6.1.3 Data Conversion For DPL Services
The Oracle Tuxedo Mainframe Adapter for SNA system supports remote CICS services as Distributed Program Link (DPL) programs. The DPL support is performed as if the ATMI service is a peer CICS/ESA service.
In a DPL program, the application is protected from all Distributed Transaction Processing
(DTP). The DPL application is a request/response service, with all data communication
performed by the passing of a COMMAREA.
A basic DPL request API looks like this:
EXEC CICS LINK
PROGRAM()
DATALENGTH()
LENGTH()
COMMAREA()In the preceding example, the requester sends the COMMAREA of
DATALENGTH size and the receiving application receives the
COMMAREA data contents in a buffer the size of LENGTH. The
DATALENGTH size might be smaller than the LENGTH size, but the
requester expects and receives the response in the original COMMAREA buffer the
size of LENGTH.
The difference between a DPL program and an ATMI service is that a receiving ATMI service can resize a reply buffer, while the DPL program expects a reply buffer of a designated size. Also, an ATMI requester can receive a resized buffer in a buffer different from the original reply buffer.
The Oracle Tuxedo Mainframe Adapter for SNA software performs the manipulation described in the following subsections to smoothly adjust to the requirements of both types of applications.