ASP.NET Cannot launch Excel's file on server - asp.net

Question

i'm trying to open launch Excel specifing an existing file to open. This is my code:
Protected Sub fileManager_SelectedFileOpened(source As Object, e As FileManagerFileOpenedEventArgs)
Try
Dim FullName As String = e.File.FullName
System.Diagnostics.Process.Start(FullName)
dvFileError.Visible = False
Catch ex As Exception
dvFileError.Visible = True
lblFileError.Text = ex.Message
End Try
End Sub
In the e.File.FullName i can found the file's name with its path, so when i launch it as process it should open the Excel's file.
So this code works on local, but when i upload it on a web server it not works. It say "An error occurred in sending the command to the application".
I've created a .txt file to test if my application can access to the folder an i take this the "Access is denied" error.
It is strange because if i open the same Excel's file using a ASPxSpreadSheet Control of DevExpress, the file is opened.
Any solutions?

Answer 1

Your web service can't just open an executable on the client in normal circumstances. There's a few exceptions:
Your web server has admin privileges on the client. This typically only happens in a company LAN scenario
Your web service is the same machine as the client.
You have some sort of software running on the client that can launch the program as necessary. This requires technology outside of the web HTML/CSS/JS sandbox of the browser.
You were operating under #2. But as soon as you switch to remote clients that isn't going to work. You can't use System.Diagnostics.Process to start applications on a remote client. And you can't directly access files on the remote clients machines. Your VB.NET code is running on the server, not on the client. Only your HTML/CSS/JS runs on the client, and that's in the limited sandbox of the browser.
The general pattern to accomplish what you want is just offer a file for the user to download by writing the file to an HTTP response. The user can then open the file and it will launch their default program for editing that filetype.

Answer 2

Before I start, I can tell you that this is one of the worst things that you can do - is to run Excel application on the web server.
If you need to read or save Excel file(s) use Microsoft.Ace.OleDb.xx (xx-version). It will allow you to work with Excel as if it was regular DB. Moreover, if in connection string you give file name of the file that doesn't exist, it will create it.
Remember, you're on the server. And your application runs in application pool. The application pool runs under some user account, which may not have permission to open any user interface.
I remember, we had an issue with Windows service and Excel automation. Excel needs the account, which runs it to be literally logged on into machine. In other words, you need to use the credentials of the account that runs the app pool to logon into this machine. Only then Excel automation will work.
In any case. When you do Excel automation first thing you need to do is to open Excel once to get rid of all the dialogs it displays from beginning. And until you click them off, each instance will keep on showing them even if you don't see them or instance.
And last couple words - you need to use some interop assemblies, not just process.start. It will take care of some things. But Microsoft told us - they do not support or recommend Excel automation, although, admit - it is possible. Returning to paragraph #2 - to write or read data do that, not what you do. You can do #2 in IIS process. But don't do automation in process - very bad idea.