CICS ONC RPC data flow

This section describes data flow from a client to a CICS® program, and from a CICS program back to the client.

From client to CICS program

Figure 37 shows the progress of data from the client to the CICS program during a remote procedure call.

Figure 37. Data flow from client to CICS program
 This diagram shows the data flow described in the following text.

In this example the processing is as follows:

  1. The client call has a parameter which includes a pointer to data that is to be passed to the CICS program. The client’s outbound XDR routine packages the parameter and the indirect data for transmission to the host.
  2. The data is transmitted over the network to the host.
  3. In the host, the inbound XDR routine rebuilds the data as it was in the client.
  4. The Decode function of the converter reorganizes the data into a communication area for the CICS program.

Data format in the CICS program communication area

If the call is a blocking call, the position in the CICS program’s communication area of data to be returned to the client has to be specified. The data in the CICS program’s communication area can be organized in two ways:

Figure 38 illustrates these two possibilities.

Figure 38. Use of communication area according to data format
 This diagram illustrates the two possibilities described in the preceding text.

From CICS program to client

Figure 39 shows the progress of data from the CICS program back to the client.

Figure 39. Data flow from CICS program to client
 This diagram shows the steps involved in sending data back to the client, as described in the following text.

The processing is as follows:

  1. The CICS program’s output is in the communication area that was created by the Decode function. The Encode function reorganizes the data in the manner that the client expects. In this case the client is expecting to get back a structure including two pointers to indirect data. The Encode function puts the data in a single area of storage to simplify storage management processing when the area is to be freed.
  2. The outbound XDR routine packages the data for transmission.
  3. The data is transmitted over the network to the client.
  4. In the client, the inbound XDR routine rebuilds the data as it was in the host.

Related concepts
ONC RPC concepts
ONC RPC remote procedures and CICS programs
CICS ONC RPC transactions
CICS ONC RPC user-replaceable programs
CICS ONC RPC control flow
Related tasks
Setting up CICS ONC RPC
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