All application integrations fall into one of the following three patterns: database consistency relationships, multi-step processes and composite application patterns. Developers need to understand all three basic integration patterns use one (or more) of them as required based on the requirements of the final application.
Traditional integration is performed using a variety of point-to-point communication mechanisms using an architecture where the end-point applications are smart but the network isn't.
Modern business applications are assembled by combining a set of reusable, independently developed business components. Business Component Architecture offers several advantages over traditional application design approaches.
An ESB is a middleware platform that supports intelligent routing of information between business components distributed across a network. Unlike other platforms, ESBs support both request/ reply as well as event-driven interactions between business components on a single technology base with a shared component model and common tools for design, development, deployment, security and administration.