Revision as of 09:16, 15 February 2012

Lyo OSLC4J

What is OSLC4J

OSLC4J is a Java toolkit for building Open Services for Lifecycle Collaboration providers and consumers. It includes:

• annotations to decorate Java objects with OSLC attributes
• annotations to assist with resource preview UIs (compact rendering)
• built-in support for service provider and resource shape documents
• libraries to simplify service provider and consumer development
• sample applications, including an OSLC Registry (catalog) application and a Change Management provider implementation
• Tests for the sample applications to complement the [Lyo/LyoTestSuite Lyo OSLC Test Suite]

Components

• OSLC4J - The core component providing OSLC annotation and model support
• Apache Jena Provider - A library to assist with serialization/de-serialization of OSLC-annotated Java objects to/from RDF XML.
• Apache Wink Json4J Provider - A library to assist with serialization/de-serialization of OSLC-annotated Java objects to/from JSON.
• Apache Wink JAX-RS Provider - Utility classes, including an OSLC REST Client, to facilitate development using the Apache Wink JAX-RS implementation.

The Apache Jena and Apache Wink components are the built-in providers for RDF, RDF XML, JSON and JAX-RS. Additional providers could be implemented using technologies such as OpenRDF and Jersey.

Sample code

Annotation sample

<verbatim>

   //sample simple string attribute (dcterms:description)

   @OslcDescription("Descriptive text (reference: Dublin Core) about resource represented as rich text in XHTML content.")
   @OslcPropertyDefinition(OslcConstants.DCTERMS_NAMESPACE + "description")
   @OslcTitle("Description")
   @OslcValueType(ValueType.XMLLiteral)
   public String getDescription()
   {
       return description;
   }  

   //sample relationship attribute (oslc_cm:affectsTestResult)

   @OslcDescription("Associated QM resource that is affected by this Change Request.")
   @OslcName("affectsTestResult")
   @OslcPropertyDefinition(Constants.CHANGE_MANAGEMENT_NAMESPACE + "affectsTestResult")
   @OslcRange(Constants.TYPE_TEST_RESULT)
   @OslcReadOnly(false)
   @OslcTitle("Affects Test Results")
   public URI[] getAffectsTestResults()
   {
       return affectsTestResults.toArray(new URI[affectsTestResults.size()]);
   }

</verbatim>

JAX-RS method sample

<verbatim>

   //support GET for a specific OSLC ChangeRequest

   @GET
   @Path("{changeRequestId}")
   @Produces({OslcMediaType.APPLICATION_RDF_XML, OslcMediaType.APPLICATION_XML, OslcMediaType.APPLICATION_JSON})
   public ChangeRequest getChangeRequest(@Context                      final HttpServletResponse httpServletResponse,
                                         @PathParam("changeRequestId") final String              changeRequestId)
   {
       final ChangeRequest changeRequest = Persistence.getChangeRequest(changeRequestId);

       if (changeRequest != null)
       {
           changeRequest.setServiceProvider(ServiceProviderSingleton.getServiceProviderURI());

           setETagHeader(getETagFromChangeRequest(changeRequest), httpServletResponse);

           return changeRequest;
       }

       throw new WebApplicationException(Status.NOT_FOUND);
   }

   //support POST to create a new ChangeRequest

   @POST
   @Consumes({OslcMediaType.APPLICATION_RDF_XML, OslcMediaType.APPLICATION_XML, OslcMediaType.APPLICATION_JSON})
   @Produces({OslcMediaType.APPLICATION_RDF_XML, OslcMediaType.APPLICATION_XML, OslcMediaType.APPLICATION_JSON})
   public Response addChangeRequest(@Context final HttpServletRequest  httpServletRequest,
   		                         @Context final HttpServletResponse httpServletResponse,
                                             final ChangeRequest       changeRequest)
          throws URISyntaxException
   {
       final long identifier = Persistence.getNextIdentifier();

       final URI about = new URI(httpServletRequest.getScheme(),
                                 null,
                                 httpServletRequest.getServerName(),
                                 httpServletRequest.getServerPort(),
                                 httpServletRequest.getContextPath() + "/changeRequests/" + identifier,
                                 null,
                                 null);

       changeRequest.setAbout(about);
       changeRequest.setIdentifier(String.valueOf(identifier));
       changeRequest.setServiceProvider(ServiceProviderSingleton.getServiceProviderURI());

       final Date date = new Date();

       changeRequest.setCreated(date);
       changeRequest.setModified(date);

       Persistence.addChangeRequest(changeRequest);
       setETagHeader(getETagFromChangeRequest(changeRequest), httpServletResponse);

       return Response.created(about).entity(changeRequest).build();
   }

</verbatim>

Getting started with OSLC4J

• The Lyo OSLC4J project is currently provided as source code. We're working on getting jars built by the Eclipse build infrastructure
• See [Lyo/BuildingOSLC4J Setting up OSLC4J] for information on setting up a development environment.