I am developing a Windows Phone 8.1 chat app and discovered multiple difficulties during programming a socket interoperability.
The main issue are 'events' on a socket, and main question is: How to subscribe to OnData event, e.g. how to detect the event, when data came from the server?
I tried to solve it by direct way: infinite reading from InputStream, and that works with 50/50 luck: sometimes that method freeze the UI stream (even the reading method is async).
I googled for that issue, because it's a very strange behavior for that important component, and didn't found any solutions for this even on MSDN. At SO I found only same solutions like mine, but they also freeze UI flow.
For reference, my app infrastructure is the main app that uses facade class from shared library, the facade class get a generic, that specify concrete behavior (this was done for reason of multiple data transports). For TCP transport, I wrote that:
public class TCPTransport : ITransportProvider
{
private bool _connected { get; set; }
private StreamSocket _socket { get; set; }
private DataReader _input { get; set; }
public TCPTransport()
{
_socket = new StreamSocket();
}
public async Task<bool> Connect(string host, int port)
{
try
{
await _socket.ConnectAsync(new HostName(host), port.ToString());
if (OnConnect != null)
OnConnect();
_connected = true;
_input = new DataReader(_socket.InputStream)
{
InputStreamOptions = InputStreamOptions.Partial
};
_read();
return _connected;
}
catch(Exception e)
{
Debug.WriteLine("[warn] cant conect to " + host + ":" + port + ". Additional: " + e.Message);
return false;
}
}
async private void _read()
{
while (true)
{
if (!_connected || _socket == null) break;
uint buffer = await _input.LoadAsync(2048);
string data = _input.ReadString(buffer);
if (OnData != null && data.Length != 0)
OnData(data);
}
}
public async Task<bool> Send(string data)
{
if (!_connected) return false;
try
{
await _socket.OutputStream.WriteAsync(Encoding.UTF8.GetBytes(data).AsBuffer());
}
catch (Exception e)
{
System.Diagnostics.Debug.WriteLine("[warn] Exception send: " + e.Message);
}
return true;
}
public bool Close()
{
if (!_connected) return false;
_socket.Dispose();
return true;
}
public Action OnConnect { get; set; }
public Action<string> OnData { get; set; }
public Action OnClose { get; set; }
}
I suppose that I am wrong about using that solution, but how can I listen to data from server?
For better or worse, the StreamSocket API is not designed as an event-driven API; it is designed as an asynchronous API. If you want to raise an event when data is available, use an event, not a delegate:
Here is a trivial example (hard-coded to www.microsoft.com and with no error handling) showing how to simulate the event:
Note that if you run with the debugger attached, it will temporarily freeze the UI thread. This doesn't occur when not debugging
// Create your own class to hold the data
public class DataReceivedEventArgs : EventArgs
{
public uint DataCount { get; private set; }
public DataReceivedEventArgs(uint dataCount)
{
DataCount = dataCount;
}
}
// Now inside your MainPage...
bool m_keepReading = false;
bool m_eventHandled = false;
public event TypedEventHandler<MainPage, DataReceivedEventArgs> DataReceived;
// Hook this up to (eg) a Button
private async void StartSockets(object sender, RoutedEventArgs e)
{
if (!m_eventHandled)
DataReceived += (s, args) => Debug.WriteLine(args.DataCount);
m_eventHandled = true;
m_keepReading = true;
DoSocketTestAsync();
}
// Hook this up to (eg) a Button
private void StopSockets(object sender, RoutedEventArgs e)
{
m_keepReading = false;
}
private async Task DoSocketTestAsync()
{
var socket = new StreamSocket();
await socket.ConnectAsync(new HostName("www.microsoft.com"), "http");
var writer = new DataWriter(socket.OutputStream);
writer.WriteString("GET /en-us HTTP/1.1\r\nHOST: www.microsoft.com\r\n\r\n");
await writer.StoreAsync();
ReadSocketAsync(socket);
}
private async void ReadSocketAsync(StreamSocket socket)
{
while (m_keepReading)
{
const uint size = 2048;
IBuffer buffer = new Windows.Storage.Streams.Buffer(size);
buffer = await socket.InputStream.ReadAsync(buffer, size,
InputStreamOptions.Partial);
var handler = DataReceived;
if (handler != null && buffer.Length > 0)
handler(this, new DataReceivedEventArgs(buffer.Length));
}
}
Now when you click the "start" button, assuming you have a network connection you will see some numbers start appearing in the Debug Output window.
(Also note that using private auto-implemented properties doesn't really buy you anything; just make them fields).
Related
I have a WPF (.NET Framework 4.6) application that uses websocket-sharp (version 3.0.0) to create a websocket server.
I have a WebsocketServer and using EventHandler to tranfer event to MainWindow.xaml.cs but it not working. The MainWindow.xaml.cs listened to a RaiseOnScanDevice event but not any event invoked here.
I think this issue is relative to different thread. I try using Dispatcher.Invoke but it still not working.
System.Windows.Application.Current.Dispatcher.Invoke(new System.Action(() =>
{
RaiseOnScanDevice(this, new EventArgs());
}));
I found an issue (https://github.com/sta/websocket-sharp/issues/350) but the answers do not resolve my issue.
Please help me a solution for this issue.
WebsocketServer.cs file
public class WebsocketServer : WebSocketBehavior
{
private static readonly Lazy<WebsocketServer> lazyInstance = new Lazy<WebsocketServer>(() => new WebsocketServer());
public static WebsocketServer Instance
{
get
{
return lazyInstance.Value;
}
}
private const string TAG = "WebsocketServer";
private const string HOST_IP_ADDRESS = "127.0.0.2"; // localhost
private const int PORT = 38001;
public WebSocketServer socket;
private PacketHandler packetHandler = new PacketHandler();
public event EventHandler<EventArgs> RaiseOnScanDevice = new EventHandler<EventArgs>((a, e) => { });
public WebsocketServer()
{
Initialize();
}
public void Initialize()
{
socket = new WebSocketServer(IPAddress.Parse(HOST_IP_ADDRESS), PORT);
socket.AddWebSocketService<WebsocketServer>("/");
StartServer();
}
public void StartServer()
{
socket.Start();
}
public void StopServer()
{
socket.Stop();
}
protected override Task OnOpen()
{
return base.OnOpen();
}
protected override Task OnClose(CloseEventArgs e)
{
return base.OnClose(e);
}
protected override Task OnError(ErrorEventArgs e)
{
return base.OnError(e);
}
protected override Task OnMessage(MessageEventArgs e)
{
System.IO.StreamReader reader = new System.IO.StreamReader(e.Data);
string message = reader.ReadToEnd();
//Converting the event back to 'eventName' and 'JsonPayload'
PacketModel packet = packetHandler.OpenPacket(message);
HandleMessageFromClient(packet);
return base.OnMessage(e);
}
private void HandleMessageFromClient(PacketModel packet) {
var eventName = packet.EventName;
var data = packet.Data;
if (eventName == null || eventName.Equals(""))
{
return;
}
switch (eventName)
{
case SocketEvent.Hello:
Send("OK");
break;
case SocketEvent.ScanDevice:
ScanDevice();
break;
default:
break;
}
}
private void ScanDevice()
{
try
{
RaiseOnScanDevice(this, new EventArgs());
// or dispatch to Main Thread
System.Windows.Application.Current.Dispatcher.Invoke(new System.Action(() =>
{
RaiseOnScanDevice(this, new EventArgs());
}));
}
catch (Exception exception)
{
Console.WriteLine(exception);
}
}
}
MainWindow.xaml.cs file
public partial class MainWindow : Window
{
public WebsocketServer WebsocketConnection
{
get { return WebsocketServer.Instance; }
}
public MainWindow()
{
InitializeComponent();
WebsocketConnection.RaiseOnScanDevice += SocketConnection_RaiseOnScanDevice;
}
private void SocketConnection_RaiseOnScanDevice(object sender, EventArgs e)
{
Console.WriteLine("SocketConnection_RaiseOnScanDevice");
}
The queue of messages is a good idea but you may want to use a lock to guard access to it. Most likely it won't be an issue but if you don't, you leave yourself open to the possibility of an error if the coroutine is reading from the queue as the websocket is writing to it. For example you could do something like this:
var queueLock = new object();
var queue = new Queue<MyMessageType>();
// use this to read from the queue
MyMessageType GetNextMessage()
{
lock (queueLock) {
if (queue.Count > 0) return queue.Dequeue();
else return null;
}
}
// use this to write to the queue
void QueueMessage(MyMessageType msg)
{
lock(queueLock) {
queue.Enqueue(msg);
}
}
I have been given the task to create a interface where I receive data through socket from the sender, for this purpose I am using NetMQ PushSocket for the sender side and then I receive the data at client side sung PullSocket and I have to update the UI (WPF app) when data is received so I receive data using poller in ReceiveReady event of the PullSocket when I do this in a seperate service class and call that class in UI ViewModel the UI thread hangs, so I use Poller.Run in a task, now the problem is that when I stop the poller and then restart it again it doesn't call the ReceiveReady event
Here is the ReceiverService for receiving the data.
public class ReceiverService
{
string msg;
string _address;
int _port;
PullSocket receiver;
NetMQPoller poller;
private MapViewModel ViewModel { get; set; }
public ReceiverService(MapViewModel mapViewModel, int port = 5555)
{
_address = GetComputerLanIP();
_port = port;
receiver = new PullSocket($"tcp://{_address}:{_port}");
receiver.Options.Linger = TimeSpan.Zero;
this.ViewModel = mapViewModel;
poller = new NetMQPoller { receiver };
receiver.ReceiveReady += receiver_ReceiveReady;
}
public void Start()
{
receiver.Connect($"tcp://{_address}:{_port}");
poller.Run();
}
public void Stop()
{
receiver.Disconnect($"tcp://{_address}:{_port}");
poller.Stop();
}
private void receiver_ReceiveReady(object sender, NetMQSocketEventArgs e)
{
// receive won't block as a message is ready
msg = e.Socket.ReceiveFrameString();
// send a response
if (!string.IsNullOrEmpty(msg))
{
try
{
//Updaing the ViewModel here
}
catch (Exception ex)
{
System.Diagnostics.Debug.WriteLine(ex.Message);
}
}
}
private string GetComputerLanIP()
{
string strHostName = Dns.GetHostName();
IPHostEntry ipEntry = Dns.GetHostEntry(strHostName);
foreach (var ipAddress in ipEntry.AddressList)
{
if (ipAddress.AddressFamily == AddressFamily.InterNetwork)
{
return ipAddress.ToString();
}
}
return "";
}
private string GetValueFromMessage(string identifier)
{
msg.Replace("{", "");
msg.Replace("}", "");
identifier = /*" " + */identifier + " = ";
try
{
int index = msg.IndexOf(identifier) + identifier.Length;
if (index != -1)
{
int index2 = msg.IndexOf(";", index);
if (index2 == -1)
{
index2 = msg.Length;
}
return msg.Substring(index, index2 - index);
}
}
catch (IndexOutOfRangeException ex)
{
return null;
}
return null;
}
}
and in my ViewModel I have set commands for these
private void StartReceiver()
{
Task.Run(() => ReceiverService.Start());
}
private void StopReceiver()
{
Task.Run(() => ReceiverService.Stop());
}
What am I doing wrong? I am new to NetMQ and WPF. TIA
at first it would be good to make a task inside ReceiverService, kind of an ActorModel, because in the end if You would like to reuse it anywhere You need to remember that You should creat a Task first.
always it would be good to have socket in using statement, because You should always close socket if You are not using it
public async Task StartAsync() {
await Task.Run(() => ThreadBody())
}
public void Stop()
{
_poller.Stop();
}
private void ThreadBody()
{
using (PullSocket receiverSocket = new PullSocket())
using (_poller = new NetMQPoller())
{
receiverSocket.Connect($"tcp://{_address}:{_port}");
receiverSocket.ReceiveReady += receiver_ReceiveReady;
_poller.Add(receiverSocket);
_poller.Run();
}
}
I know, the title might be confusing, but I can't really express it better in short.
Basically, I'm writing a TCP Server. I don't have a Windows Form to show, the only thing the user sees is a TrayIcon.
My TCP Server class creates a thread for listening for clients, and then additional thread for every client handling communication. When all communication is done, I want to call a method on the main thread.
I've done it by firing a event from the client communication thread which gets handled on the main thread, and all worked fine until I wanted to add desktop notifications to my application. I've build a notification using WPF (iControlNotification) and wanted to show it in the event handler I mentioned before, but I'm getting a error message saying something like "The calling thread has to be a STA Thread".
Here's some code (I removed unnecessary party):
static class Program {
[...]
[STAThread]
static void Main() {
Log("iControlServerApplication started.");
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
trayIcon = new TrayIcon();
trayIcon.Display();
NotificationManager = new iControlNotificationManager();
server = new TCPServer();
server.CommandReceived += new TCPServer.CommandReceivedEventHandler(tcpServer_CommandReceived);
if (server.Start()) {
NotificationManager.ShowNotfication("iControl Server Application", "Server started. " + plugins.Count + " plugins loaded.");
Application.Run();
} else {
MessageBox.Show("Port " + server.Port + " is already in use. Server could not be started.", ApplicationName, MessageBoxButtons.OK, MessageBoxIcon.Error);
}
}
[...]
static void tcpServer_CommandReceived(object source, TCPServer.CommandReceivedEventArgs e) {
string toolTipText = "[" + e.Client.IPAddress + "] >> " + e.Command;
NotificationManager.ShowNotfication("iControl Server Application", toolTipText);
foreach (IiControlPlugin plugin in plugins) {
plugin.Handle(e.SplittedCommands, e.Client);
}
}
[...]
}
-
class TCPServer {
public delegate void CommandReceivedEventHandler(object source, CommandReceivedEventArgs e);
public event CommandReceivedEventHandler CommandReceived;
public class CommandReceivedEventArgs : EventArgs {
private string _command;
private string[] _splittedCommands;
private iControlClient _client;
public CommandReceivedEventArgs(string command, iControlClient client) {
_command = command;
_splittedCommands = command.Split(new Char[]{' '});
_client = client;
}
public string Command { get { return _command; } }
public string[] SplittedCommands { get { return _splittedCommands; } }
public iControlClient Client { get { return _client; } }
}
public TCPServer() {
this.tcpListener = new TcpListener(IPAddress.Any, Port);
this.icClients = new Dictionary<String, iControlClient>();
}
public Boolean Start() {
if (PortIsAvailable(Port)) {
this.listenThread = new Thread(new ThreadStart(ListenForClients));
this.listenThread.Start();
Program.Log("ListeningThread started.");
return true;
} else {
return false;
}
}
private void ListenForClients() {
this.tcpListener.Start();
TcpClient client;
while (this.keepListening) {
try {
client = this.tcpListener.AcceptTcpClient();
} catch {
break;
}
iControlClient icClient = new iControlClient(client);
icClient.Thread = new Thread(new ParameterizedThreadStart(HandleClientCommunication));
icClient.Thread.Start(icClient);
}
Program.Log("Stop listening.");
}
private void HandleClientCommunication(object client) {
iControlClient icClient = (iControlClient)client;
NetworkStream clientStream = icClient.TCP.GetStream();
clientStream.ReadTimeout = 10;
int bufflen = 4096;
byte[] message = new byte[bufflen];
int bytesRead;
while (this.keepReceiving && icClient.keepConnected) {
bytesRead = 0;
try {
bytesRead = clientStream.Read(message, 0, bufflen);
} catch {
break;
}
if (bytesRead == 0) {
break;
}
ProcessReceivedData(icClient, ParseData(message, bytesRead));
}
Program.Log("[" + icClient.IPAddress + "] Connection closed.");
icClient.TCP.Close();
this.icClients.Remove(icClient.IPAddress);
}
private void ProcessReceivedData(iControlClient icClient, String[] commands) {
Program.Log("[" + icClient.IPAddress + "] >> " + String.Join(" ", commands));
if (this.CommandReceived != null) {
CommandReceived(this, new CommandReceivedEventArgs(String.Join(" ", commands), icClient));
}
NetworkStream clientStream = icClient.TCP.GetStream();
ASCIIEncoding encoder = new ASCIIEncoding();
byte[] buffer = encoder.GetBytes("::ok");
clientStream.Write(buffer, 0, buffer.Length);
clientStream.Flush();
icClient.keepConnected = false;
}
}
-
public class iControlNotificationManager {
private iControlNotifications _notifications;
public void ShowNotfication(string caption, string message) {
if ((Boolean)Program.GetSetting("notifications", true) == false) return;
Dispatcher.CurrentDispatcher.Invoke(System.Windows.Threading.DispatcherPriority.Normal, new Action(
() => {
iControlNotification noti = new iControlNotification(caption, message);
noti.Show();
}));
}
}
-
public class iControlNotification : Window {
private iControlNotificationModel _notification;
public iControlNotification(string caption, string message) { // Here's the error
InitializeComponent();
_notification = new iControlNotificationModel() {
Caption = caption,
Message = message
};
this.DataContext = _notification;
}
}
So how should I call tcpServer_CommandReceived so that the Notification Window can be shown the right way?
I'm really stuck here, I really appreciate any help on this!
//How to call a method from another thread :
a) You can invoke it in other thread by passing SynchronizationContext object to it:
void Method(object s)
{
SynchronizationContext sync = s as SynchronizationContext;
sync.Post(delegate { // what to do in other thread}, null);
}
Then in code you run this method in new task, passing your sync context as object (for example):
Task t = Task.Factory.StartNew(Method, SynchronizationContext.Current);
b) You can create extension method for this purpose (here is example that i used in win forms application to update UI):
public static class ControlExtensions
{
/// Executes the Action asynchronously on the UI thread, does not block execution on the calling thread.
public static void UIThread(this Control #this, Action code)
{
if (#this.InvokeRequired)
{
#this.BeginInvoke(code);
}
else
{
code.Invoke();
}
}
}
this is basically a follow up to a previous question (Triggering an event in c# from c++ and declaring LPCWSTR). I've revised my code based on the answers and comments I have received and I solved the initial issue, which was passing the event to the GpioSetupInterruptPin from a gpio api. I don't have a lot of documentation on the api but what i'm trying to achieve is: have a form with a white label; after pressing a switch, the label turns yellow.
The problem i'm having now is the event seems to trigger as soon as it's created (the "execute" message is passed to the debug dialog and the label turns yellow) but it doesn't do anything when i toggle the switch. I was told in the last question to use WaitForSingleObject but i'm not really sure where to call it and this article only added to my confusion.
public partial class Form1 : Form
{
// P/Invoke CreateEvent and WaitForSingleObject
private void GPIO_Open() //get handle for gpio
private void GPIO_Output() //output pin declaration
private void button1_Click(object sender, EventArgs e)
{
Interrupt_Setup();
}
private void Interrupt_Setup()
{
hGPIO = GPIOapi.GpioOpenHandle(); //returns a handle to the gpio
GIPO_ON = true;
Debug.WriteLine("Driver open \n" + hGPIO);
GPIO_Output(); //set output pins
GPIO_Interrupt(Trigger); //configure interrupt
}
private void GPIO_Interrupt(string trigger)
{
bool ok;
_Main();
//INTERRUPT DECALRATION
ok = GPIOapi.GpioSetupInterruptPin(hGPIO, port6, 4, GPIOapi.INT_TRIGGER_MODE.TRIGGER_MODE_EDGE,
GPIOapi.INT_TRIGGER_POLARITY.TRIGGER_POL_HIGH_RISING, trigger, true);
Thread waitThread=new Thread(WaitForTrigger);
waitThread.Start();
if (!ok)
Debug.WriteLine("NO interrupt");
else
Debug.WriteLine("Interrupt set for:" + port6 + "04" + " at " + hGPIO);
}
public static string Trigger = "InputProcessUpdateHandler";
public static IntPtr handle = CreateEvent(IntPtr.Zero, false, false, Trigger); //used P/Invoke
private static InputProcessor inputProcessor = null;
public Color[] color =
{
Color.Orchid, Color.DarkOrchid, Color.GreenYellow, Color.CornflowerBlue, Color.SteelBlue,Color.Crimson
};
public int i = 0;
public void WaitForTrigger()
{
while(true)
{try
{
if (WaitForSingleObject(handle, 0xFFFFFFFF) == false)
{
BeginInvoke(((System.Action)(() =>label2.BackColor = color[i])));
i++;
if (i > 4)
i = 0;
}
Thread.Sleep(300);
}
catch (Exception e)
{ Debug.WriteLine("exception: " + e); }}
}
}
private void _Main()
{
inputProcessor = new InputProcessor();
ShowToggle showToggle = new ShowToggle(inputProcessor);
inputProcessor.Process(label1);
}
public class ShowToggle
{
private InputProcessor _inputProcessor = null;
public ShowToggle(InputProcessor inputProcessor)
{
_inputProcessor = inputProcessor;
_inputProcessor.updateHandledBy += InputProcessUpdateHandler;
}
private void InputProcessUpdateHandler(Label label)
{
label.BackColor = Color.Yellow;
Debug.Write("execute");
}
}
public class InputProcessor
{
public delegate void InputProcessUpdateHandler(Label label);
public event InputProcessUpdateHandler updateHandledBy = null;
public void Process(Label label)
{
if (updateHandledBy != null)
updateHandledBy(label);
}
}
If anyone could help me with this, I would be very grateful.
*** I got it working but it looks a right mess. Could anyone help me straighten it out?
You code is really confusing to me. I think what you want is something like this. Bear in mind I'm typing this into the SO text editor, so don't expect it to compile and just work - it's a guide. Consider it a step above pseudocode.
public class DeviceInterrupt
{
IntPtr m_gpio;
string m_eventName;
public event EventHandler OnInterrupt;
public DeviceInterrupt(int port)
{
// get a driver handle
m_gpio = GPIO_Open();
// generate some unique event name
m_eventName = "GPIO_evt_" + port;
// wire up the interrupt
GpioSetupInterruptPin(m_gpio, port, m_eventName, ...);
// start a listener
new Thread(EventListenerProc)
{
IsBackground = true,
Name = "gpio listener"
}
.Start();
}
public void Dispose()
{
// TODO: release the handle
}
private void EventListenerProc()
{
// create the event with the name we sent to the driver
var wh = new WaitHandle(false, m_eventName);
while (true)
{
// wait for it to get set by the driver
if (wh.WaitOne(1000))
{
// we have an interrupt
OnInterrupt.Fire(this, EventArgs.Empty);
}
}
}
}
Usage would then be something like this:
var intr = new DeviceInterrupt(4);
intr.OnInterrupt += MyHandler;
....
void MyHandler(object sender, EventArgs a)
{
Debug.WriteLine("Interrupt occurred!");
}
Note
The Compact Framework doesn't support actual named system events, so the named WaitHandle I use in my code above is not a CF-supplied WaitHandle. Instead I'm using the one from the Smart Device Framework. You could also P/Invoke to CreateEvent and WaitForSingleObject yourself.
So, first I have read a ton of threads on this particular problem and I still do not understand how to fix it. Basically, I am trying to communicate with a websocket and store the message received in an observable collection that is bound to a listview. I know that I am getting a response back properly from the socket, but when it tries to add it to the observable collection it gives me the following error:
The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))
I've read some information on "dispatch" as well as some other things, but I am just massively confused! Here is my code:
public ObservableCollection<string> messageList { get; set; }
private void MessageReceived(MessageWebSocket sender, MessageWebSocketMessageReceivedEventArgs args)
{
string read = "";
try
{
using (DataReader reader = args.GetDataReader())
{
reader.UnicodeEncoding = Windows.Storage.Streams.UnicodeEncoding.Utf8;
read = reader.ReadString(reader.UnconsumedBufferLength);
}
}
catch (Exception ex) // For debugging
{
WebErrorStatus status = WebSocketError.GetStatus(ex.GetBaseException().HResult);
// Add your specific error-handling code here.
}
if (read != "")
messageList.Add(read); // this is where I get the error
}
And this is the binding:
protected override async void OnNavigatedTo(NavigationEventArgs e)
{
//await Authenticate();
Gameboard.DataContext = Game.GameDetails.Singleton;
lstHighScores.ItemsSource = sendInfo.messageList;
}
How do I make the error go away while still binding to the observable collection for my listview?
This solved my issue:
Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
);
Correct way to get the CoreDispatcher in a Windows Store app
Try replacing
messageList.Add(read);
with
Dispatcher.Invoke((Action)(() => messageList.Add(read)));
If you're calling from outside your Window class, try:
Application.Current.Dispatcher.Invoke((Action)(() => messageList.Add(read)));
Slight modification for task based async methods but the code in here will not be awaited.
await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
).AsTask();
This code WILL await, and will allow you to return a value:
private async static Task<string> GetPin()
{
var taskCompletionSource = new TaskCompletionSource<string>();
CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
async () =>
{
var pin = await UI.GetPin();
taskCompletionSource.SetResult(pin);
}
);
return await taskCompletionSource.Task;
}
And on Android:
private async Task<string> GetPin()
{
var taskCompletionSource = new TaskCompletionSource<string>();
RunOnUiThread(async () =>
{
var pin = await UI.GetPin();
taskCompletionSource.SetResult(pin);
});
return await taskCompletionSource.Task;
}
Maby this is not a "good" practice, but it works.. I leave a message from webSocket, to mainBody instance, where I have a timered reader...
public class C_AUTHORIZATION
{
public Observer3.A_MainPage_cl parentPageInstance; //еще одни экземпляр родителя
public WebSocket x_Websocket;
private string payload = "";
private DateTime nowMoment = DateTime.Now;
public void GET_AUTHORIZED()
{
bitfinex_Websocket= new WebSocket("wss://*****.com/ws/2");
var apiKey = "";
var apiSecret = "";
DateTime nowMoment = DateTime.Now;
payload = "{}";
x_Websocket.Opened += new EventHandler(websocket_Opened);
x_Websocket.Closed += new EventHandler(websocket_Closed);
}
void websocket_Opened(object sender, EventArgs e)
{
x_Websocket.Send(payload);
parentPageInstance.F_messager(payload);
}
void websocket_Closed(object sender, EventArgs e)
{
parentPageInstance.F_messager("L106 websocket_Closed!");
GET_AUTHORIZED();
}
}
public sealed partial class A_MainPage_cl : Page
{
DispatcherTimer ChartsRedrawerTimer;
public bool HeartBeat = true;
private string Message;
public A_MainPage_cl()
{
this.InitializeComponent();
ChartsRedrawerTimer = new DispatcherTimer() { Interval = new TimeSpan(0, 0, 0, 0, 100) };
ChartsRedrawerTimer.Tick += Messager_Timer;
ChartsRedrawerTimer.Start();
}
private void Messager_Timer(object sender, object e)
{
if(Message !=null) //
{
F_WriteLine(Message);
Message = null; //
}
}
public void F_messager(string message) //
{
Message = message;
}
In Xamarin, I got around this by using:
Device.BeginInvokeOnMainThread(() => {
// code goes here
});