ABSTRACT
Larger problem is decomposed into entities using some form of abstraction. The Bulletin Board style is often used with asynchronous components, but as seen here, that is not required. The infrastructure for handling events may be as simple as the one shown here or much more sophisticated, with several components interacting for the distribution of events. The subscription is anonymous, so a component generating an event, in principle, doesn’t know all the components that are going to handle that event. This style supports a very flexible entity composition mechanism, but, like the previous style, in certain cases it may lead to systems whose erroneous behaviors are difficult to trace. The bulletin board concept has seen applications in many other areas. In the 1990s, there was a considerable amount of work in generalizing the concept to all sorts of distributed system infrastructures.
