Here is the setup: I plan to stand up an instance of Exchange Server so that I can integrate an existing Ruby on Rails app with it for a proof of concept project. I'm looking to allow users of the Ruby on Rails app to see when a different user is available via the app (not via Outlook).
Here is what I want to know:
1. MSDN with Exchange is really expensive and so is Exchange Server. Is there an option that exists to use Exchange Server as a developer or under lab conditions that is inexpensive?
2. Is there a hosted instance of exchange or host of exchange that I could work with that my Ruby on Rails application could interface with via a web service or API?
3. I would really like to be able to do more than just pull availability, but that is all that is needed.
4. Would it make sense to buy an older version of Exchange (e.g. 5.5, 2003, 2007) instead of Exchange 2010 and just use that? It sounds like no.
Any suggested reading would be a plus.