Consider these items regarding the length of conversations
when using DDM.
Within a source job, if it is likely that a DDM conversation will be used
by more than one program or DDM file, *KEEP is the value that should be specified
for the DDMCNV job attribute. This saves the time and resources needed to
start a target job (TDDM) each time a DDM file is accessed for the same location
and mode combination within the source job.
There is significant server and communications line overhead when a target
DDM manager is started. The processing includes the APPC program start request,
server type identification, and file open processing. However, if it is not
necessary to keep the conversation active, *DROP should be specified for DDMCNV.
When the local DDM file is closed, the session being used is released for
use by other jobs using DDM or other APPC functions, such as SNADS and display
station pass-through, to the same remote server.
When the source and target servers are iSeries™ servers
or System/38™, the file input
and output requests made by an application program use a form of DDM support
that minimizes the amount of time needed to code and decode each request.
This is accomplished by System/38 extensions
to the DDM architecture.
When the source and target servers are neither
an iSeries server nor a System/38, then System/38 extensions
to the DDM architecture are not used.