c# register commandline argument don't start new instance

Question

Application c:\pinkPanther.exe is running and it is application i wrote in c#. Some other application starts c:\pinkPanther.exe purpleAligator greenGazelle OrangeOrangutan and i would like not to start new instance of c:\pinkPanther.exe with these arguments, but to currently running c:\pinkPanther.exe register it and react to it somehow.

How to do it?

EDIT!!!: i'm very sorry about pinkPanther.exe and ruzovyJeliman.exe that caused the confusion - i translated question from my native language and missed it :(

Answer 1

This is assuming your application is a WinForms app, as that will make it easier to keep it open. This is a very simple example, but it will show you the basics:

1. Add a reference to Microsoft.VisualBasic.

2. Create an Application class inheriting from WindowsFormsApplicationBase. This base class contains built-in mechanisms for creating a single-instance application and responding to repeated calls on the commandline with new arguments:

   using Microsoft.VisualBasic.ApplicationServices;
   
   //omitted namespace
   public class MyApp : WindowsFormsApplicationBase {
       private static MyApp _myapp;
   
       public static void Run( Form startupform ) {
           _myapp = new MyApp( startupform );
   
           _myapp.StartupNextInstance += new Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventHandler( _myapp_StartupNextInstance );
   
           _myapp.Run( Environment.GetCommandLineArgs() );
       }
   
       static void _myapp_StartupNextInstance( object sender, Microsoft.VisualBasic.ApplicationServices.StartupNextInstanceEventArgs e ) {
           //e.CommandLine contains the new commandline arguments
           // this is where you do what you want with the new commandline arguments
   
           // if you want it the window to come to the front:
           e.BringToForeground = true;
       }
   
       private MyApp( Form mainform ) {
           this.IsSingleInstance = true;
           this.MainForm = mainform;
       }
   }
   

3. All you have to change in Main() is call Run() on your new class rather than Application.Run():

   static class Program {
       [STAThread]
       static void Main() {
           Application.EnableVisualStyles();
           Application.SetCompatibleTextRenderingDefault( false );
           MyApp.Run( new MyMainForm() );
       }
   }
   

WindowsFormsApplicationBase has some other capabilities you can explore, as well.

Answer 2

To communicate with the other instance of the application, you need some sort of inter-process communication. Apparently, WCF is the recommended form of IPC in .Net. You can do that with code like this (using WPF, but WinForms would be similar):

[ServiceContract]
public interface ISingletonProgram
{
    [OperationContract]
    void CallWithArguments(string[] args);
}

class SingletonProgram : ISingletonProgram
{
    public void CallWithArguments(string[] args)
    {
        // handle the arguments somehow
    }
}

public partial class App : Application
{
    private readonly Mutex m_mutex;
    private ServiceHost m_serviceHost;
    private static string EndpointUri =
        "net.pipe://localhost/RuzovyJeliman/singletonProgram";

    public App()
    {
        // find out whether other instance exists
        bool createdNew;
        m_mutex = new Mutex(true, "RůžovýJeliman", out createdNew);

        if (!createdNew)
        {
            // other instance exists, call it and exit
            CallService();
            Shutdown();
            return;
        }

        // other instance does not exist
        // start the service to accept calls and show UI
        StartService();

        // show the main window here
        // you can also process this instance's command line arguments
    }

    private static void CallService()
    {
        var factory = new ChannelFactory<ISingletonProgram>(
            new NetNamedPipeBinding(NetNamedPipeSecurityMode.None), EndpointUri);

        var singletonProgram = factory.CreateChannel();
        singletonProgram.CallWithArguments(Environment.GetCommandLineArgs());
    }

    private void StartService()
    {
        m_serviceHost = new ServiceHost(typeof(SingletonProgram));
        m_serviceHost.AddServiceEndpoint(
            typeof(ISingletonProgram),
            new NetNamedPipeBinding(NetNamedPipeSecurityMode.None),
            EndpointUri);

        m_serviceHost.Open();
    }

    protected override void OnExit(ExitEventArgs e)
    {
        if (m_serviceHost != null)
            m_serviceHost.Close();

        m_mutex.Dispose();
        base.OnExit(e);
    }
}