JSON, data and the REST
Tomorrow, on 8.8. is the International JSON day. Why? Because I say so!
Is there a better way to say ‘thank you’ to a person who gave us so much – yeah, I’m talking about Doug Crockford – and to acknowledge how handy, useful and cool the piece of technology is, this person ‘discovered‘?
From its humble beginning some 10 years ago, JSON is now the light-weight data lingua franca. From the nine Web APIs I had a look at recently in the REST: From Research to Practice book, seven offered their data in JSON. These days it is possible to access and process JSON data from virtually any programming language – check out the list at json.org if you doubt that. I guess the raise of JSON and its continuing success story is at least partially due to its inherent simplicity – all you get are key/value pairs and lists. And in 80% or more of the use cases that is likely all you need. Heck, even I prefer to consume JSON in my Web applications over any sort of XML-based data sources or any given RDF serialization.
But the story doesn’t end here. People and organisations nowadays in fact take JSON as a given basis and either try to make it ‘better’ or to leverage it for certain purposes. Let’s have a look at three of these examples …
I reckon one of the first and most obvious things people where discussing once JSON reached a certain level of popularity was how to validate JSON data. And what do we do as good engineers? We need to invent a schema language, for sure! So, there you go: json-schema.org tries to establish a schema language for JSON. The IETF Internet draft by Kris Zyp states:
JSON Schema provides a contract for what JSON data is required for a given application and how to interact with it. JSON Schema is intended to define validation, documentation, hyperlink navigation, and interaction control of JSON data.
One rather interesting bit, beside the obvious validation use case, is the support for ‘hyperlink navigation’. We’ll come back to this later.
Enter OData. Microsoft, in a very clever move adopted Atom and the APP and made it core of OData; but they didn’t stop there – Microsoft is using JSON as one of the two official formats for OData. They got this one dead right.
OData is an interesting beast, because here we find one attempt to address one of the (perceived) shortcomings of JSON – it is not very ‘webby’. I hear you saying: ‘Hu? What’s that and why does this matter?’ … well it matters to some of us RESTafarians who respect and apply HATEOAS. Put short: as JSON uses a rather restricted ‘data type’ system, there is no explicit support for URIs and (typed) links. Of course you can use JSON to represent and transport a URI (or many, FWIW). But the way you choose to represent, say, a hyperlink might look different from the way I or someone else does, meaning that there is no interoperability. I guess, as long as HATEOAS is a niche concept, not grokked by many people, this might not be such a pressing issue, however, there are cases were it is vital to be able to unambiguously deal with URIs and (typed) links. More in the next example …
Can I squeeze a graph into JSON? Sir, yes, Sir!
On a related note: initially, the W3C planned to standardize how serialize RDF in JSON. Once the respective Working Group was in place, this was dropped. I think they made a wise decision. Don’t get me wrong, I’d have also loved to get out an interoperable way to deal with RDF in JSON, and there are certainly enough ways how one could do it, but I guess we’re simply not yet there. And JSON-LD? Dunno, to be honest – I mean I like and support it and do use it, very handy, indeed. Will it be the solution for HATEOAS and Linked Data. Time will tell.
Wrapping up: JSON is an awesome piece of technology, largely due to its simplicity and universality and, we should not forget: due to a man who rightly identified its true potential and never stopped telling the world about it.
Tomorrow, on 8.8. is the International JSON day. Join in, spread the word and say thank you to Doug as well!
Filed under: Announcement, Big Data, Cloud Computing, IETF, Linked Data, NoSQL, W3C