RFC: Attributes and XML-RPC

Andrew Layman andrewl at microsoft.com
Fri Sep 24 23:08:53 BST 1999

These results are consistent with tests that I have run against actual XML
files generated from databases.  After compression, there is little
difference between different syntactic families.

-----Original Message-----
From: Mark Nutter [mailto:mnutter at fore.com]
Sent: Wednesday, September 22, 1999 10:26 AM
To: xml-dev at ic.ac.uk
Subject: RE: RFC: Attributes and XML-RPC

At 12:16 PM 09/22/99 -0400, Hunter, David wrote:

So even if you
compress the files, the attribute version will be able to compress to 50%
smaller than the other file.  Again, 2KB isn't a lot, but if we're talking
megabytes in size, 50% is a lot.

I wrote a quick perl script to take /usr/dict/words and turn it into an XML
file, with some artificially generated "attributes".  In the resulting file
named attrib.xml, each <word> tag contains the additional information as
attributes.  I did the same thing to produce a file called child.xml, except
that the additional information is presented as a child element instead of
as an attribute.  Here are the results:

$ ./make.pl
$ ls -l
total 13004
-rw-rw-r--   1 mnutter  mnutter   5811852 Sep 22 13:16 attrib.xml
-rw-rw-r--   1 mnutter  mnutter   7445892 Sep 22 13:16 child.xml
-rwxr-xr-x   1 mnutter  mnutter       976 Sep 22 13:16 make.pl
$ gzip attrib.xml
$ gzip child.xml
$ ls -l
total 1127
-rw-rw-r--   1 mnutter  mnutter    671039 Sep 22 13:16 attrib.xml.gz
-rw-rw-r--   1 mnutter  mnutter    472394 Sep 22 13:16 child.xml.gz
-rwxr-xr-x   1 mnutter  mnutter       976 Sep 22 13:16 make.pl

I used gzip as an example of off-the-shelf compression technology.  As you
can see, even though the raw child.xml file is larger, the compressed
version is *smaller* than the corresponding implementation with attributes.

This may not be true in all cases, of course, but I expect it often will,
due to the way such compression algorithms work.

For your reference, here is the Perl script I used to create the two files:

open WORDS, "</usr/dict/words" or die "Couldn't open dictionary.\n";
open ATTRIB, ">attrib.xml" or die "Couldn't open attrib.xml\n";
open CHILD, ">child.xml" or die "Couldn't open child.xml\n";

@twenty_strings = qw(one two three four five six seven eight nine ten
                     eleven twelve thirteen fourteen fifteen sixteen
                     seventeen eighteen nineteen twenty);

print ATTRIB "<attrib>\n";
print CHILD "<child>\n";

while($word = <WORDS>)
    $time = time();
    $timestr = localtime($time);
    $twenty = rand % 20;
    $twentystr = $twenty_strings[$twenty];
    print ATTRIB <<EOM;
  <word time="$time" timestr="$timestr" twenty="$twenty"
    print CHILD <<EOM;

print ATTRIB "</attrib>\n";
print CHILD "</child>\n";

close CHILD;
close ATTRIB;
close WORDS;


Mark Nutter, <mnutter at fore.com>
Internet Applications Developer
FORE Systems
Some people are atheists 'til the day they die.

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