Receiving data using HPDT
This section explains how applications can be written
to receive data using the HPDT interface. Applications request an
HPDT receive by issuing the APPCCMD CONTROL=RECEIVE macroinstruction
specifying OPTCD=XBUFLST and freeing the buffers after processing
the data. The following APPCCMD macroinstructions can be used to receive
data using the HPDT interface:
- APPCCMD CONTROL=RECEIVE,QUALIFY=SPEC|ISPEC
- APPCCMD CONTROL=RECEIVE,QUALIFY=ANY|IANY
Applications using the HPDT interface to receive data
are also responsible for performing the following actions:
- Informing VTAM® of the application's
intent to use the HPDT interface.
See How support for HPDT is communicated between the application and VTAM for more information.
- Specifying storage type to be used for inbound data on the XBUFLST-receive vector.
- Specifying receive completion criteria and amount of data to be received.
When XBUFLST is specified on a receive request, the application provides a storage area pointed to by the AREA input parameter. The length of the area is specified by the AREALEN parameter. VTAM builds the receive buffer list in this storage area. The buffer list points to addresses of data that reside in CSM buffers. The RECLEN value in the RPL that is returned after the APPCCMD completes indicates the length of this buffer list that VTAM builds. The data in each CSM buffer received is described in each buffer list entry. The length of the data received is the sum of the data in all buffer list entries.