Compaq OSI/FTAM D43 - Manual (Page 47)

Compaq FTAM Responder Support of
ISO FTAM Functions
OSI/FTAM Responder Manual— 425199-001
4- 11
File-Attribute Mappings
strings may require you to increase the value of the maximum-string-length parameter in
your requests. The following formula defines the conditions under which decoded data
will fit into the buffer:
NS-1
Σ
((ZLEN) i )+ ((26 + PAD) * NS) <= 25600 bytes
i=0
where
NS = number of character strings
ZLEN = length in bytes of a given character string
PAD = pad byte following string; if string length is even,
PAD = 0; otherwise, PAD = 1
26 = maximum data-header overhead per character string
When the responder retrieves data from the VFS in response to a read request, it
automatically packages it into PDUs small enough to fit into its buffer. Therefore, no
similar adjustments are necessary on read requests.
The formula for calculating the size of the encoded data is given below. This formula
applies only to PDUs that contain primitive strings; PDUs containing constructed strings
have additional overhead. As mentioned above, the encoded data limit is 16 KB.
NE-1
SIGMA((ZLEN)
i )+ ((TAG + LEN) * NS) <= 16384 bytes (16 KB)
i=0
where
NS = number of character strings
ZLEN = 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 length of string
File-Attribute Mappings
The following subsection maps FTAM virtual filestore file attributes to specific
Guardian and NonStop SQL file attributes. File attributes provide information for
various aspects of a file, such as file name, file size, date and time of file creation, and
so on.
Kernel Group File Attributes
Every FTAM implementation must fully support kernel file attributes. The kernel group
includes the filename, permitted-actions, and contents-type attributes.
Note. When the Compaq responder encodes data, the maximum encoded-data header
overhead (TAG + LEN) is always 4 bytes per string. (The same is true for data encoded by the
Compaq initiator.) An FTAM configurable file cannot be opened by the responder.