ONC RPC concepts

This section introduces the basics of ONC RPC operation, its place in TCP/IP networks, and how its main facilities work. It does not cover all aspects of ONC RPC or TCP/IP, only those that relate to CICS® ONC RPC.

CICS ONC RPC

In the rest of this section, boxes like this point out how CICS ONC RPC implements the area of ONC RPC being described in the text.

RPC

When a process invokes or calls a process on a remote system, that call is a remote procedure call (RPC). The calling process is a client (that is, a process requesting a service); the remote process is a server (a process offering a service). As shown in Figure 30, the client sends a request for a procedure to be run, and supplies parameters for that particular run. Once the server has run the procedure, it returns the reply.

Figure 30. Basic RPC operation
 Diagram showing the flow of an RPC request as described in the preceding paragraph.

In the RPC model, there is no provision for coordinating changes to recoverable resources in different servers, nor for coordinating changes to recoverable resources in successive calls to the same server. Committing changes to recoverable resources is under the control of the remote procedure, not the client application.

Several RPC implementations have been developed and are now available on a variety of systems. RPC allows a programmer to network an application by distributing the procedures that make up the application across different processors. This is done without the programmer becoming involved with the details of the communication interface required to transmit the parameters to and from the remote procedures.

ONC

ONC is Open Network Computing, a range of software developed by Sun Microsystems. As well as the ONC RPC routines, Sun provides XDR (eXternal Data Representation) routines, which are used for data conversion. The ONC RPC and XDR protocols and formats are supported on many different platforms.

CICS ONC RPC

CICS ONC RPC allows users to run only ONC RPC servers under CICS hosts. It does not support client applications running under CICS.

TCP/IP

ONC RPC applications use the TCP/IP family of protocols. See TCP/IP protocols for more information about TCP/IP.

Related concepts
ONC RPC facilities
ONC RPC naming and routing
Related tasks
Setting up CICS ONC RPC
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