Data files in general, and XML files in particular, can be generally be
used in three different ways:
All three approaches are supported with the XML-Fortran library. They
will be elaborated on below.
Reading XML files from top to bottom
The XML parser module is based on the concept of SAX, but it
works by letting the program read the XML file piece by piece,
instead of via call-back routines. In fact it is very much like the way
you would use READ statements to read the file:
call xml_open( info, .... )
! Get the next tag and the associated data
call xml_get( info, .... )
! Check if we have reached the end of the file or not
if ( .not. xml_ok(info) ) exit
! Handle the attributes and data for this tag
! End of file
call xml_close( info )
Storing XML files in a hierarchical data structure
Via the tree module you can load the contents of the
XML file into a tree structure and use that to query the data later on.
To be expanded ...
Generating reader routines
A completely different approach is to use a description of the variables
you want to read in via an XML file, to actually generate the code to do
so. This is the purpose of the xmlreader program, which is
currently (september 2005) under development. The idea is that in many
cases you need to load all the data contained in the XML file and then
use them in the program, in other words, the data you expect are a fixed
collection. Hence, the code to read the data from the file can be
generated automatically, provided you describe it accurately.