CBSE emphasizes the separation of concerns with respect to the wide-ranging functionality available throughout a given software system. It is a reuse-based approach to defining, implementing and composing loosely coupled independent components into systems.
What is a component?
A piece of software that is connected to other only through its interfaces.
An "interface" is an element that exposes a communication channel with a known contract
Development roles
System architect (defines the requirements)
Component designer (implements components)
System integrator (composes components)
Communication Pattern: request-reply
A server port provides an interface.
0-to-N clients send requests to server.
The only purpose of the server is to provide answers (replies) as quickly as possible.
Request can be either synchronous (wait for an answer) or asynchronous (don't wait, poll).
Server must NOT make any assumption about clients.
Communication Pattern: publish-subscribe
A publisher exposes data (the topic).
0-to-N subscribers notifies that they want to receive the data.
Publisher must NOT make any assumption about subscribers.
The interface is always asynchronous for the publisher and might be either SYNC or ASYNC for the subscriber.
Good components have:
Strongly typed interfaces
Explicitly documented contracts
As little state as possible
A well defined functionality
An implementation that allow deployment to be configured by the integrator.
