To call an existing COBOL server
Use the IDL Extractor for COBOL to extract the Software AG IDL and, depending on the complexity, also a server mapping file. See When is a Server Mapping File Required? under Server Mapping Files for COBOL in the Designer documentation.
Build an EntireX RPC client using any EntireX wrapper. See EntireX Wrappers. For a quick test you can:
use the IDL Tester; see EntireX IDL Tester in the Designer documentation
generate an XML mapping file (XMM) and use the XML Tester for verification; see EntireX XML Tester in the XML/SOAP Wrapper documentation
See Server Examples for z/OS IMS MPP in the COBOL Wrapper documentation for COBOL RPC Server examples.