Open a URL in a new browser process

Question

I need to open a URL in a new browser process. I need to be notified when that browser process quits. The code I'm currently using is the following:

        Process browser = new Process();
        browser.EnableRaisingEvents = true;
        browser.StartInfo.Arguments = url;
        browser.StartInfo.FileName = "iexplore";

        browser.Exited += new EventHandler(browser_Exited);

        browser.Start();

Clearly, this won't due because the "FileName" is fixed to iexplore, not the user's default web browser. How do I figure out what the user's default web browser is?

I'm running on Vista->forward. Though XP would be nice to support if possible.

A bit more context: I've created a very small stand-alone web server that serves some files off a local disk. At the end of starting up the server I want to start the browser. Once the user is done and closes the browser I'd like to quit the web server. The above code works perfectly, other than using only IE.

Thanks in advance!

Answer 1

Ok. I now have working C# code to do what I want. This will return the "command line" you should run to load the current default browser:

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Linq;
using System.Text;

namespace testDefaultBrowser
{
    public enum ASSOCIATIONLEVEL
    {
        AL_MACHINE,
        AL_EFFECTIVE,
        AL_USER,
    };

    public enum ASSOCIATIONTYPE
    {
        AT_FILEEXTENSION,
        AT_URLPROTOCOL,
        AT_STARTMENUCLIENT,
        AT_MIMETYPE,
    };

    [Guid("4e530b0a-e611-4c77-a3ac-9031d022281b"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IApplicationAssociationRegistration
    {
        void QueryCurrentDefault([In, MarshalAs(UnmanagedType.LPWStr)] string pszQuery,
        [In, MarshalAs(UnmanagedType.I4)] ASSOCIATIONTYPE atQueryType,
        [In, MarshalAs(UnmanagedType.I4)] ASSOCIATIONLEVEL alQueryLevel,
        [Out, MarshalAs(UnmanagedType.LPWStr)] out string ppszAssociation);

        void QueryAppIsDefault(
            [In, MarshalAs(UnmanagedType.LPWStr)] string pszQuery,
            [In] ASSOCIATIONTYPE atQueryType,
            [In] ASSOCIATIONLEVEL alQueryLevel,
            [In, MarshalAs(UnmanagedType.LPWStr)] string pszAppRegistryName,
            [Out] out bool pfDefault);

        void QueryAppIsDefaultAll(
            [In] ASSOCIATIONLEVEL alQueryLevel,
            [In, MarshalAs(UnmanagedType.LPWStr)] string pszAppRegistryName,
            [Out] out bool pfDefault);

        void SetAppAsDefault(
            [In, MarshalAs(UnmanagedType.LPWStr)] string pszAppRegistryName,
            [In, MarshalAs(UnmanagedType.LPWStr)] string pszSet,
            [In] ASSOCIATIONTYPE atSetType);

        void SetAppAsDefaultAll(
            [In, MarshalAs(UnmanagedType.LPWStr)] string pszAppRegistryName);

        void ClearUserAssociations();
    }

    [ComImport, Guid("591209c7-767b-42b2-9fba-44ee4615f2c7")]//
    class ApplicationAssociationRegistration
    {
    }

    class Program
    {
        static void Main(string[] args)
        {
            IApplicationAssociationRegistration reg = 
                (IApplicationAssociationRegistration) new ApplicationAssociationRegistration();

            string progID;
            reg.QueryCurrentDefault(".txt",
                ASSOCIATIONTYPE.AT_FILEEXTENSION,
                ASSOCIATIONLEVEL.AL_EFFECTIVE,
                out progID);
            Console.WriteLine(progID);

            reg.QueryCurrentDefault("http",
                ASSOCIATIONTYPE.AT_URLPROTOCOL,
                ASSOCIATIONLEVEL.AL_EFFECTIVE,
                out progID);
            Console.WriteLine(progID);
        }
    }
}

Whew! Thanks everyone for help in pushing me towards the right answer!

Answer 2

If you pass a path of the known file type to the (file) explorer application, it will 'do the right thing', e.g.

 Process.Start("explorer.exe", @"\\path.to\filename.pdf");

and open the file in the PDF reader.

But if you try the same thing with a URL, e.g.

Process.Start("explorer.exe", @"http://www.stackoverflow.com/");

it fires up IE (which isn't the default browser on my machine).

I know doesn't answer the question, but I thought it was an interesting sidenote.