You need to write some Java client software to call the generated EJB or Java bean and to pass it the parameters required for the COBOL service. This client software might be a JSP or a servlet or some other module.
The EJB or Java bean interface is defined in the Interface Mapping Toolkit. Typically, you find out the interface by importing the EJB or Java bean into a Java development tool and investigating the interface there. One point to note is with regard to output parameters. If the mapped interface passes multiple output parameters (rather than using a group item and its corresponding custom record), the output parameters are returned through a container object in the EJB or Java bean interface. You can see this in your Java development tool.
At run time, the Java client software calls the EJB or Java bean. The EJB passes the request to the resource adapter, which communicates with the enterprise server to execute the COBOL service. The Java bean communicates with the enterprise server directly.