The fls accessor generates an XML fragment
containing a directory listing of the host operating system's filesystem.
The listing is generated as the accessor walks the filesystem starting at a
specified root location.
While processing the request, resources that match a regular expression filter
are added to the listing.
The resulting document is hierarchical tree representation of the real filesystem tree.
The structure of the returned document is as follows
<fls>
...
<dir>home
<res>mydoc.doc
<uri>file:///home/mydoc.doc</uri>
</res>
</dir>
...
</fls>