So far I have been using custom JSON api and it have been so painful that I have decided to rewrite the backend to deal with JSONAPI instead of my custom JSON. However, reading the jsonapi.org specs it seems there are a lot of things to implement but I read somewhere I don't remember that ember-data actually uses a subset of the specifications.
However I cannot find anywhere in documentation, guides and googling as to which specs actually ember data uses. I want only to implement that given my time constraint. I will appreciate if anyone help me on this
Following the discussion in comments, it appears Ember.js implements JSON API 1.0 and not just a subset of it. Here is the announcement make back when Ember 1.13 was released : http://emberjs.com/blog/2015/06/18/ember-data-1-13-released.html#toc_json-api-support
For anyone looking for implementing a JSON API compatible backend, and therefore compatible out of the box with ember-data, there is a list of implementations for a large variety of languages/frameworks here : http://jsonapi.org/implementations/