JCAPS stands for
Java
Composite
Application
Platform
Suite. It's not an application server, but a set of tools covering several development targets. Some of the domains that are covered include data transformation (eGate), business process management (eInsight), B2B transaction management (
eXchange Integrator), and so on.
Previous releases of these tools have been around for some time under different names. Sun Microsystems bought the founding company (SeeBeyond Technology) a while back and has since been re-packaging many of these tools to use well-known standards (
J2EE, Web Services, etc.) and message protocols (HIPAA, EDIFACT, ebXML, etc).
The software release happens to include an Integration Server, which in the current releases is a modified Sun
Java Application Server, Platform edition component. The toolset also includes a design tool (based on NetBeans) and a management server with a browser-based interface.