Jakarta Enterprise Beans: Session Beans Overview

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Questions and Answers

Which lifecycle method can exclusively be defined in the bean class?

@PostConstruct

@Remove (correct)

@PostActivate

@PreDestroy

What must each method in an interceptor class accept as its argument?

InvocationContext (correct)

BeanContext

ContextHandler

MethodInvocation

When is the @AroundInvoke interceptor method triggered?

Before the bean is constructed

Before the bean is destroyed

When the business method is invoked (correct)

After the business method is executed

What annotation is used to define an interceptor class?

@Interceptor Signup and view all the answers

What does the @AroundInvoke method return in the interceptor chain?

InvocationContext.proceed() Signup and view all the answers

What are the two types of enterprise beans mentioned?

Session beans and Message-Driven Beans Signup and view all the answers

What is the primary function of session beans?

To serve as method invocation components Signup and view all the answers

Which statement accurately describes Message-Driven Beans?

They are designed for asynchronous message handling. Signup and view all the answers

Which of the following is NOT a characteristic of session beans?

They can handle asynchronous processing. Signup and view all the answers

What is the role of enterprise beans in Jakarta EE?

To implement business logic and process data. Signup and view all the answers

Which of the following best describes the Invocation mode of session beans?

Clients can invoke them via local or remote interfaces. Signup and view all the answers

In the context of Jakarta Enterprise Beans, what does EJB stand for?

Enterprise Java Beans Signup and view all the answers

What distinguishes message-driven beans from session beans?

Message-driven beans receive and process messages asynchronously. Signup and view all the answers

What is a primary role of session beans in business applications?

Handling business logic for transactions Signup and view all the answers

Which of the following accurately describes the lifecycle of session beans?

They can be pooled and reused to improve performance Signup and view all the answers

What is the purpose of asynchronous method invocation in session beans?

To execute methods in a separate thread and not block the caller Signup and view all the answers

Which of the following is a characteristic of Message-Driven Beans?

They process messages from a message broker asynchronously Signup and view all the answers

What is one important aspect of the lifecycle of Message-Driven Beans?

They are created and managed by the EJB container Signup and view all the answers

Which of the following best describes the relationship between session beans and transactions?

Session beans can manage multiple transactions within a single instance Signup and view all the answers

Which option is a benefit of using Enterprise JavaBeans (EJB) in application development?

It allows developers to focus on business logic rather than infrastructure Signup and view all the answers

What is a common misconception regarding session beans?

Stateful session beans must maintain conversations across method calls Signup and view all the answers

What method can be used by the client to check if an invocation was cancelled on the server side?

Future.isCancelled Signup and view all the answers

Which method blocks the client until the invocation completes?

Future.get Signup and view all the answers

What does the cancel method return if the cancellation was successful?

True Signup and view all the answers

What does the mayInterruptIfRunning parameter indicate when cancelling an invocation?

If the invocation is currently running, it should be forcibly stopped. Signup and view all the answers

Which method would allow a client to determine if processing has completed before calling a blocking get method?

Future.isDone Signup and view all the answers

What happens if the cancel method is invoked but the method invocation cannot be cancelled?

The method invocation continues without interruption. Signup and view all the answers

Which method returns true if mayInterruptIfRunning is set to true and the session bean recognizes the cancellation?

SessionContext.wasCancelled Signup and view all the answers

When should the Future.get method typically be used?

When the client wants to retrieve the result of an asynchronous operation. Signup and view all the answers

What are the three types of session beans in EJB technology?

Stateful, stateless, singleton Signup and view all the answers

What is a primary characteristic of stateless session beans?

They allow for greater scalability and efficiency. Signup and view all the answers

Which type of session bean would be most suitable for maintaining state information across multiple method calls?

Stateful session bean Signup and view all the answers

In what scenario might remote clients be favored over local clients when invoking session beans?

When the client and server are on different networks. Signup and view all the answers

What is the main advantage of using singleton session beans?

They provide a shared instance across all clients. Signup and view all the answers

Which characteristic is NOT associated with stateless session beans?

They must store client data for multiple requests. Signup and view all the answers

What is a key consideration when deciding between local and remote client invocation for session beans?

The geographical location of the client. Signup and view all the answers

Which type of bean is specifically not a session bean?

Entity bean Signup and view all the answers

Study Notes

Jakarta Enterprise Beans (II)

Session Beans are components in Jakarta EE that interact with clients and have different types, each with its own characteristics.
- Stateful beans retain information between client calls but are not shared across them.
- Stateless beans do not hold state and are shared by multiple clients.
- Singleton beans are single instances, useful for global data access.
Session bean invocations can be local or remote for flexibility and performance optimization.
Lifecycle Methods are automatically executed by the container, allowing for pre- and post-processing logic.
- Examples include:
  - @PostConstruct - Before bean construction
  - @PrePassivate - Before bean is passivated
  - @PostActivate - After bean is activated
  - @Remove - Before bean destruction
  - @PreDestroy - Before bean destruction
Interceptors methods are automatically invoked by the container when business methods are called, allowing for cross-cutting concerns.
- Examples include:
  - @AroundConstruct - When the constructor is invoked
  - @AroundInvoke - When a business method is invoked
Interceptors can be defined within the bean class or as a separate class.
Asynchronous Method Invocation allows client calls to return immediately, while the session bean handles processing in the background.
- This can improve responsiveness for clients.
- Asynchronous methods return a Future object, enabling clients to check the status or wait for results later.
- Future.isDone() checks if the method has finished processing.
- Future.get() retrieves the result of the asynchronous call, potentially blocking the client until completion.
Clients have the option to cancel asynchronous method invocations.
- Future.isCancelled() indicates whether the method has been cancelled.
- Future.cancel(boolean mayInterruptIfRunning) attempts to cancel the method invocation, returning true if successful.
- mayInterruptIfRunning determines the behavior of the SessionContext.wasCancelled() method if cancellation fails.

Message-Driven Beans (MDB)

MDBs are specifically designed for asynchronous message handling.
They are not directly invoked by clients but receive messages from message queues or topics.
Each MDB instance handles messages according to its configuration and defined methods.
MDBs support various message types like JMS (Java Message Service).
They offer reliable asynchronous message processing and decoupling between senders and receivers.
Similar to Session Beans, MDBs have lifecycle methods.
- @PostConstruct - After bean construction
- @PreDestroy - Before bean destruction
- @OnMessage - When a message arrives on the specified queue or topic.

Development Concepts

Jakarta Persistence (JPA) facilitates object-relational mapping (ORM) for persisting Java objects to databases.
Jakarta Enterprise Web Services enable interoperable communication between applications using web service standards.
Distributed Computing principles are used to design and develop systems that utilize multiple interconnected components across different physical locations.
Enterprise Systems Architecture considers the overall structure, components, and principles governing complex enterprise-level systems.
Enterprise Systems Security addresses the protection of enterprise systems from threats and unauthorized access.
Enterprise Systems Testing encompasses various methods and techniques for verifying the functionality, performance, and security of enterprise systems.
Enterprise Systems Configuration Management helps manage and track changes to enterprise systems to ensure consistency and reliability.
Advanced Development involves more intricate and specialized techniques for building complex enterprise applications.

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Description

This quiz covers the different types of session beans in Jakarta EE, including stateful, stateless, and singleton beans, along with their lifecycle methods and invocation types. Understand how these components interact with clients and the significance of interceptors in managing business methods.