Service-Oriented Architecture (SOA) is fast becoming the systems and software approach of choice for the majority of medium and large enterprises. According to the principles of SOA, IT professionals design, implement, and deploy information systems from components that implement discrete business functions. These components, called ?services?, can be distributed across geographic and organizational boundaries, can be independently scaled and can be reconfigured into new business processes as needed. This flexibility provides a range of benefits for both the IT and business organizations.

Core to the IT infrastructure supporting SOA is the Enterprise Service Bus (ESB), which connects, mediates and controls all communications and interactions between services and provides error and exception processing. ESBs have been chosen as the best method for development and deployment of processes, ensuring reliability and ultimately success with the introduction and operation of SOAbased systems. Its design permits rapid change in services and in the connections among services, and provides the management visibility into services and processes across a distributed environment.

When looking at the cost of infrastructure and change in development and deployment processes, as well as ultimate performance and reliability of SOA projects, key questions arise with regards to technology, management, and skills transfer. These questions include:

  • How do I build processes which span new service-enabled applications as well as existing legacy systems?

  • How do I provide the performance expected of enterprise systems while easily accommodating changes in demand?

  • How do I isolate applications from faults resulting from server and communication failures?

  • How do I manage processes that will interact with services spread across an organization, and between organizations?

  • How do I manage and monitor the infrastructure, as well as the processes and services deployed within it?

  • How do I allow the organization to change processes, rules, data mapping and relationships between applications with minimal effort and disruption?


Sonic ESB (hereafter referred to simply as "ESB") sets a reference mark for the SOA marketplace with which to examine these questions. The ESB is complemented by additional products in the Sonic SOA infrastructure family including Sonic Workbench, Orchestration Server, XML Server, Collaboration Server, and Database Server.

Given the power of an ESB to support SOA implementations it is imperative to understand in detail the functions and structure of the ESB. This paper will describe each of the key ESB functional areas through exposition of its function and benefits accompanied by conceptual structure diagrams based on an industry-standard approach, UML (Unified Modeling Language). The use of UML diagrams provides a conceptual view of the ESB components - and is useful for learning and discussion of the ESB mechanism. Other diagram provided in this document employ ESB notation from David Chappell's book Enterprise Service Bus and are used to depict examples of more expansive ESB use cases.

Continued in the attached document.

esb_architecture_definition.pdf