * Implement a Socket TCP communication controlchannel,client will receive data in real time in this controlchannel * NOTE: * WIN8 client and Socket server cannot be deployed in On the same machine, otherwise throws an exception: {The referenced object type does not support the attempted operation.
 (Exception from hresult:0x8007273d)}
* * using System;
Using System.Threading.Tasks;
Using Windows.ApplicationModel.Background;
Using Windows.foundation;
Using Windows.networking;
Using Windows.Networking.Sockets;
    
Using Windows.Storage.Streams;
        Namespace Controlchannelhelper {public class Socketcontrolchannel:idisposable {//Controlchannel
    
        Public Controlchanneltrigger Channel {get; set;}
        Client socket private Streamsocket _socket;
        Used to send data private datawriter _datawriter;
    
        Used to receive data private DataReader _datareader;
        Send heartbeat intervals to the server in minutes, min 15 minutes private uint _serverkeepaliveinterval = 15;
    
        Controlchannel Identity private String _channelid = "Mycontrolchannel";
    
  Public Socketcontrolchannel () {      Public async task<string> CreateChannel () {Dispose (); try {//instantiate a controlchannel Channel = new Controlchanneltrigger (_channelid,
            _serverkeepaliveinterval, Controlchanneltriggerresourcetype.requesthardwareslot);
                catch (Exception ex) {Dispose (); Return ' Control channel creation failed: ' + ex.
            ToString (); //Register the background task used to send heartbeat to the server socket, need to do related configuration in manifest var keepalivebuilder = new BACKGROUNDTASKB
            Uilder ();
            Keepalivebuilder.name = "Mycontrolchannelkeepalive"; Note: If the WebSocket protocol is gone, the system has built-in logic for sending a heartbeat, which is specified here directly as Windows.Networking.Sockets.WebSocketKeepAlive Keepalivebu Ilder.
            Taskentrypoint = "Backgroundtasklib.controlchannelkeepalive"; Keepalivebuilder.settrigger (Channel.keepalivetrigger); triggered when the heartbeat interval is sent, this example is 15 minutes KEEPALIVEBUILDER.REgister (); Register for the background task to display notifications to users, need to do related configuration in manifest//view more highlights in this column: Http://www.bianceng.cnhttp://www.bianceng.cn/Programming/net
            /var pushnotifybuilder = new Backgroundtaskbuilder ();
            Pushnotifybuilder.name = "Mycontrolchannelpushnotification";
            Pushnotifybuilder.taskentrypoint = "Backgroundtasklib.controlchannelpushnotification"; Pushnotifybuilder.settrigger (Channel.pushnotificationtrigger);
    
            The Pushnotifybuilder.register () is triggered when the pushed data is received in the Controlchannel;
                try {_socket = new streamsocket ();
    
                Appcontext.clientsocket = _socket;
    
                In Controlchannel, the Streamsocket communication Channel.usingtransport (_socket) is specified; The client socket connects to the server socket await _socket.
    
                ConnectAsync (New HostName ("192.168.6.204"), "3366"); Start waiting for data pushed over Controlchannel, if WIN8 client and socket SERVer is deployed on the same machine, the exception is thrown here controlchanneltriggerstatus status = channel.waitforpushenabled (); if (status!= controlchanneltriggerstatus.hardwareslotallocated && status!= controlchanneltriggerstatus.so ftwareslotallocated) return "Control channel creation failed:" + status.
    
                ToString (); Send data to server _datawriter = new DataWriter (_socket.
                OutputStream);
                String message = "Hello" + DateTime.Now.ToString ("hh:mm:ss") + "^";
                _datawriter.writestring (message);
    
                await _datawriter.storeasync ();
            Receive data Receivedata ();
                catch (Exception ex) {Dispose (); Return ' Control channel creation failed: ' + ex.
            ToString ();
        return "OK";
    
            //start receiving this data private void Receivedata () {UINT MAXBUFFERLENGTH = 256;
       Try     {var buffer = new Windows.Storage.Streams.Buffer (maxbufferlength); var asyncoperation = _socket.
                Inputstream.readasync (buffer, maxbufferlength, inputstreamoptions.partial); asyncoperation.completed = (Iasyncoperationwithprogress<ibuffer, uint> asyncinfo, AsyncStatus AsyncStatus) = > {switch (asyncstatus) {case ASYNCST ATUs.
                                Completed:case AsyncStatus.Error:try {
                                Ibuffer bufferread = Asyncinfo.getresults ();
                                UINT bytesread = bufferread.length;
    
                                _datareader = Datareader.frombuffer (Bufferread);
                            The data received the completion of receivecompleted (Bytesread); catch (Exception Ex) {AppContext.MessageQueue.Enqueue (ex.
                            ToString ());
                        } break;
                            Case AsyncStatus.Canceled:AppContext.MessageQueue.Enqueue ("canceled when receiving data");
                    Break
            }
                }; The catch (Exception ex) {AppContext.MessageQueue.Enqueue (ex).
            ToString ());  } public void receivecompleted (UINT bytesread) {//Get the data received this time uint
            Bufferlength = _datareader.unconsumedbufferlength;
    
            String message = _datareader.readstring (bufferlength);
    
            The received data is put into memory, which is handled by Pushnotificationtrigger triggered by the background (and can also be processed here) AppContext.MessageQueue.Enqueue (message);
        Start receiving next data receivedata (); }//Free resources public void Dispose () {lock (this) {if (_datawriter!= null) {
                        try {_datawriter.detachstream ();
                    _datawriter = null;
    
                \ catch (Exception ex) {}}
                        if (_datareader!= null) {try {
                        _datareader.detachstream ();
                    _datareader = null;
    
                catch (Exception exp) {}} if (_socket!= null) {_socket.
                    Dispose ();
                _socket = null;
                    } if (Channel!= null) {channel.dispose (); CHannel = null; }
            }
        }
    }
}

2. Service End

Backgroundtasklib/controlchannelkeepalive.cs