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diff --git a/hurd/translator/xmlfs.mdwn b/hurd/translator/xmlfs.mdwn index a4de1668..6028d43f 100644 --- a/hurd/translator/xmlfs.mdwn +++ b/hurd/translator/xmlfs.mdwn @@ -11,6 +11,80 @@ License|/fdl]]."]]"""]] `xmlfs` is a translator that provides access to XML documents through the filesystem. +# How to Use xmlfs + + xmlfs - a translator for accessing XML documents + +This is only an alpha version. It works in read only. It supports +text nodes and attributes. It doesn't do anything fancy like size +computing, though. Here is an example of how to use it: + + $ wget http://cvs.savannah.nongnu.org/viewvc/*checkout*/hurdextras/xmlfs/example.xml?content-type=text%2Fplain; + $ settrans -ca xml /hurd/xmlfs example.xml #the website says to use ./xmlfs + $ cd xml; ls + library0 library1 + $ cd library0; ls -A + .text1 .text2 @name book0 book1 book2 sub-library0 sub-library1 + $ cat .text2 + +CDATA, again ! + + $ cat book0 + <book> + <author>Mark Twain</author> + <title>La case de l'oncle Tom</title> + <isbn>4242</isbn> + </book> + $ cat book0/author/.text + Mark Twain + +As you can see, text nodes are named .textN, with N an integer +starting from 0. Sorting is supposed to be stable, so you get the same +N every time you access the same file. If there is only one text node +at this level, N is ommitted. Attributes are prefixed with @. + +An example file, example.xml, is provided. Of course, it does not +contain anything useful. xmlfs has been tested on several-megabytes +XML documents, though. + +Comments are welcome. + + -- Manuel Menal <mmenal@hurdfr.org> + +# TODO +- Handle memory usage in a clever way: + - do not dump the nodes at each read, try to guess if read() + is called in a sequence of read() operations (e.g. cat reads + 8192 bytes by 8192 bytes) and if it is, cache the node + contents. That'd need a very small ftpfs-like GC. + - perhaps we shouldn't store the node informations from + first access to end and have a pool of them. That might come + with next entries though. +- Handle changes of the backing store (XML document) while running. + (Idea: we should probably attach to the XML node and handle + read()/write() operations ourselves, with libxml primitives.) +- Write support. Making things like echo >, sed and so on work is + quite obvious. Editing is not -that- simple, 'cause we could + want to save a not XML well-formed, and libxml will just return + an error. Perhaps we should use something like 'sync'. +- Handle error cases in a more clever way ; there are many error + conditions that will just cause xmlfs to crash or do strange + things. We should review them. +- Make sorting *really* stable. + +# TODO WISHLIST +-------- + +- Kilobug suggested a --xslt option that would make xmlfs provide + a tree matching the XSLT-modified document. + (Problem: In this case we cannot attach easily to the .xml 'cause + the user would loose access to theirs original document. Perhaps + we should allow an optional "file.xml" argument and check if it + is not the same as the file we are attaching to when --xslt is + specified.) +- DTD support ; perhaps XML schema/RelaxNG when I'm sure I understand + them ;-) + # Source |