This section describes data flow from a client to a CICS® program, and
from a CICS program back to the client.
Figure 37 shows the progress of data from the client to the
CICS program during a remote procedure call.
In this example the processing is as follows:
- 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.
- The data is transmitted over the network to the host.
- In the host, the inbound XDR routine rebuilds the data as it was in the
client.
- The Decode function of the converter reorganizes
the data into a communication area for the CICS program.
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:
- Contiguous--the data to be returned to the client does not start
at the beginning of the communication area, but at some offset into it.
- Overlaid--the data to be returned starts at the beginning of the
communication area. The CICS program overwrites the inbound client data in this
area with any data to be returned to the client.
Figure 38 illustrates these two possibilities.
Figure 39 shows the progress of data from the CICS program back
to the client.
The processing is as follows:
- 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.
- The outbound XDR routine packages the data for transmission.
- The data is transmitted over the network to the client.
- In the client, the inbound XDR routine rebuilds the data as it was in
the host.
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