Enterprise Server now supports standard ECI calls to Mainframe Subsystem regions. The External Call Interface (ECI) allows non-CICS programs running outside the server to invoke CICS programs within a region opening up access to legacy business logic.
ECI client programs can run on the same machine as the enterprise server and, in this configuration, can communicate across shared memory or through the "Web Services and J2EE" listener. Programs running on different physical hardware submit ECI requests through the listener.