title: GemFire alternatives and a license question
body: <p>I've just started looking at gemfire. I'm really impressed actually. I'm a little confused by its licensing, there seems to be some indication that some of it is open source? Does anyone have any clear idea? I'm loathed to talk to their sales people. 
  If not, are there any open source alternatives? I can think of a few technologies which offer the same features but not as a whole.</p>