Specify data compression using DCCLTDATACOMP in the client environment definition.

The data compression can be used if the service-requested TP1/Server Base is version 03-03 or later.

Using this facility, TP1/Client compresses the value of the input parameter (in) set by the dc_rpc_call_s function which is issued from the CUP and sends it to the network. For this inquiry, the value of the response (out) returned from the SPP is also compressed by TP1/Server and sent to the network. TP1/Client that receives the response decompresses the compressed data and passes it to the CUP.

The compression depends on the version of the service-requested TP1/Server Base as follows.

(a) Version 03-05 or earlier

When the input parameter value is not compressed, TP1/Server Base does not compress the response value even if compressing it will be effective.

(b) Version 03-06 or later

Even if the input parameter value is not compressed, TP1/Server Base compresses the response value if compressing it will be effective.

The following figure gives an overview of the data compression.

Figure 2-6 Overview of data compression

The effect of the data compression depends on the contents of the user data. The data compression is effective when the user data contains many consecutive identical characters. For some types of user data, it is hardly effective at all. When executing the dc_rpc_call_s function more than once from the same CUP, consider the effect of the data compression for each CUP.

Because compressing and decompressing data requires much overhead, consider the effect of the data compression and evaluate its performance before using it.