Well, the Internet is full of articles/blogs/code that explain/demonstrate how to model an elevator's functions as a Finite State Machine (FSM). What the heck! I thought of adding one more. :-)

But, my intention is not to repeat the old story. I want to try and model the following, using one elevator as an unit:

• Behaviour of a single elevator (or a lift, as is referred to in my part of the world)
• Controlling its behaviour from a, well, Controller
• Modeling a collection of lifts, as is seen in hotels
• Coordination between these lifts and the controller
• Accounting for h/w devices in the lifts, which send asynchronous signals (messages) to the lifts they are attached to

I don't expect to complete this at one go. Instead, I will build it phase-wise.

The blog is here.

A few hints about various components (may help follow the implementation)

• org.nirmalya.carriages.types.withExplicitMovingState.LiftCarriageWithMovingState

It models the carriage itself; constructed with a TimeConsumingHWSignalSimulator

• org.nirmalya.entities.TimeConsumingHWSignalSimulator

It implements the MovingStateSimulator trait. Specifically, it implements the simulation of spending time while moving to a particular floor (function: simulateMovementTo()).

• org.nirmalya.entities.InlaidButtonPanel

It models a button panel mounted inside a carriage. It is identified by an ID as well as the carriage it is mounted inside. The carriage is an actor; hence, it is constructed with an ActorRef.

• org.nirmalya.entities.LiftController

The Controller in the system. It is constructed with a collection of carriages.