xml-dev - RE: RFC: Attributes and XML-RPC

[Mark Nutter <mnutter@fore.com>]

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"
       
twentystr="$twentystr">$word</word>
EOM
    print CHILD <<EOM;
  <word>
    <time>$time</time>
    <timestr>$timestr</timestr>
    <twenty>$twenty</twenty>
    <twentystr>$twentystr</twentystr>
  </word>
EOM
}

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

close CHILD;
close ATTRIB;
close WORDS;

-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-

Mark Nutter, <mnutter@fore.com>

Internet Applications Developer

FORE Systems

Some people are atheists 'til the day they die.