Re: "Binary XML" proposals

[Murali Mani <mani@CS.UCLA.EDU>]

I am aware of a few research projects that used a binary representation of
XML. I think the main things with binary XML are compressed data exchange
and storage and I think they reported faster processing than ordinary DOM.
I shall list the 3 that I have heard of. The last I heard of them was
almost a year ago.

1. PDOM - Persistent DOM - They do not do any extra compression other than
the compression due to binarization. The main point here is the DOM is not
fully memory resident - it does partial loading.
2. Millau - They separate structure and content and do compression. Mainly
it is for exchange, and I think they also got to a very primitive DOM
support. This was in WWW9, and was a research project at IBM.
3. XMill - This is from AT & T and University of Pennsylvania. I think
this achieved the most compression. Idea was similar to Millau's but in
addition, for values they used something called "column-based compression"
-- I think compression and decompression overhead as well as header
overhead is larger here.

I also think the space and time savings by the different projects were
something like:
Millau - claimed storage decreased 5 times. also claimed something like
20% savings in processing the DOM. (recollections).
XMill - claimed storage decreased only for large documents - documents
should be at least 64 kB (recollections).
But I am sure Millau claimed storage and processing got better.

regards - murali.

On Tue, 10 Apr 2001, Al Snell wrote:

> On Tue, 10 Apr 2001, Tim Bray wrote:
>
> > So, Sean may have used strong language, but in point of fact
> > he was correct, so it's forgivable.  Get some data on how
> > much space and time a binary representation will save, then
> > you'll be able to make intelligent quantitative decisions
> > on where it's worthwhile deploying it.