What the Run-Time Interface Does
The CA IDMS DLI Transparency run-time interface accepts database calls from a DL/I application program, issues corresponding CA IDMS/DB calls, and returns data and/or status information to the DL/I application program. Note that a single DL/I call can result in several CA IDMS/DB requests. More specifically, CA IDMS DLI Transparency processing is divided between the interface's front-end and back-end processors.
Front-End Processor
The front-end processor intercepts DL/I requests from the application program, reformats the requests, and passes them to the back-end processor. When the back-end processor finishes with a request, it passes the results (data retrieved from the database and/or status information) back to the front-end processor. It also passes back PCB status information. The front-end processor then returns the status information to the DL/I application program.
Back-End Processor
Upon receiving a DL/I request from the front-end processor, the back-end processor accesses the IPSB load module to formulate the corresponding CA IDMS/DB requests. The back-end processor then passes the request to CA IDMS/DB. When CA IDMS/DB performs the requested operation(s), the back-end processor accepts the results from CA IDMS/DB and passes them, along with the PCB status information, to the front-end processor.
Figure 3. CA IDMS DLI Transparency runtime environment
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