Sunday, 6 November 2011


A few days ago I asked a few guys at work that if they were given a choice, would they choose JSON or XML as a format for a REST API. Everyone responded in favor of JSON. What is surprising in this is that they were all java developers, not a single javascript guy. Maybe it is too early to say this, but it seems that after the initial success of XML in the previous decade and stagnation in the last few years, the XML as format is slowly getting to decline, while more compact and simple, schemaless formats seem to rise: JSON and YAML.
JSON and YAML implementations are just as simple as their formats, you can choose from very many of them.

Question: How do JSON parsers compare to XML parsers from performance perspective?

I wrote sample inputs in XML and JSON. The same data, basically. For XML, I have made two input files. The first is the 'traditional' XML, no attributes at all. The second uses some attributes. The third is the JSON version. I used very few XML apis, only the ones packaged into JDK, this is a bit unfair because the alternative XML apis may be a little faster than the default. I have made a test a few years age and that showed them not so much different, so I was more interested in JSON. With JSON format, I used 5 different parsers:, jackson, jsonlib, jsonj and gson.

Even the slowest JSON parser is faster than the XML parsers of JDK, also the format is more compact, looks like it is win. Jackson is much faster than the rest. It's website is right, it is very fast.

Test source code: here.