Technical Specifications for Excel Connect

This article describes where the Excel Connect add-in is installed on the user’s PC, and how the .xll files are presented on the user’s system. The Excel Connect add-in installs in the user’s “Roaming” path (%USER%/AppData/Roaming (i.e. a per-user install)), which allows the Excel application to add to its function library and run-time workflows. This allows us to not require users to have admin privileges on their machine (problematic for larger organizations). This is since Excel Connect writes only to files the user owns (rather than to Program Files), and to the user hive in the registry (which, again, the user owns). 

Registry access is necessary for two things:

1. Registration within the Roaming folder allows Excel to load the .xll files automatically, rather than requiring the user to perform any manual actions
2. Efficient installation into a recognized file directory so that the add-in can be updated, removed or repaired as necessary

The installed directory structure for an add-in is as follows:

```
%USER%\AppData\Roaming\Alpha Theory\
└── Alpha Theory Excel Add-in\
    |   AddInReloaderConfiguration.xml
    |   AlphaTheoryExcelAddInManager.xll
    |   AlphaTheoryExcelAddInManager64.xll
    └── [AddInName]\
        |   manifest.xml
        └── [version number]\
            |   manifest.xml
            |   [AddInName].xll
            |   [AddInName]64.xll