Tracking multiple processes at same time

Question

I have an application (winforms) that downloads a file to user's temporary folder, then it opens the file for user to see contents, and when the file is closed, the file gets deleted from temp folder. The application is working ok if I open let's say one .pdf and one .doc The problem appears when trying to open one .doc if another winword process is still runing (doesn't matter if is opened by my app or directly by user).

I'm using the following code:

_OpenFileProces = System.Diagnostics.Process.Start(TempFileName);
_OpenFileProces.EnableRaisingEvents = true;
_OpenFileProces.Exited += new EventHandler(_OpenFileProces_Exited);

and this one to clear temp

void _OpenFileProces_Exited(object sender, EventArgs e)
    {
        string s = ((System.Diagnostics.Process)sender).StartInfo.FileName;
        System.IO.File.Delete(s);
    }

It seems that the running process is stopping my own.. and due to stopping it will delete the file or it will generate an error while trying to delete the file.
Do you have any suggestion how can I open my own process? The thing is I do not know what file type I have to open (it could be anything) and I'm counting on windows to choose the best application. from my test, notepad works ok, but winword and acrobat closes my process.
Thank you

Answer 1

I suspect that Microsoft Word is doing exactly the same thing here as Raymond Chen describes the Windows Shell as doing here:

A customer wanted help with monitoring the lifetime of an Explorer window.

"We want to launch a copy of Explorer to open a specific folder, then wait until the user closes the folder before continuing. We tried launching a copy of Explorer with the folder on the command line, then doing a Wait­For­Single­Object on the process handle, but the wait sometimes completes immediately without waiting. How do we wait until the user closes the Explorer window?"

This is another case of solving a problem halfway and then having trouble with the other half.

The reason that Wait­For­Single­Object returns immediately is that Explorer is a single-instance program (well, limited-instance). When you open an Explorer window, the request is handed off to a running copy of Explorer, and the copy of Explorer you launched exits. That's why your Wait­For­Single­Object returns immediately.

In your case, Word is already running, so when you create a second Word process and instruct it to open your document, it simply hands the request off to the instance of Word that is already running, and quits the second process you launched immediately.

That's what you're seeing when you describe that "the running process is stopping my own". Because that second instance gets closed immediately after you launch it, the Exited event is raised and your code tells it to delete the file!

You astutely observe that Notepad (unlike Word and Adobe Acrobat) works just fine. That's because Notepad is designed to be a multiple-instance application. You can open as many copies of Notepad as you want; it doesn't care if there's already 1 or 6 copies open on the desktop. And more importantly, asking the shell to open a text document in Notepad actually opens a second copy of the Notepad application, rather than sending a request to the first instance to open a new window for the new doc.

Answer 2

You should set the Process.StartInfo.UseShellExecute to true like this _OpenFileProces.StartInfo.UseShellExecute = true; before starting the process and then it should work I think...