In my previous entry, you heard a little about the trouble of installing into the GAC without using MSIs. I just found some useful information about choices with interop libraries for Outlook from here.

This article illustrates a few interesting things! If you are writing an Outlook addin, you have a few choices:

  1. Write your addin exclusively for Outlook 2003 and use the Office 2003 PIA
  2. Write your addin for multiple versions of Outlook and use the Office XP PIA
  3. Write code to custom load PIAs at runtiume

#3 is no small amount of work. #1 doesn’t make sense for anyone other than Microsoft. Microsoft wants everyone to use the latest version (and upgrade), so they love this option. For the rest of us, that actually want a reasonably sized user base to draw from, you’ve got to use option #2.

And, the XP PIA has a number of known bugs – only fixed in the 2003 PIA. For instance, I ran into this bug the hard way. There is no fix unless you are using Outlook 2003.


On the good news front, I am glad that folks from Microsoft (like Omar, mentioned above) are helping to document this stuff along the way.