Dehydration is a situation when the orchestration has been idle for a while, the orchestration engine will save the state information of the instance and free up memory resources
Rehydration is a message when received or else when a timeout has expired, the orchestration engine can be automatically triggered to rehydrate the instance – it is that point that the orchestration engine loads the saved instance of the orchestration into memory, restores the state and runs it’s from the point it left off.