This is a quick post about JSON-B specification which is due in Java EE 8. It’s main purposes are
- Provide JSON binding i.e. marshalling and un-marshalling to and from Java objects
- Eclipselink will server as Reference Implementation
- Supports Java object model to JSON mapping via annotations
- Supports default mapping for implicit transformations b/w Java model and JSON (without annotation/additional metadata)
- Produce JSON schema from Java classes
- Support further customization of default mapping mechanisms as well as partial mapping (part of JSON doc needs to be mapped to Java model)
- Will integrate with JSON-P and probably with JSON API JEP 198 (Java SE API for JSON processing) if needed
Please note that
- this is just a quick test of the JSON-B implementation in a Java EE 7 container
- not an ideal scenario i.e. it does not demonstrate integration of the JSON-B spec with a Java EE container (at least not yet)
- I am not aware of Java EE 8 builds which ship with JSON-B implementation as of now
From a (Java EE 8) container integration perspective (near future)
the integration should/will be seamless and transparent – the way it is in case of JSON-P and JAXB annotated classes i.e.
- you will ideally be able to annotate your Java classes using JSON-B annotations and
- expect them to get serialized/deserialized automatically by the container (e.g. JAX-RS runtime) automatically
Overview of what was done
- Have a simple POJO
- Expose POJO using JAX-RS (GET, POST)
- Use JAX-RS Message Body Reader and Writer – this overrides the default JSON-P providers and leverage JSON-B API here (simply use the default mapping feature) for transformation
- Repeat the same for a ‘List of’ POJOs
Github project available here – this is not a Maven project. Ideally, you would want to clone into NetBeans, build and run on a Java EE 7 container. Make sure to have RI JAR in WAR (details below)
To be noted
- I could not grab the Maven artifact of the JSON-B API JAR (maybe I am missing something), so ended up including the JSON-B API sources in the WAR itself
- Same case with the RI – Downloaded it directly from here
More than this example, what’s important is the following
- You can grab the draft specification, API sources and javadocs from here (the API sources itself are a part of the ZIP downloaded using this link)
- Please do check out this presentation from Dmitry Kornilov
- Check out the Reference Implementation here
Cheers!
