Apache TomEE

Example

This example depicts a similar scenario to cdi-application-scope. A restaurant guest orders a soup from the waiter. The order is passed to the chef who prepares it and passes it back the waiter who in turn delivers it to the guest.

Waiter

The Waiter session bean receives a request from the test class via the orderSoup() method. A Soup insance will be created in this method and will be shared throughout the request with the Chef bean. The method passes the request to the Chef bean. It then returns the name of the soup to the test class.

@Stateless
public class Waiter {

    @Inject
    private Soup soup;

    @EJB
    private Chef chef;

    public String orderSoup(String name){
        soup.setName(name);
        return chef.prepareSoup().getName();
    }
}

Soup

The Soup class is an injectable POJO, defined as @RequestScoped. This means that an instance will be created only once for every request and will be shared by all the beans injecting it.

@RequestScoped
public class Soup {

    private String name = "Soup of the day";

    @PostConstruct
    public void afterCreate() {
        System.out.println("Soup created");
    }

    public String getName() {
        return name;
    }

    public void setName(String name){
        this.name = name;
    }
}

Chef

The Chef class is a simple session bean with an injected Soup field. Normally, the soup parameter would be passed as a prepareSoup() argument, but for the need of this example it’s passed by the request context.

@Stateless
public class Chef {

    @Inject
    private Soup soup;

    public Soup prepareSoup() {
        return soup;
    }
}

Test Case

This is the entry class for this example.

public class RestaurantTest {

    private static String TOMATO_SOUP = "Tomato Soup";
    private EJBContainer container;

    @EJB
    private Waiter joe;

    @Before
    public void startContainer() throws Exception {
        container = EJBContainer.createEJBContainer();
        container.getContext().bind("inject", this);
    }

    @Test
    public void orderSoup(){
        String soup = joe.orderSoup(TOMATO_SOUP);
        assertEquals(TOMATO_SOUP, soup);
        soup = joe.orderSoup(POTATO_SOUP);
        assertEquals(POTATO_SOUP, soup);
    }

    @After
    public void closeContainer() throws Exception {
        container.close();
    }
}

Running

The test calls orderSoup() twice, once with "Tomato Soup" and once with "Potato Soup". In both calls the Chef gets the soup the Waiter named, because both beans share the same Soup instance while the call is running.

Both calls come from the test thread, which is not an HTTP request. For such local EJB calls the container keeps one request context for the thread, so the Soup bean is created only once and the output shows a single Soup created. In a web application, each HTTP request gets its own request context and therefore its own Soup instance.

[INFO] Running org.superbiz.cdi.requestscope.RestaurantTest
...
INFO: Deployed Application(path=.../examples/cdi-request-scope)
Soup created
INFO: Undeploying app: .../examples/cdi-request-scope
...
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0