Allow desktop interaction within Azure Cloud Service with third-party desktop app (automated via code)

Question

Hello,
I am developing a wrapper service as Worker Role which will take request from Service Bus and automate a third-party desktop app to produce an output file and then upload result back to our web server.  The automation is accomplished with the app's
built-in .Net remoting based API.  This all works on my local development machine.  I am using code as below to start the desktop app.  In Azure:
If I am not logged on to RDP and run the app as SYSTEM (or whatever the default WorkerRole account is), it waits forever for the MainWindowHandle.
if I start the app manually in the RDP and try to get a reference to the running process (again as SYSTEM), I get Access Denied from WaitForInputIdle.
if I start the app from code as the RDP user (ProcessStartInfo assign user/pass), I get InvalidOperationException - the app might not have a graphical interface from the WaitForInputIdle.
Could anyone suggest the proper strategy for starting processes in a Worker Role that must create a window?
For reference, I only care about the window to the extent that I need to make sure it's there.  All other interaction with the process is via the .Net Remoting API.
private void GetOrStartThirdPartApp()
_process = Process.GetProcessesByName("ThirdPartApp").FirstOrDefault();
if (_process == null)
_process = new Process();
_process.StartInfo.Arguments = string.Format(@"-I ""{0}""", config.GetSetting("RolePath"));
_process.StartInfo.WorkingDirectory = config.GetSetting("WorkingFolder");
_process.StartInfo.FileName = config.GetSetting("ExecutablePath");
_process.StartInfo.LoadUserProfile = true;
_process.StartInfo.UseShellExecute = false;
if (config.GetSettingAsBoolean("StartThirdPartAppWithRunAs", false))
_process.StartInfo.UserName = "user";
var password = new SecureString();
foreach (var c in "thepassword".ToCharArray())
password.AppendChar(c);
_process.StartInfo.Password = password;
_process.Start();
while (_process.MainWindowHandle == IntPtr.Zero) Thread.Sleep(50);
_process.WaitForInputIdle();
_process.Exited += _process_Exited;

Answer 1

I'd keep the app with the UI and the queue reader in the same process and account - not a worker role.  On start up you launch the desktop application and the queue reader in the same account, one after another.
From what I've experienced, two users don't have the same
Window Stations, so you can't pass a window handle in a different logged-in account across that boundary.  Read the Window Station documentation - you may find something that helps.
You could use other techniques like sockets to communicate cross-process and cross-window station, too.
Darin R.