Unfortunately, this is the dead end. I have found what this software is and why it will never give me the functionality I want.
First of all, Boeing have developed a Free-Busy connector for Exchange, not a complete CalDAV proxy. This is a web application (an ASP by the way) which takes someones e-mail as an input and returns their Free-Busy information in a format compatible with some CalDAV servers. I have tried using it with Bedework CalDAV server and I found it absolutely useless. This is a very good first attempt, but there are the following shortfalls:
- You need to run this special connector service, and you need to run it on a Windows machine.
- This initial implementation does not have any built-in security. It just accesses the Exchange server through one preconfigured account. You canot use different users for different requests
- This will only allow you to see whether email@example.com is free or busy from 9am to 10am, but would not let John know if you are busy.
- This example service in not available in the wild.
On the other hand, this is a good first step towards integration with Exchange. If the community demonstrates any interest, there will be someone to make further road.