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Java Binding for JSON-LD

Build Status

Java Binding for JSON-LD (JB4JSON-LD) is a simple library for serialization of Java objects into JSON-LD and vice versa.

Note that this is the core, abstract implementation. For actual usage, a binding like https://github.com/kbss-cvut/jb4jsonld-jackson has to be used.

More information can be found at https://kbss.felk.cvut.cz/web/kbss/jb4json-ld.

Usage

JB4JSON-LD is based on annotations from JOPA, which enable POJO attributes to be mapped to ontological constructs (i.e. to object, data or annotation properties) and Java classes to ontological classes.

Use @OWLDataProperty to annotate data fields and @OWLObjectProperty to annotate fields referencing other mapped entities.

See https://github.com/kbss-cvut/jopa-examples/tree/master/jsonld for an executable example of JB4JSON-LD in action (together with Spring and Jackson).

Example

Java

@OWLClass(iri = "http://onto.fel.cvut.cz/ontologies/ufo/Person")
public class User {

    @Id
    public URI uri;

    @OWLDataProperty(iri = "http://xmlns.com/foaf/0.1/firstName")
    private String firstName;

    @OWLDataProperty(iri = "http://xmlns.com/foaf/0.1/lastName")
    private String lastName;
    
    @OWLDataProperty(iri = "http://xmlns.com/foaf/0.1/accountName")
    private String username;

    @OWLDataProperty(iri = "http://krizik.felk.cvut.cz/ontologies/jb4jsonld/role")
    private Role role;  // Role is an enum

    @Properties
    private Map<String, Set<String>> properties;
    
    // Getters and setters follow
}

JSON-LD

{
  "@context": {
    "firstName": "http://xmlns.com/foaf/0.1/firstName",
    "lastName": "http://xmlns.com/foaf/0.1/lastName",
    "accountName": "http://xmlns.com/foaf/0.1/accountName",
    "isAdmin": "http://krizik.felk.cvut.cz/ontologies/jb4jsonld/isAdmin",
    "role": "http://krizik.felk.cvut.cz/ontologies/jb4jsonld/role"
  },
  "@id": "http://krizik.felk.cvut.cz/ontologies/jb4jsonld#Catherine+Halsey",
  "@type": [
    "http://onto.fel.cvut.cz/ontologies/ufo/Person",
    "http://krizik.felk.cvut.cz/ontologies/jb4jsonld/User",
    "http://onto.fel.cvut.cz/ontologies/ufo/Agent"
  ],
  "isAdmin": true,
  "accountName": "halsey@unsc.org",
  "firstName": "Catherine",
  "lastName": "Halsey",
  "role": "USER"
}

Configuration

Parameter Default value Explanation
ignoreUnknownProperties false Whether to ignore unknown properties when deserializing JSON-LD. Default behavior throws an exception.
scanPackage "" Package in which the library should look for mapped classes. The scan is important for support for polymorphism in object deserialization. It is highly recommended to specify this value, otherwise the library will attempt to load and scan all classes on the classpath.
requireId false Whether to require an identifier when serializing an object. If set to true and no identifier is found (either there is no @Id field or its value is null), an exception will be thrown. By default a blank node identifier is generated if no id is present.

See cz.cvut.kbss.jsonld.ConfigParam.

Getting JB4JSON-LD

There are two ways to get JB4JSON-LD:

  • Clone repository/download zip and build it with Maven,
  • Use a Maven dependency:
<dependency>
    <groupId>cz.cvut.kbss.jsonld</groupId>
    <artifactId>jb4jsonld</artifactId>
</dependency>

Note that you will most likely need an integration with a JSON-serialization library like JB4JSON-LD-Jackson.