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Hurd [[translators|hurd/translator]] allow presenting underlying data in a
different format.  This is a very powerful ability: it allows using standard
tools on all kinds of data, and combining existing components in new ways, once
you have the necessary translators.

A typical example for such a translator would be xmlfs: a translator that
presents the contents of an underlying XML file in the form of a directory
tree, so it can be studied and edited with standard filesystem tools, or using
a graphical file manager, or to easily extract data from an XML file in a
script etc.

The exported directory tree should represent the DOM structure of the document,
or implement XPath/XQuery, or both, or some combination thereof (perhaps XPath/XQuery could
be implemented as a second translator working on top of the DOM one) --
whatever works well, while sticking to XML standards as much as possible.

Ideally, the translation should be reversible, so that another, complementary
translator applied on the expanded directory tree would yield the original XML
file again; and also the other way round, applying the complementary translator
on top of some directory tree and xmlfs on top of that would yield the original
directory again.  However, with the different semantics of directory trees and
XML files, it might not be possible to create such a universal mapping.  Thus
it is a desirable goal, but not a strict requirement.

The goal of this project is to create a fully usable XML translator, that
allows both reading and writing any XML file.  Implementing the complementary
translator also would be nice if time permits, but is not mandatory part of the
task.

The [[existing_partial_(read-only)_xmlfs_implementation|hurd/translator/xmlfs]]
can serve as a starting point.

This task requires pretty good designing skills.  Very good knowledge of XML is also
necessary.  Learning translator programming will obviously be necessary to
complete the task.

Possible mentors: Olaf Buddenhagen (antrik)

Exercise: Make some improvement to the existing xmlfs, or some other existing
Hurd translator. (Especially those in
[hurdextras](http://www.nongnu.org/hurdextras/) are often quite rudimental --
it shouldn't be hard to find something to improve...)