Date Added: May 2010
The event-based software architectural style is widely used in the domain of user-interface software and wide-area applications (e.g., financial markets, logistics, and sensor networks). A Gartner study determined that the market size for message-oriented (a.k.a event-based) middleware licenses was about $1 billion in 2005. In event-based systems, components do not directly call other components, but rather indirectly using messages or events. However, this high decoupling and use of implicit invocations render an event-based system more difficult to analyze since, in the absence of explicit dependency information, an engineer has to assume that any component in the system may potentially interact with, and thus depend on, any other component.