C# external tool for SSMS - Reading from stdin

Question

Hi all,

I am trying to write an app that makes use of the external tools functionality of SQL Server Management Studio.

To specify an external tool, you can enter a path to the app and specify some arguments to pass to the app via STDIN.

Currently I just have a form that displays the arguments. Every time I run the external tool I get a new instance of the application.

Ideally I would like for the first time I run the tool to load the application, and each subsequent running to take the arguments from STDIN and do something with them WITHOUT creating a new instance of the app.

Is there anything I can do that could allow this, or am I stuck with lots of windows?

Thanks in advance

Answer 1

As horrible as it sounds, you can leverage Microsoft.VisualBasic.ApplicationServices to make this really simple (you can add a reference to Microsoft.VisualBasic in your c# project).

As a quick example, you can create a new C# WinForms project and alter Program.cs to look something like this:

class Program : WindowsFormsApplicationBase
{
    static Form1 mainForm = null;

    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main(string[] commandline)
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Program prog = new Program();
        prog.MainForm = mainForm = new Form1();
        prog.Run(commandline);
    }

    public Program()
    {
        this.IsSingleInstance = true;
    }

    protected override void OnStartupNextInstance(StartupNextInstanceEventArgs eventArgs)
    {
        base.OnStartupNextInstance(eventArgs);
        mainForm.Startup(eventArgs.CommandLine.ToArray());
    }
}

Then in the Form1 throw a label on there and a little code to show it's working:

    public void Startup(string[] commandLine)
    {
        string output = "";
        foreach (string arg in commandLine)
            output += arg + "\n";

        label1.Text = output;
    }

    public Form1()
    {
        InitializeComponent();
        Startup(Environment.GetCommandLineArgs());
    }

The only gotcha with this little snippet is that the command line arguments you get on first launch include the application name, but it's not included on subsequent launches.