The OS/390® Unix Systems Services DCE Application Support MVS/ESA CICS® Feature 4 enables a DCE client application anywhere in the DCE environment to access the resources of a CICS system. The client program uses the simple DCE Remote Procedure Call (RPC), or the DCE Transactional Remote Procedure Call (TRPC), mechanism to call a CICS application program.
The client program does not need to know where the required CICS application is located. Functions of the Application Support server and the OS/390 Unix Systems Services DCE Base Services MVS/ESA product (OS/390 Unix DCE Base MVS/ESA) provide the location information. When the client and server are on different systems, the differences are transparent to the application programmer.
The Application Support server supports client programs written in C, and CICS application programs written in COBOL. The Application Support server automatically handles the conversions of the COBOL and C data types. Components of OS/390 Unix DCE Base MVS/ESA handle conversions of EBCDIC and ASCII data types, if needed.
Thus the Application Support server provides the powerful CICS application environments on the host, and the familiar (to the client workstation programmer) C language and RPC mechanism on the client.
The Application Support server:
The CICS server programs are called operations. Each RPC requests the execution of one operation. The declarations for each operation, including the specifications for the input and output parameters, are contained in an interface definition. You define one or more related operations in an interface, using the Interface Definition Language (IDL).
IDL defines the server functions that a client can call. IDL is a declarative language with syntax similar to the C language. The Application Support server contains IDL extensions that enable a programmer to use COBOL syntax to define the parameters for the CICS application programs. The programmer coding the IDL declarations may be a COBOL or a C programmer.