Features of the ESB include a pluggable architecture for swapping out ESB subsystems, support for messaging services such as secure FTP and HTTP and a transformation engine bridging data formats. XSLT (Extensible Stylesheet Language Transformations) and the Smooks transformation engine for XML and non-XML data formats are supported.

A service registry is featured for service discovery and integration, using JAX-R (Java API for XML Registries) and UDDI. Content-based routing is provided based on XPath and JBoss Rules.

JBoss business partner SeeWhy Software plans to use the ESB to channel data to its real-time business intelligence platform for SOA. "The ESB is providing basically an event stream onto our service endpoints," said Charles Nicholls, CEO of SeeWhy in the United Kingdom. "In essence, it is providing streams of events for event stream processing."

A release candidate of JBoss ESB 4.0 is available . A final community-oriented release is available in December. A version of the JBoss ESB supported by the company itself is due in 2007.

As part of its upcoming JBoss Application Server 5.0 release, JBoss has been making available components of that release that can be used with the existing JBoss Application Server Version 4.0.5. JBoss Application Server 5.0 would comply with the Java Platform Enterprise Edition 5.0 standard.