Understanding and implementing timers

The HotelGrain class that we have created in the book so far has been getting messages from external clients for welcome greetings or check-in as shown in the following diagram. Ultimately, all the HotelGrain classes have responded to an outside request.

Figure 6.1 – HotelGrain responding to messages from external clients

But what if the grain needs to do some internal processing on a periodic basis. Timers provided by Orleans help in scheduling and creating periodic grain behavior without spanning multiple instances of the grain. Timers are asynchronous, single-threaded, and re-entrant so that a function can fire while the grain is awaiting. A grain can register multiple timers and can also cancel them when it is done with them. Timers are valid for the duration of the grain's activation, so they continue to fire until the grain is deactivated.

Grain.RegisterTimer shown here is the method to register...