[BitTorrent] XML Torrents?

Konstantin 'Kosta' Welke kosta at fillibach.de
Fri Mar 11 15:29:45 EST 2005


On Fri, 11 Mar 2005 10:00:12 -0800, Kenneth Porter <shiva at sewingwitch.com> wrote:

> Yeah, I don't see the point of saving 20 bytes when we're dealing with a
> protocol designed to transfer hundreds of megabytes.
> Penny-wise/pound-foolish. For larger XML files, the "bloat" can easily be
> dealt with using commonplace compression like deflate. For example,
> OpenOffice documents are stored in zipped XML collections. Much of the
> bloat is caused by the large in-line descriptive tags, and those are
> natural candidates for leveraging dictionary-based compression.

Yeah, beencoding is hard to read for humans. But a gzip'ed XML is better?
Okay, you can unzip it to look at it, but that doesnt really seem elegant
to me... Writing an efficient, complete XML parser isnt done in 5 minutes. Okay,
many languages already have one and an XML-Torrent will be a really easy
kind of document, so you can just code one in a few lines.

 From a coders point of view, it adds complexity without real advantages,
(you need an XML parser, a base64 decoder and gzip). If you can use
gzip to look at some XML, you can also use some existing graphical
torrent file viewer or use some tool that converts it into a simple
textfile that will be much much easier to read than stupid XML.

Also, the torrents are already too big, they should be an url like http or ed2k
do it. That why there are efforts to eminate them in bt2.

> To me, the advantages of XML are extensibility,

There is nothing we need that cant be done with bencoding.

> self-documentation,

Hmm, from a programs point of view, its the same with bencoding.

> and easy validation.

bencoding is easier to validate.

> Plus the wide availability of tools to manipulate the
> format.

What do you want to manipulate that cant be done with bittorrent
tools?

> This makes it easy to implement the tracker part of new clients in
> any language that has an XML parser, and makes it easy to extend the
> protocol.

The protocol is already very easy to extend, as you can see by the
numberous extensions floating around :)

> Since the tracker acts as a web server, and XML has web origins,
> it also makes it natural to adapt existing web machinery to do the job.

Sorry, this is not a rational point.

> Is bencoding so special? If the original BT protocol had been written in
> Perl, would everyone be raving about Data::Dumper format? (And I recall
> that PHP has its own data structure dump format.)

bencoding is not some "binary dump" format. You can think of it as "XML without
the bloat", i.e. Easy to parse, space-efficient, easy to extend, but harder to
read for the human eye.

> (BTW, note that I'm not proposing XML for the peer protocol, which is much
> more performance-sensitive. For now I'm just talking about the metadata
> file (ie. the .torrent).)

That's good because it would just be completely braindead. But XML for
.torrent files can be discussed. I just dont think it would make sense.

Kosta


 
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