What is a Command Bus?

Question

It seems many implementations of CQRS implement a mechanism called Command Bus, which is used for subscribing handlers to command.

a) Is Command Bus an implementation of Distributed Command pattern or perhaps a Message Bus pattern?

b) I've also noticed the term Message Bus being used in reference to CQRS. Are Message Bus and Command Bus just different names for the same mechanism or are the two different?

thanks

Answer 1

The CommandBus is the MessageBus which you use to send Commands. It implies that there is another implementation of a MessageBus for handling other types of Messages.