OSI/FTAM Programming Guide

NonStop FTAM Programming
HP NonStop OSI/FTAM Programming Guide—528612-001
3-17
Data-Value Parameter
Where NE = number of data elements
ZLEN
i
= length in bytes of the ith character string
PAD = pad byte following string; if string length is even,
PAD = 0; otherwise, PAD = 1; for the purposes of
these calculations, PAD = 1
ND = number of node descriptors
FSL = FADU structure length (size of ZFTM-DDL-DE-FADU
data structure, or 50 bytes)
16 = maximum data-value data header overhead
26 = maximum data-value element-header overhead per data
element
Data-value limit for most transfers (excludes FTAM-2 files with
FA access context):
NE-1
∑ ZLEN
i
+ ((26 + PAD) * NE) + 16 <= 24576
i=0
Data-value limit for transfers of FTAM-2 files with FA access
context:
NS-1
∑ ZLEN
i
+ (FSL * ND)+(26 * ND) + ((26+PAD) * NE) +16 <= 24576
i=0
Encoded-Data Limits. The formulas for calculating the size of the encoded-data is the
same whether the application is sending or receiving data. These formulas apply only
to PDUs that contain primitive strings; PDUs containing constructed strings have
additional overhead. As mentioned above, the encoded data limit is 16 KB.
Two formulas are used: one for transfers of FTAM-1, FTAM-2 files with UA access
context, and FTAM-3 files, and one for transfers of FTAM-2 files with an FA access
context:
Where NS = number of character strings
ND = number of node descriptors
ZLEN
i
= length in bytes of a given character string
TAG = number of bytes used to encode the data tag
LEN = number of bytes used to encode the string length
8 = length in bytes of an encoded node descriptor
structure
Encoded-data limit for most transfers (excludes FTAM-2 files
with FA access context):