Publisher is a generic interface to encapsulate how we want our publishers to behave.

Reply is a generic interface to encapsulate how the reply part of request-reply communication will behave.

ReplyMessage is a struct to encapsulate a reply message from a request reply conversation.

Request is generic interface to encapsulate how the Request part of point to point request-reply communication will behave.

Subscriber is a generic interface to encapsulate how we want our subscribers to behave.

SubscriberMessage is a struct to encapsulate subscriber messages and provide a mechanism for acknowledging messages _after_ they've been processed.