ZeroMQ

Serialization Languages

Serialization languages have their fashions. XML used to be big as in popular, then it got big as in overengineered, and then it fell into the hands of “Enterprise Information Architects” and it’s not been seen alive since. Today’s XML is the epitome of “somewhere in that mess is a small, elegant language trying to escape.”

Still, XML was way, way better than its predecessors, which included such monsters as the Standard Generalized Markup Language (SGML), which in turn were a cool breeze compared to mind-torturing beasts like EDIFACT. So, the history of serialization languages seems to be one of gradually emerging sanity, hidden by waves of revolting EIAs doing their best to hold onto their jobs.

JSON popped out of the JavaScript world as a quick-and-dirty “I’d rather resign than use XML here” way to throw data onto the wire and get it back again. JSON is just minimal XML expressed, sneakily, as JavaScript source code.

Here’s a simple example of using JSON in a Cheap protocol:

"protocol": {
    "name": "MTL",
    "version": 1
},
"virtual-host": "test-env"

The same example in XML would be (XML forces us to invent a single top-level entity):

<command>
    <protocol name = "MTL" version = "1" />
    <virtual-host>test-env</virtual-host>
</command>

And using plain-old HTTP-style headers:

Protocol: MTL/1.0
Virtual-host: test-env

These are all pretty equivalent, so as long as you don’t go overboard with validating parsers, schemas, and other “trust us, this is ...