DLL中的主应用程序捕获事件

Question

Here is what I want to do with C# and WPF, but have limited idea how to design and implement:

• The system consists of an dll/assembly (monitor.dll) and a main application (main.exe) .

• monitor.dll is watching a txt file that gets update when some other macro is running. When the txt file is done updating/finish being written, the monitor.dll should release a signal that can be detected by the main.exe.

• The whole process does not have to be frequent. The monitor.dll can check the txt file every quarter second, and the frequency that the main.exe check if the monitor.dll has sent a "done" signal can be on the same order.

I am wondering how should I design the system? What technique should I use? Should I use BackGroundWorker int the assembly?

Right now I am using a timer tick in both the monotor.dll and main.exe, but it seems although the monitor.dll can catch the event, but the main.exe will always not be able to catch the signal sent by the assembly. Thanks.

Answer 1

In the assembly, I used a timer to periodically check the .txt file status, something like this:

System.Timers.Timer _logFileCheckTimer;

    public FijiLauncherControl()

    {        // timer set up
                    _logFileCheckTimer = new System.Timers.Timer(250);  
                    _logFileCheckTimer.Enabled = true;
                    _logFileCheckTimer.Elapsed += new System.Timers.ElapsedEventHandler(_logFileCheckTimer_Elapsed);
                   _logFileCheckTimer.Start();  // start the timer

     }    

     void _logFileCheckTimer_Elapsed(object sender, EventArgs e)
        {
            if (_processOn && IsLogOn)
            {
                try
                {
                    _processFinished = CheckStatuts();  // checking file status

                    if (_processFinished) // fire event if checking status returns true
                    {
                        OnIjmFinished(EventArgs.Empty);
                        _processOn = false;
                        _logFileCheckTimer.Stop();
                    }
                }
                catch (Exception ex)
                {

                }
            }
        }

In the aseembly. setup a event in the dll that will be triggered if the _processFinished = CheckStatuts(); returns true :

// event delegate public delegate void IjmFinishedEventHandler(object sender, EventArgs e); public event IjmFinishedEventHandler IjmFinished; // event handler

   protected virtual void OnIjmFinished(EventArgs e)
   {
      if (IjmFinished != null)   // trigger event
                IjmFinished(this, e);          
   }

In the main application, there should be event receiver, something like this:

private FijiLauncherControl _fl; // the object of your assembly

  _fl.IjmFinished += new IjmFinishedEventHandler(_fl_IjmFinished); // event from the assembly should trigger an event handler

   void _fl_IjmFinished(object sender, EventArgs e)   // event handler
        {
            _vm.IjmFinished = true;   // a boolean var in viewmodel in main app set to be true once the event from the assembly is triggered

            //throw new NotImplementedException();
        }

That should do the job.