ABSTRACT
An ESB provides an implementation backbone for a SOA that treats applications as services. The ESB is about configuring applications rather than coding and hardwiring applications together. It is a lightweight infrastructure that provides plug-and-play enterprise functionality. It is ultimately responsible for the proper control, flow, and even translations of all messages between services, using any number of possible messaging protocols. An ESB pulls together applications and discrete integration components to create assemblies of services to form composite business processes, which in turn automate business functions in an enterprise. It establishes proper control of messaging as well as applying the needs of security, policy, reliability, and accounting, in an SOA architecture. With an ESB SOA implementation, previously isolated ERP, CRM, supply chain management, and financial and other legacy systems can become SOA enabled and integrated more effectively than when relying on custom, point-to-point coding or proprietary EAI technology. The end result is that with an ESB, it is then easier to create new composite applications that use pieces of application logic and/or data that reside in existing systems.
