OSI/FTAM Programming Guide

NonStop FTAM Programming
HP NonStop OSI/FTAM Programming Guide—528612-001
3-13
Data-Value Parameter
respectively. For descriptions of both structures, see the OSI/FTAM Programming
Reference Manual.
The contents of data-value differs depending on the FTAM document type being
transferred. The subsections on the individual document types later in this section
describe how applications handle data for the various document types.
Two other considerations are important to remember when building and processing
data-value:
•
Length of the data element and the use of pad bytes
•
Limits on the size of the data-value parameter
These topics are described in the subsections that follow.
Pad Bytes
All structures are word-addressed and must therefore begin on word boundaries. If the
length of a data element is an odd number, the data must be followed by a pad byte.
For data indications, the initiator provides pad bytes, where needed, before passing the
data-value parameter up to the application. For data requests, the application must
provide the pad bytes, if needed, before sending the data-value parameter to the
initiator. The ZLEN value of ZAPS-DDL-DATA-ELEMENT-HDR, which defines the
length of the data in the element, should not include the pad byte in the count.
The following sample program code, in the TAL programming language, illustrates how
to find the starting address of the next data element, based on the pad-byte
requirement, by processing the data-value parameter passed from an
FTM_DATA_IND_ call. The ZAPSTAL file residing in the ZOSIFTAM distribution
subvolume contains the data structure definitions needed for this procedure. The
building of the data-value parameter for an FTM_DATA_REQ_ call follows similar
principles.