Excel Automation and Services

Excel exposes an Automation (COM) API that allows other applications to use Excel to create spreadsheets. This works fairly well if those other applications are interactive but some issues present themselves if they are services or command line utilities run by the Windows task scheduler. Those programs don't run in the context of an interactive user log in and Excel misbehaves if they try use it through Automation. Fortunately, it's possible to make this work by making a few configuration tweaks on the machine where the applications will run and by following a few rules when writing those applications.

Configuring the machine

Determine the user account the service or scheduled task will run as

It can be a local or an Active Directory account and may or may not be a member of the machine's Administrators group.

Grant DCOM permissions to the user account

The user account the service or scheduled task will run as needs to have Local Launch and Local Activation permissions for the Microsoft Excel Application DCOM application.

If the user account is a member of the machine's Administrators group, this step may be unnecessary, but it won't hurt to verify that the permissions are in place.

1. Open Adminstrative Tools -> Component Services -> Computers -> My Computer -> DCOM Config.
2. Find Microsoft Excel Application, right-click on it, and select Properties.
3. Go to the Security tab.
4. Change Launch and Activation Permissions to Customize and click Edit.
5. Add the user account and check Local Launch and Local Activation.
6. Click OK.
7. Click OK.

Configure the systemprofile directory

On a 32 bit system, the path of the systemprofile directory is C:\Windows\System32\config\systemprofile\

On a 64 bit system, the path of the systemprofile directory is C:\Windows\SysWOW64\config\systemprofile\

(If you're dealing with a 64 bit system, it might be a good idea to perform the steps below on both the System32 and SysWOW64 sub-directories.)

1. Navigate to the systemprofile directory.
2. Make sure it contains a Desktop sub-directory; create it, if it doesn't exist.
3. Make sure the user account the service or scheduled task will run as has the specified access permissions to the following sub-directories of the systemprofile directory:
   1. AppData\Local\Microsoft: Modify, Read & execute, List folder contents, Read, Write;
   2. AppData\Roaming\Microsoft: Modify, Read & execute, List folder contents, Read, Write;
   3. Desktop: Read & execute, List folder contents, Read;

Using Excel in the application

TODO