How to create a DAO/Service layer with Grizzly/JAX-RS

Question

I'm using Grizzly instead of Glassfish for this JAX-RS application. I'm new to this technology so I've been googling around a lot and can't seem to find a good outline for how to setup a Service/DAO layer in my applicatiion.

Below is the working prototype that I have.

My Resource

@Path("/helloworld")
@Stateless
public class MyResource {

    @EJB //DOESN'T WORK - how do I map this service to this resource?
    WorkflowService workflowService;

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String TestRequest() {
        Workflow workflow = new Workflow();
        workflow.setName("test");

        workflowService.save(workflow);

        return "Workflow ID:";
    }
}

My Dao

public class WorkflowDao {

    @PersistenceContext(unitName = "unit")
    private EntityManager entityManager;

    public int save(Workflow workflow) {
        entityManager.persist(workflow);
        return workflow.getId();
    }
}

My Service

@Stateless
public class WorkflowService {

    @EJB //I know EJB is probably wrong here, not sure what else to do yet.
    WorkflowDao workflowDao;

    public int save(Workflow workflow) {
        int id = workflowDao.save(workflow);
        return id;
    }
}

Update - I realize EJB won't work with my setup. So my question is, what does? How do I make the service accessible in my resource?

-------------- Final/Working Code --------------

Resource

@Path("/helloworld")
public class MyResource {

    WorkflowService workflowService;

    public MyResource() {
        workflowService = new WorkflowService();
    }

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String TestRequest() {
        Workflow workflow = new Workflow();
        workflow.setName("test");

        workflowService.save(workflow);

        return "Workflow ID:";
    }
}

Service

public class WorkflowService {

    WorkflowDao workflowDao;

    public WorkflowService() {
        workflowDao = new WorkflowDao();
    }

    public int save(Workflow workflow) {
        int id = workflowDao.save(workflow);
        return id;
    }
}

DAO

@Singleton
public class WorkflowDao {

    private EntityManager entityManager;

    public int save(Workflow workflow) {
        getEntityManager().persist(workflow);
        return workflow.getId();
    }

    protected EntityManager getEntityManager() {
        EntityManagerFactory emf = Persistence.createEntityManagerFactory("unit");
        EntityManager em = emf.createEntityManager();
        return em;
    }
}

score 1 · Accepted Answer · answered Feb 14 '13 at 14:59

1

I'm not sure I can answer your question fully. But I can tell you that @EJBis part of JavaEE 6 which can only be run in a WebApplication Server.

Grizzly is not one of them (compared to Glassfish which is one).

EDIT

If you want to have dependency injection you can use the Spring framework.

answered Feb 14 '13 at 14:59

To answer your updated question, I've added Spring in my previous answer. Also, you can choose to instantiate your services in your JAXRS implementation, and make your DAO a singleton. – Feb 14 '13 at 15:08
When they're instantiated in my JAXRS implement can you provide a code example? For instance, I know I can do `workflowservice = new WorkflowService();`, but how will I map the `EntityManager` to the DAO? I'll add `@Singleton` to my DAO – Ben Feb 14 '13 at 15:13
You can just use the singleton pattern to make your DAO a singleton ;) see http://en.wikipedia.org/wiki/Singleton_pattern#Eager_initialization – Feb 14 '13 at 15:16
Can you provide any insight on how I should map the `EntityManager`? – Ben Feb 14 '13 at 15:41
1

You can use an `EntityManagerFactory`, although I cannot remember the exact syntax for using it. – Feb 14 '13 at 15:44

How to create a DAO/Service layer with Grizzly/JAX-RS

1 Answers1