Start 2nd instance of a c# program with a parameter, which the 1st instance of the program uses

I have a single instance program, which when it runs I can choose to pass a single parameter to it.

If the program runs with no parameters, just opens up on a tab a dataGridView and loads a list of customers into it. If I double click a row it opens up that particular customer in a 2nd tab with more info on it.

If I start the program with a parameter, (a customer id number from 00000 to 99999) it automatically switches to the 2nd tab and loads that individual customers data.

So far so good, however, What I want to be able to do is have my program running, but if a 2nd instance of the program is called with a parameter, e.g. Program.exe 1234, I want it to just jump straight to the 2nd tab and display that customer's details.

This is what I have so far. Am I barking up the wrong tree with the way I'm trying to do this? I get the impression the Program.exe should be listening for another instance running and using the parameter passed to it.

Any advice would be greatly appreciated.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Text;
using System.Diagnostics;
using System.Threading;
using System.Reflection;
using System.IO;


namespace SiteConnex
{
    public class SingleApplication
    {
        /// Imports
        [DllImport("user32.dll")]
        private static extern int ShowWindow(IntPtr hWnd, int nCmdShow);
        [DllImport("user32.dll")]
        private static extern int SetForegroundWindow(IntPtr hWnd);
        [DllImport("user32.dll")]
        private static extern int IsIconic(IntPtr hWnd);
        public static bool secondInstance = false;
        public static string siteid = "";
        public static bool gotosite = false;

    public static void Main(string[] args)
    {
        // string siteid = "";
        // bool gotosite = false;
        // bool secondInstance = false;
        int testSiteid = 0;
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);

        try
        {
            siteid = Convert.ToString(args[0]);
        }
        catch (Exception noArgs)
        {
            // No commandline args have been passed.
        }


// check that the parameter passed is actually a valid number, otherwise just act like no params passed.
            try
            {
                testSiteid = Convert.ToInt32(siteid);
                if ((testSiteid > 00000) || (testSiteid < 99999))
                {
                    gotosite = true;
                }
                else
                {
                    siteid = "";
                }
            }
            catch (Exception e)
            {
                // If you get an exception it means siteid had duff data passed into it.
            }

        /// Check if it's running, if it is, pass siteid and gotosite through... and acts as if it has a valid siteid passed to it. 
        // Application.Run(new Form1(siteid, gotosite));
        Run(siteid, gotosite, secondInstance);
    }

    private static IntPtr GetCurrentInstanceWindowHandle()
    {
        IntPtr hWnd = IntPtr.Zero;
        Process process = Process.GetCurrentProcess();
        Process[] processes = Process.GetProcessesByName(process.ProcessName);
        foreach(Process _process in processes)
        {
            // Get the first instance that is not this instance, has the
            // same process name and was started from the same file name
            // and location. Also check that the process has a valid
            // window handle in this session to filter out other user's
            // processes.

            if (_process.Id != process.Id &&
            _process.MainModule.FileName == process.MainModule.FileName &&
            _process.MainWindowHandle != IntPtr.Zero)
            {
                hWnd = _process.MainWindowHandle;
                break;
            }
        }
        return hWnd;
    }


    /// SwitchToCurrentInstance

    private static void SwitchToCurrentInstance(string siteid, bool gotosite, bool secondInstance)
    {
        IntPtr hWnd = GetCurrentInstanceWindowHandle();
        if (hWnd != IntPtr.Zero)
        {
        // Restore window if minimised. Do not restore if already in
        // normal or maximised window state, since we don't want to
        // change the current state of the window.
            if (IsIconic(hWnd) != 0)
            {
                ShowWindow(hWnd, SW_RESTORE);
            }
            // Set foreground window.
            SetForegroundWindow(hWnd);
            secondInstance = true;
        }
    }
        /// Execute a form base application if another instance already running on
        /// the system activate previous one
        /// <param name="frmMain">main form</param>
        /// true if no previous instance is running

    // public static bool Run(System.Windows.Forms.Form frmMain)
    public static bool Run(string siteid, bool gotosite, bool secondInstance)
    {
        if(IsAlreadyRunning())
        {
          开发者_C百科  //set focus on previously running app   
            SwitchToCurrentInstance(siteid, gotosite, secondInstance);
            return false;
        }
        Application.Run(new Form1(siteid, gotosite, secondInstance));
        return true;
    }
        /// check if given exe alread running or not
        /// returns true if already running

    private static bool IsAlreadyRunning()
    {
        string strLoc = Assembly.GetExecutingAssembly().Location;
        FileSystemInfo fileInfo = new FileInfo(strLoc);
        string sExeName = fileInfo.Name;
        bool bCreatedNew;   
        mutex = new Mutex(true, "Global\\"+sExeName, out bCreatedNew);
        if (bCreatedNew)
        mutex.ReleaseMutex();   
        return !bCreatedNew;
    }
    static Mutex mutex;
    const int SW_RESTORE = 9;
}

}

Ah ha... found the answer in this... Someone called MadHatter made an SingleInstance app that does exactly what I was looking to do and seems fairly straight forwards.

http://sanity-free.org/misc/SingleInstanceApp.zip