Provide high level view of the different components

[smcvb]

@ghilainm documented this request under the AxonFramework repository, issue number #712. The contents have been copied over here per direct reference.

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The link between the different components is not clear for me. Would it be possible to add in the documentation an overview with a component diagram illustrating how the following components are linked:

EventStore
EventBus
EventProcessor
EventHandler
MessageSource
ProcessingGroup
TokenStore
TrackingToken

It seems sometimes to me that the concept of EventBus/EventStore/EventProcessor overlaps in your documentation which makes it quite confusing when reading it.

Maybe the diagram in architecture overview section should be clarified a bit to provide a bit more context or add a section grouping definitions of those context.

[smcvb]

To provide a quick and short answer for your 'overlap between concepts'.

The EventStore is a specification of the EventBus, with the added notion of it storing events. Thus, an EventStore is an EventBus by definition in the framework.

The EventProcessor is completely different from the EventBus/EventStore, as it is the business part to handling the events instead of publishing the events.