Greetings everyone. I am looking for the best way to implement the processing of events from a persistent socket connection. The application will have a persistent socket connection to a device. The communication is base on TCP and I am using a StreamSocket
for this. The communication pattern is as follows:
[MyApp] -- Query Status --> [Device]
<-- Response ---
or
[MyApp] <---- Event ---- [Device] (Something changed on the device)
I have created a Model for the device that is bound to my View (a page). The model implements INotifyPropertyChanged so I expect the controls on the page to change when the properties of the model change.
The problem I have is processing the InputStream because it is persistent and the Device is designed to work this way.
I have looked at the examples such as:
http://code.msdn.microsoft.com/windowsapps/Creating-a-ThreadPool-work-9665cdff
The problem with this example is that it there is not concept of model and view. The worker thread is embedded in the view which would not be practical.
[it would be nice if the StreamSocket or DataReader had an event similar to the StreamSocketListener Connection event so that I didn't need to mess around with background threads and marshalling etc]
What I have done is in the model open a connection and start a worker thread to listen for events:
public async Task Connect(MainPage MainPage)
{
_page = MainPage;
HostName serverHostName = new HostName("xxx.xxx.x.x");
string port = "60128";
try
{
if (_clientSocket != null)
{
_clientSocket.Dispose();
}
_clientSocket = new StreamSocket();
_clientSocket.Control.NoDelay = true;
//connect to the device
await _clientSocket.ConnectAsync(serverHostName, port);
//start the listener thread for reading data on the stream
await Task.Factory.StartNew(ReadDeviceEvents);
}
catch (Exception ex)
{
}
}
private async void ReadDeviceEvents()
{
if (_clientSocket != null)
{
try
{
DataReader reader = new DataReader(_clientSocket.InputStream);
while (true)
{
string c = string.Empty;
//read the eISCP Header
uint sizeFieldCount = await reader.LoadAsync(16);
string sheader = reader.ReadString(16);
ISCPHeader header = new ISCPHeader(sheader);
//read the data
uint dataSize = await reader.LoadAsync(header.DataSize);
string data = reader.ReadString(dataSize);
ISCPResponse response = new ISCPResponse(header, data);
ProcessEvent(response);
}
}
catch (Exception ex)
{
#if DEBUG
System.Diagnostics.Debug.WriteLine("ISCPController.ReadDeviceEvents() - Read Error: " + ex.Message);
#endif
}
}
}
private void ProcessEvent(ISCPResponse response)
{
System.Diagnostics.Debug.WriteLine(string.Format("Event Received CMD {0} PARM {1}", response.Command, response.Parameter));
bool powerOn = false;
if (response.Command.Equals("PWR"))
{
if (response.Parameter.Equals("01"))
{
powerOn = true;
}
Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(
CoreDispatcherPriority.High,
new DispatchedHandler(() =>
{
IsPowerOn = powerOn; //***** I was hoping this would trigger the bindings in the UI but it does not!
_page.ProcessEvent(); /******* I don't want to have to do this. In my model I put a reference to the page to call this method on the page which set the DataContext to the Model again and refreshed the controls. There has to be a better way to do this.
*/
}));
}
}
Is there a better pattern I can implement to listen to the InputStream and process events which update my Model and up date the UI?
