The Interface Mapping Toolkit enables you to expose existing COBOL applications to separately-written clients, through technologies such as Web Services and EJB. You do this by mapping the entry points and Linkage Section items in the COBOL program onto an external interface, using the Toolkit's graphical user interface. You can then deploy the application as a service under Server Enterprise Edition (in the case of an EJB you also need a Java application server). This makes the application available to any client. A programmer wishing to write a client just needs to know the interface to invoke the service.
When a client makes a request through Web Services or EJB, the COBOL application runs under Server Enterprise Edition. This handles requests coming in through your mapped interface from the client. Server Enterprise Edition passes the requests to the COBOL application to be processed and then returns the response back through the interface to the client.