HP 3000 Manuals

Using NS3000/XL Network Services

File Copying Formats 

NFT uses two file copying formats:  Transparent Format and Interchange
Format.

Transparent Format 

When files are copied from a source file node that is the same type of
computer as the target file node (for example, if they are both HP 3000s
or HP 9000s), the files are copied using a format called Transparent
Format.  Transparent Format does not alter a file's attributes, but
simply copies the file.  It should be used when you want a low-overhead,
maximum-speed file copy process between systems of the same type.

Interchange Format.  When two computers are of different types (for
example, one is an HP 9000 and one is an HP 3000), files copied from one
to the other must be converted to Interchange Format (Figure 5-2).
Interchange Format consists of a set of attributes that describe a file
in a standard way so that it can be understood by any NS system.
Interchange Format is invoked by default whenever you use NFT to copy a
file residing on one type of system to a system of another type.  You can
also use a  DSCOPY command option (INT) to explicitly specify that a file
be converted to Interchange Format.  In addition, several options
automatically invoke Interchange Format.  These options are described in
the DSCOPY syntax description later in this chapter.  When a file is
copied using Interchange Format, it is translated into Interchange Format
at the source system before it is copied to the target system.  At the
target system, it is mapped from Interchange Format into the target
system's file format.  Interchange Format's standard file attributes
enable the target computer to map the source file into a target file with
attributes that match the source file's as closely as possible.


          Figure 5-2.  Interchange Format 

You can use the options that invoke Interchange Format to give a target
file a different set of attributes from those that characterized the
source file from which it was copied, even if the files are being
transferred between computer systems of the same type.  For example, by
copying a file composed of variable length records and using the  FIX
option, you can create a file containing the same information, but
formatted into fixed-length records.  Other options (described in detail
later in this chapter) can be used to create duplicate files that differ
from their source files in record size, length, type of data and other
file characteristics.  For details about copying files from one type of
computer system on a LAN to another type of system on the same LAN, refer
to theNS Cross-System NFT Reference Manual. 

Data Interpretation.  Although the purpose of Interchange Format is to
create an accessible target file on different kinds of systems, it does
not ensure that the target file will be usable.  This is because
Interchange Format changes a file's attributes only; it does not perform
data interpretation.  Interchange Format can create an unusable target
file if the target system has a different representation for the data
present in the source file.

For example, if a file that contains floating point numbers is copied to
a different kind of computer, there is no guarantee that the target node
will be able to read the data as floating point.  Consequently, the
usability of your target files must be determined by the applications
that use them.

MPE/iX 5.0 Documentation