The buzz around the enterprise services bus (ESB) is growing louder these days. Organizations moving towards service-oriented architectures (SOA) require infrastructure services that provide robust communication, intelligent routing, and sophisticated translation and transformation services. Just as application servers provide connection, transaction, instantiation, and other programming services that freed the programmer from having to write the code for each application, an ESB provides common communication and integration services.

In a recent ebizQ Webinar, “The Enterprise Service Bus: What Should You Do Now?” Roy Schulte, vice president and research fellow at Gartner, stated that “traditional middleware is insufficient to support new applications that use service-oriented architecture (SOA), event-driven architecture (EDA), Web services and business process management (BPM). Architects and IS managers must upgrade the enterprise infrastructure by adding an enterprise service bus (ESB).” Schulte defined SOA as being a two-way request and reply interaction that can be either synchronous or asynchronous, and EDA as a 1-way notification, where a program sends an asynchronous notification to 0…n programs, and no response is required. Loosely coupled EDAs enable more flexibility and scalability. Organizations require both types of interactions, and the middleware needs to support both.

According to Schulte, an ESB “provides communication between distributed components, supports both SOA and EDA, supports Web services, and provides transformation and intelligent content based routing.” Additionally, an ESB may provide support for multiple interfaces in addition to Web services including COM, CICS, .NET, JMS, JCA, and JDBC, and also support distributed operation and management (as opposed to a hub and spoke architecture).

However, while there is general agreement on the core services an ESB provides, there is no general agreement as to whether an ESB is an architecture or a product. Companies such as Software AG, IONA, SeeBeyond, Sonic Software and Fiorano have ESB products positioned as affordable integration solutions particularly well suited for composite applications and SOA. Schulte calls these multi-protocol ESBs. Some ESB vendors, including Cape Clear and Digital Evolution, have focused solely on the Web services market. A third category Schulte defined was “ESB extenders, including KnowNow’s Event Routing, provide EDA support. In the next few years, Schulte predicts the ESB market will converge because companies require multi-protocol solutions, support for Web services and event driven solutions.