What is the proper way to determine an application's location?

Question

I'm writing a windows service in C# that spawns multiple instances of another application I am writing. There is a chance that the application can be installed anywhere on a machine. What is the best way to let the service know where the application is located?

Answer 1

If you need to locate the folder your service is installed to you can use the following code

this.GetType().Assembly.Location

If you need to locate the folder some other application is installed to you should make a request to windows installer

[DllImport("MSI.DLL", CharSet = CharSet.Auto)]
private static extern UInt32 MsiGetComponentPath(
    string szProduct,
    string szComponent,
    StringBuilder lpPathBuf,
    ref int pcchBuf);

private static string GetComponentPath(string product, string component)
{
    int pathLength = 1024;
    StringBuilder path = new StringBuilder(pathLength);
    MsiGetComponentPath(product, component, path, ref pathLength);
    return path.ToString();
}

Answer 2

If you mean that the service starts a different app, then; options:

• configure the service with a config file; put the path in there
• put something in the registry during installation
• use something akin to COM/COM+ registrations
• consider the GAC if the other app is .NET (although I'm not a fan...)
• environment variable?

Personally, I like the config file option; it is simple and easy to maintain, and allows multiple separate (side-by-side) service and app installs