Event Manager APIs
The EventManager class enables anonymous publish/subscribe interactions between different software components and contexts in the system. It provides a singleton class which manages the registry of publishers and subscribers in the system and provides loose coupling between them. To subscribe to events/data, a component must register itself with the manager by calling add_subscriber() - which will register a callback function associated with that component for the event/topic provided. All callback functions for a given topic/event are called from the same thread/context - a thread that is started and managed by the EventManager. As noted in a few places, it is recommended to use a (de-)serialization library such as espp::serialization / alpaca for transforming data structures to/from std::vector<uint8_t> for publishing/subscribing.