halite

A Java implementation of the Hypertext Application Language for XML and JSon. Halite allows to extend a basic model formed by a Resource and a Link object using XSD Schemas or JAXB and operate on this model to add links or embedd resources. The model object can easily be transformed to xml+hal or json+hal.

Examples

Create a resource

Resource resource = HAL.newResource("example");

The resource has an URI "example" and a link of relation (rel) "self" pointing to that URI. To extend that link, call:

resource.getLink(HAL.SELF).title("Link to self");

Create a link to other URIs

Resource res = ...; 
HAL.newLink(res, HAL.NEXT, "http://...").title("Next Page");
//or
res.addLink(HAL.NEXT, "http://...").title("Next Page");

This will create a link on resource 'res' pointing to the next page.

Adding a link to many Resources

Assume you have a set of resources and want to add the same link to each of them

Resource r1 = ...;
Resource r2 = ...;
Resource r3 = ...;
HAL.newLink("home", "http://...").title("Home").addTo(r1, r2, r3);

Embedding Resources

If you have a resource and instead of linking it to another Resource, you want to embedd the resource.

Resource parent = ...;
Resource child = ...;
parent.embed("child", child);

This will embed the child resource under the relation "child".

Writing to JSon

For writing the structure to an OutputStream the JsonHalWriter can be used. The writer writes correct _embedded and _link fields to the Json.

Resource res = ...;
OutputStream os = ...;
JsonHalWriter writer = new JsonHalWriter(os);
writer.write(res);

A better integration into Jackson Json Processor is planned.

Writing to XML

Writing to XML kind of inherently supported by JAXB as the base classes Resource and Link are JAXB annotated. So to create an XML Representation of your structure, call for instance:

Resource resource = ...;
OutputStream os = ...;
javax.xml.bind.JAXB.marshall(resource, os);

Have a look at the JAXBTest for a running example.

ChangeLog

• HAL-5 Add Jax-RS support
• HAL-4 Add (extensible) HTML support

Outlook

Support for JCR-HAL mapping