I Event System

ChiTech's event system

We have some elements in ChiTech that follow the Publisher/Subscriber design pattern. The basic functionality is captured with the base classes chi::EventPublisher and chi::EventSubscriber, where multiple subscribers are assigned to a publisher.

Events

Events are implemented as, a conceptually simple, data class chi::Event and has the following members:

• chi::Event::Name()
• chi::Event::Code()
• chi::Event::Parameters()

The latter member is a chi::ParameterBlock supporting anything from simple scalar quantities all the way through to complex hierarchies of data.

System events

Systems events are posted via the chi::SystemWideEventPublisher singleton and serves the purpose of being the central publisher where all events end up, although, some publishers can attempt to handle events before this handler. Events originating from this publisher are:

• "ProgramStart"
• "ProgramExecuted"

Physics events

Physics events are handled via the chi_physics::PhysicsEventPublisher singleton and has the following basic events (although this list will be extended in future):

• "SolverPreInitialize"
• "SolverInitialized"
• "SolverPreExecution"
• "SolverExecuted"
• "SolverPreStep"
• "SolverStep"
• "SolverPreAdvance"
• "SolverAdvanced"

PhysicsEventPublisher interaction with SystemWideEventPublisher

Order of operations and dependencies related to events can be resolved by using different publishers. This is because the event publishers always form a hierarchy with the SystemWideEventPublisher as the base. Any event published by a leaf publisher will ultimately get forwarded to the SystemWideEventPublisher. An example flow of events is shown below: