Oracle 1Z0-895 Online Practice Questions and Exam Preparation

Oracle 1Z0-895 Online Questions & Answers

• Question 1:

  A developer writes an interceptor class containing an AroundInvoke method, and applies it to the local business interface method of a stateless session bean:

  11.

  @Interceptors(FooInterceptor.class)

  12.

  public void bar() ()

  A client obtains a reference to the bean's local business interface, and calls the method bar two times from the same thread. Assuming that the container dispatches both cell to the same stateless session bean instance, how many instances

  of the FooInterceptor class will be used?

  B. 2
  C. 1
  D. Either 1 or 2
  B. 2

  ---

  You can specify one nonbusiness method as the interceptor method for a stateless or stateful session bean. Each time a client invokes a session bean business method, OC4J intercepts the invocation and invokes the interceptor method. Reference: Configuring an Around Invoke Interceptor Method on an EJB 3.0 Session Bean

• Question 2:

  An ejb-jar also contains three interceptor classes: AInt, BInt, CInt. Each interceptor class defines an AroundInvoke method called intercept.

  The ejb-jar also contains a stateless session bean FooBean with a local business interface Foo that declares a method foo ():

  10.

  @Stateless

  11.

  @Intercaptors ({CInt.class, BInt.class})

  12.

  public class FooBean implements Foo {

  13.

  14.

  public void foo () {}

  15.

  16.

  }

  The ejb-jar contains a META-INF/ejb-jar.xml file with an section:

  FooBean

  com.acme.AInt

  What is the interceptor order when the business methodfoo() is invoked?

  A. AInt
  B. AInt, CInt, BInt
  C. CInt, BInt, AInt
  D. AInt, BInt, CInt
  B. AInt, CInt, BInt

  ---

  With the interceptor-order clauses Aint will be first in the order of interceptors. Within each group (default, class, method) the order of the interceptors are from left to right as defined in the @Interceptors annotation, and then the xml interceptors. In this scenario, with the @Intercaptors ({CInt.class, BInt.class}) line, the ordering continues with CInt and BInt. Note 1: By default the ordering of interceptors when invoking a method are

  * External interceptors ** Default interceptors, if present ** Class interceptors, if present ** Method interceptors, if present Bean class interceptor method *

  Note 2: You can override the default sort order of the external interceptors by specifiying an interceptor- binding with an interceptor-order specifying the order of the interceptors

  Reference: EJB Interceptors

  http://docs.jboss.org/ejb3/app-server/tutorial/interceptor/interceptor.html

• Question 3:

  Which three methods can Bean Developer use in any EJB compliant container implementing the full Java EE6 product? (Choose three.)

  A. Class.getClassLoader
  B. FileInputStream.read
  C. DataSource.getConnection
  D. EJBContext.getCallerPrincipal
  E. Executors.newSingleThreadExecutor
  F. QueueConnection.createQueueSession
  B. FileInputStream.read
  C. DataSource.getConnection
  D. EJBContext.getCallerPrincipal

  ---

  D: Use EJBContext. getCallerPrincipal() to obtain the java.security.Principal that identifies the caller.

  Incorrect:

  A: Do not load native libraries.

  E: Not allowed: Starting, stopping, or managing threads in any way. That restriction eliminates the possibility of conflicts with the EJB container's responsibilities of managing locking, threading, and concurrency issues.

  Reference: Programming restrictions on EJB Reference: javax.ejb Interface EJBContext

• Question 4:

  You are writing a client that sends a message to a JMS queue. Which statement is true?

  A. You use a connection factory to create a session.
  B. When you create a session, you specify whether or not it is transacted.
  C. When you create a connection, you specify the acknowledgment mode.
  D. When you create a message producer, you must specify the name of the destination to which you will send messages.
  A. You use a connection factory to create a session.

  ---

  Note:

  The SimpleMessageClient sends messages to the queue that the SimpleMessageBean listens to. The client starts by injecting the connection factory and queue resources:

  @Resource(mappedName="jms/ConnectionFactory")

  private static ConnectionFactory connectionFactory;

  @Resource(mappedName="jms/Queue")

  private static Queue queue;

  Next, the client creates the connection, session, and message producer:

  connection = connectionFactory.createConnection();

  session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); messageProducer = session.createProducer(queue);

  Finally, the client sends several messages to the queue:

  message = session.createTextMessage();

  for (int i = 0; i < NUM_MSGS; i++) {

  message.setText("This is message " + (i + 1));

  System.out.println("Sending message: " + message.getText()); messageProducer.send(message);

  }

• Question 5:

  Given the following stateless session bean implementation classes:

  

  Assuming no other transaction-related metadata, what are the transaction attributes of methodA, methodB, and methodC respectively?

  A. MANDATORY, MANDATORY , and MANDATORY
  B. REQUIRED, MANDATORY, and REQUIRES_NEW
  C. MANDATORY, MANDATORY , and REQUIRES_NEW
  D. REQUIRED, REQUIRES_NEW, and REQUIRES_NEW
  C. MANDATORY, MANDATORY , and REQUIRES_NEW

  ---

  Note:

  *

  You can only bring out the effects of transaction attributes only when you call the method through a session bean instance and NOT through a direct method call. Even if your methods are within the same bean, you need to get the local

  instance of the same bean and call through its local interface instead of a direct method invoke.

  *

  The enum TransactionAttributeType is used with the TransactionAttribute annotation to specify whether the methods of a session bean or message driven bean are called with a valid transaction context.

  *

  MANDATORY

  If a client invokes the enterprise bean's method while the client is associated with a transaction context, the container invokes the enterprise bean's method in the client's transaction context.

  *

  REQUIRES_NEW

  The container must invoke an enterprise bean method whose transaction attribute is set to REQUIRES_NEW with a new transaction context.

  Reference: TransactionAttributeType.MANDATORY

• Question 6:

  A developer creates a stateful session bean that is used by many concurrent clients. The clients are written by other development team; and it is assumed that these clients might not remove the bean when ending their session. The number

  of concurrent sessions will be greater than the defined bean cache size.

  The developer must consider that the state of the session bean can be influenced by either passivation or timeout.

  Which three actions should the developer take to make the bean behave correctly in passivation and timeout situations? (Choose three.)

  A. Release references to resources in a @Remove annotated method.
  B. Re-establish references to resources in an @Init annotated method.
  C. Release references to resources in a @PreDestroy annotated method.
  D. Release references to resources in a @PrePassivate annotated method.
  E. Re-establish references to resources in a @PostActivate annotated method.
  C. Release references to resources in a @PreDestroy annotated method.
  D. Release references to resources in a @PrePassivate annotated method.
  E. Re-establish references to resources in a @PostActivate annotated method.

• Question 7:

  While excepting a business method in a stateless session bean the container rolls back the method's transaction. Which three are possible causes for the container's behavior? (Choose three.)

  A. The bean uses container-managed transactions and invokes EJBContext.setRollbackOnly.
  B. The bean uses container-managed transactions and invokes EJBContext.getRollbackOnly.
  C. The business method throws a java.lang.NullPointerException.
  D. The business method throws a checked exception of a class type that is marked with the @ApplicationException annotation with the rollback element value true.
  E. The business method throws a unchecked exception of a class type that is marked with the @ApplicationException annotation with the rollback element value true.
  F. The bean uses container-managed transactions and throws a checked exception of a class type that is marked with the @ApplicationException annotation with the rollback element value false.
  A. The bean uses container-managed transactions and invokes EJBContext.setRollbackOnly.
  D. The business method throws a checked exception of a class type that is marked with the @ApplicationException annotation with the rollback element value true.
  F. The bean uses container-managed transactions and throws a checked exception of a class type that is marked with the @ApplicationException annotation with the rollback element value false.

  ---

  A: setRollbackOnly

  Mark the current transaction for rollback. The transaction will become permanently marked for rollback. A transaction marked for rollback can never commit. Only enterprise beans with container-managed transactions are allowed to use this

  method.

  Note:

  *

  In a stateless session bean with bean-managed transactions, a business method must commit or roll back a transaction before returning.

  *

  Bean-Managed Transactions

  In bean-managed transaction demarcation, the code in the session or message-driven bean explicitly marks the boundaries of the transaction. Although beans with container-managed transactions require less coding, they have one limitation:

  When a method is executing, it can be associated with either a single transaction or no transaction at all. If this limitation will make coding your bean difficult, you should consider using bean-managed transactions.

  *

  (incorrect) Unchecked runtime exceptions represent conditions that, generally speaking, reflect errors in your program's logic and cannot be reasonably recovered from at run time. Incorrect:

  B: getRollbackOnly

  Test if the transaction has been marked for rollback only. An enterprise bean instance can use this operation, for example, to test after an exception has been caught, whether it is fruitless to continue computation on behalf of the current transaction. Only enterprise beans with container- managed transactions are allowed to use this method.

• Question 8:

  Which must result in the destruction of a stateful session bean?

  A. A client calls an @Remove method and the method returns successfully.
  B. The server in which the stateful session bean was created is restarted.
  C. The stateful session bean participates in a transaction that is rolled back.
  D. The stateful session bean is chosen as a last recently used (LRU) victim for passivation.
  A. A client calls an @Remove method and the method returns successfully.

  ---

  While in the ready stage, the EJB container may decide to deactivate, or passivate, the bean by moving it from memory to secondary storage. (Typically, the EJB container uses a least- recently-used algorithm to select a bean for passivation.) The EJB container invokes the method annotated @PrePassivate, if any, immediately before passivating it. If a client invokes a business method on the bean while it is in the passive stage, the EJB container activates the bean, calls the method annotated @PostActivate, if any, and then moves it to the ready stage.

  Note:

  At the end of the lifecycle, the client invokes a method annotated @Remove, and the EJB container calls the method annotated @PreDestroy, if any. The bean's instance is then ready for garbage collection.

  *

  When a stateful bean is passivated, the instance fields are read and then written to the secondary storage associated with the EJB object. When the stateful session bean has been successfully passivated, the instance is evicted from memory; it is destroyed.

  *

  When a passivated bean instance times out or when a client invokes the method marked with @Remove, the container may destroy the bean. Before destroying, the container will invoke the method annotated with @PreDestroy.

  Reference: The Java EE 6 Tutorial, The Lifecycles of Enterprise Beans

• Question 9:

  A developer wants to create an enterprise bean that uses the EJB Timer service. Which two are true? (Choose two.)

  A. Once created, a timer cannot be canceled.
  B. The bean can be used within a transaction.
  C. Once created, the timer will survive a container crash.
  D. The enterprise bean must implement the TimedObject interface.
  E. The developer can use either a message-driven bean, stateless session bean, or stateful session bean.
  B. The bean can be used within a transaction.
  C. Once created, the timer will survive a container crash.

  ---

  B: An enterprise bean usually creates a timer within a transaction. If this transaction is rolled back, the timer creation also is rolled back. Similarly, if a bean cancels a timer within a transaction that gets rolled back, the timer cancellation is rolled back.

  C: Timers are persistent by default. If the server is shut down or crashes, persistent timers are saved and will become active again when the server is restarted. If a persistent timer expires while the server is down, the container will call the @Timeout method when the server is restarted.

  Incorrect answers:

  A: Timers can be cancelled by the following events.

  *

  When a single-event timer expires, the EJB container calls the associated timeout method and then cancels the timer.

  *

  When the bean invokes the cancel method of the Timer interface, the container cancels the timer.

  Reference: The Java EE 6Tutorial. PartNo: 821 Transactions andTimers

• Question 10:

  A developer writes a stateless session bean with one local business interface and with container- managed transactions. All business methods have transaction attribute REQUIRED. The bean has an injected field sessionCtx of the type SessionContext. Which two operations are allowed in a business method of the bean? (Choose two.)

  A. sessionCtx. getEJBObject
  B. sessionCtx.setRollbackOnly
  C. sessionCtx. getMessageContext
  D. sessionCtx. getBusinessObject
  E. sessionCtx. getEJBLocalObject
  B. sessionCtx.setRollbackOnly
  D. sessionCtx. getBusinessObject