OSI/FTAM Programming Guide

ISO FTAM Concepts
HP NonStop OSI/FTAM Programming Guide—528612-001
2-30
FTAM-2 Documents
child node that has no subsequent child node is considered a leaf node. None of the
nodes has a node name. Each data unit consists of zero, one, or more character
strings.
Your application can access the whole file through the FADU associated with the root
node (FADU identity of begin). FADUs associated with child nodes can be used to
access parts of the file.
Your application can perform only these actions on FTAM-2 files: locate, read, insert,
and erase. Existing FADUs cannot be replaced or extended. Only the root node, using
a FADU identity of begin, can be erased, causing the contents of the file to be erased.
New nodes can be inserted only at the end of a file, using a FADU identity of end. A
new node follows all existing nodes in the file. The FADU identity following the inserted
node is end.
FTAM-2 allows the use of several FADU identities depending on the file-access action.
Table 2-9 shows the valid FADU identity values for an FTAM-2 file.
Two access-context values are allowed: flat all-data units (FA) and unstructured alldata
units (UA). In the UA access context, only file-contents data elements are transferred.
No structuring data elements are transferred. Some semantics of the file—the division
Figure 2-8. Hierarchical Structure of FTAM-2 File
Table 2-9. FADU Identity Values for FTAM-2 File-Access Actions
Action Begin End First Last Current Next Previous Traversal
Locate X X X X X X X X
ReadX XXX XX X
Insert X
Erase X
Note. The read and erase actions with FADU identity of begin act upon the whole file. The
locate and insert actions act only on leaf nodes.
VST0208.vsd
Root
A
DU
B
DU
C
DU
D
DU
X
DU
Level 0
Level 1
. . .