ESA, Enterprise Services Architecture offers a sound, flexible architecture for adapting business processes in response to changing market conditions. Harnessing web services, EDI and legacy applications, has become the goal of most modern organizations. SOA (service-oriented architecture) under ESA can simplify the creation and maintenance of large-scale applications. When a project involves a large set of web services-based components, or connects legacy applications to modern business processes, knowledge of ESA and SOA can create a structured approach to managing and designing future business applications.