Java Enterprise and Web Technologies

Rule Execution Servers handle runtime operations: deploying packaged ruleapps and rule projects, and monitoring their execution. BOM (business object model) to XOM (execution object model) mapping is a build-time transformation performed by development tools like Rule Studio, not the execution server.

Enterprise JavaBeans (EJBs) differ from regular JavaBeans in three key ways: EJBs are managed by an EJB container that handles lifecycle, security, and transactions; they execute on the server side in application servers; and they can participate in distributed transactions. Regular JavaBeans are simple reusable components that run client-side without container management.

When a request arrives for an EJB method, the container performs several preprocessing tasks before invoking the bean: it can start a transaction context if the method requires one, and it checks security credentials to verify the client's authorization. The container does not simply pass requests directly - it provides these middleware services first.

Stateful session beans maintain conversational state with a specific client. The correct answer is D because stateful session beans can receive initial state information through arguments in their create methods. Option A is incorrect because while there's a relationship, it's not accurately described as many-to-one. Option B is false because bean instances have a finite lifecycle. Option C is incorrect because the container doesn't arbitrarily discard stateful beans - passivation/activation follows specific rules. Option E is false because instances are created on client demand, not deployment.

Entity beans represent persistent business data. Option D is correct because entity beans represent persistent data with unique primary key identification. Option A is incorrect because multiple clients can access the same entity bean instance. Option B is false because containers can discard/passivate entity beans to manage resources. Option C is misleading because while instances have identity within the container, the question's phrasing is imprecise. Entity beans fundamentally exist to represent data in persistent storage.

Entity beans represent data in persistent storage that can be accessed by multiple clients concurrently. The answer is False because entity beans do NOT have a one-to-one relationship with clients. Multiple clients can access the same entity bean instance (representing the same underlying data) simultaneously. Entity beans are designed for shared access to persistent data, unlike stateful session beans which maintain exclusive conversational state with one client.

In EJB, a bean's remote interface can extend other remote interfaces using Java's extends clause. This is True because remote interfaces are standard Java interfaces that follow normal inheritance rules. A bean's remote interface can extend from other remote interfaces (or regular interfaces), allowing interface hierarchies and code reuse. The bean implementation class then implements this extended interface, inheriting all method signatures.

EJB callback methods like ejbCreate and ejbRemove have standardized signatures in the EJB specification, but their internal implementation varies by application server vendor. The answer is True because while the API contract is the same (method names, signatures, and behavior requirements), each vendor (WebLogic, JBoss, WebSphere, etc.) implements these differently internally. The container manages the bean lifecycle, and vendor implementations optimize this differently.

Message Driven Beans (MDBs) share structural similarities with Session Beans. The answer is True because MDBs follow the same lifecycle callback pattern (ejbCreate, ejbRemove) as session beans, and they're also managed by the container. The key difference is MDBs don't have a client-visible interface - they respond to JMS messages instead of direct client calls. But structurally, they mimic session bean patterns for lifecycle management.

A thin-client application is characterized by minimal processing on the client side. The client primarily handles the user interface and passes data to server-side components (like enterprise beans) for actual business logic and data processing. This reduces client-side resource requirements.

A J2EE component is a self-contained, reusable software unit that is assembled into a J2EE application. Components like EJBs, servlets, and JSPs have defined interfaces and interact with other components through containers, enabling modular enterprise application development.

Entity beans represent persistent business data that survives system crashes because they are backed by a database. Session beans, in contrast, are transient and only exist for the duration of a client session, representing business processes rather than persistent state.

Session beans are designed for transient, short-lived operations that don't need to survive crashes. They process business logic that can be restarted if lost. Persistence between program invocations requires entity beans or database storage. Database transactions can be initiated from various components, not just session beans.

Separating user data entry (JSP) from business logic (JavaBeans) follows the Model-View-Controller pattern, making applications easier to maintain and update. Changes to the UI (JSP) don't affect business logic (JavaBeans), and vice versa. This is about maintainability, not security, deployment, or visual interest.