Simple! All requests are made using the standard HTTP protocol. There are only 4 verbs: read, write, invoke and meta. The response is pure JSON and contains the value as well as type information. Optionnaly, a timestamp can be added so you can keep track of the evolution of data over time.
Woopsa's simplicity is what distinguishes it from every other industrial protocol out there. However, Woopsa extensions, which are published as regular Woopsa methods, add powerful mechanisms like multiple requests or even the publish/subscribe pattern.
Woopsa is based on solid foundations everybody knows, so it takes very little effort to use it in your own applications.
All it takes to understand what Woopsa can do is to take a look at our "get started" guide and then take a look at the simple UML model.
Once you've got that figured out, you can dig a bit deeper and read our source code — it's free as freedom!
If you're interested, you can also read the complete specifications to the protocol!