It is a very simple and limited DOM XML parser that can work only with valid, well-formed and "good" XML.
There are more than hundred ways to crush it down with a proper XML, but it was written for a "good" XML to parse feeds and machine-generated content.
It is fast enough, convenient and has very low memory footprint due to binary usage. Really!
Usage:
{Tag, Attrs, Content} = exomler:decode(XML).
Where Tag is binary name of root tag, Attrs is a {Key,Value} list of attrs and Content is list of inner tags or Text which is binary.
XML = <<"<html key=\"value\">Body</html>">>.
{<<"html">>, [{<<"key">>, <<"value">>}], [<<Body>>]} = exomler:decode(XML).
XML = exomler:encode({<<"html">>, [{<<"key">>, <<"value">>}], [<<Body>>]}).
Download some XML and run bench:
$ ./bench.erl m.xml 500
xmerl: 8511ms 2845KB 1MB/s
exomler: 1047ms 86KB 14MB/s
erlsom: 3428ms 1759KB 4MB/s
$ wc -l m.xml
82 m.xml
$ du -hs m.xml
32K m.xml
Here we can see that small 32K file is parsed 500 times on a high speed with low memory usage. Memory usage is collected via process_info(Pid,memory)
Let's check on something bigger:
$ du -hs FIX50SP2.xml
512K FIX50SP2.xml
$ wc -l FIX50SP2.xml
10540 FIX50SP2.xml
$ ./bench.erl FIX50SP2.xml 5
xmerl: 2179ms 46622KB 1MB/s
exomler: 701ms 7449KB 3MB/s
erlsom: 854ms 18917KB 3MB/s
Here we can see, that erlsom runs on the same speed but with higher memory usage.
Lets now parse this file 100 times:
$ ./bench.erl FIX50SP2.xml 100
xmerl: 46240ms 56653KB 1MB/s
exomler: 15607ms 6501KB 3MB/s
erlsom: 17838ms 15630KB 2MB/s
exomler and erlsom take similar time, but erlsom is using more memory.
Now lets start parsing with spawn_opt([{fullsweep_after,5}]):
$ ./bench.erl m.xml 500
xmerl: 13022ms 1535KB 1MB/s
exomler: 1081ms 171KB 14MB/s
erlsom: 5045ms 1087KB 3MB/s
$ ./bench.erl ../trader/apps/fix/spec/FIX50SP2.xml 100
xmerl: 76785ms 29696KB 0MB/s
exomler: 19656ms 7449KB 2MB/s
erlsom: 23631ms 17165KB 2MB/s
Time is lowered to to frequent garbage collection, but memory footprint is again better for exomler