Introduction to ONC RPC

CICS®ONC RPC allows client applications to access CICS programs by calling them as remote procedures using the ONC RPC format.

CICSONC RPC can be used:
  • To allow clients to use existing CICS programs and the transaction processing services they provide
  • To allow clients to use newly created CICS programs

TCP/IP for MVS™ is a prerequisite for CICS ONC RPC; it provides the library code for Sun Microsystems ONC RPC Version 3.9. Hence, CICS ONC RPC servers work with any remote client compatible with ONC RPC Version 3.9, regardless of operating system or machine type. For information about the function of ONC RPC Version 3.9 supported by TCP/IP for MVS, see z/OS Communications Server: IP Programmer's Guide and Reference.

Figure 1shows how CICS ONC RPC allows a variety of client applications to communicate with CICS programs using ONC RPC.
Figure 1. How CICS ONC RPC might be used
Diagram showing an OS/390 server system containing a CICS Transaction Server region. A CICS program in the CICS region makes a call that is passed to CICS ONC RPC, which passes the call to TCP/IP for MVS, which in turn propagates the request over the network to remote clients.
The CICS program called to service a client request is executed by a transaction that has no principal facility. It is therefore not allowed to use some commands of the CICS application programming interface:
  • Terminal control commands that reference the principal facility
  • Options of EXEC CICS ASSIGN that return terminal attributes
  • BMS commands
  • Sign-on and sign-off commands.