Business Model of Future Exchange

I am new to commodity trading but  I have deep interest in the commodity trading. I want to understand the exact business model of Future exchanges, how are they making money? other than providing a common platform and gaurantee through clearing house what are they providing to their clientele?

Is there any possibilty to shift the clients of OTC market into fture market? or like ICE ,providing the OTC trading is the only solution? This is my first post on this forum and I am asking so many question but untill and unless, I understand the business how can I invest in that.

I will appreciate if you share your knowledge and provide me valuable insights.