Java EE Benefits and Servlets Overview

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Questions and Answers

Which of the following is a characteristic of Java EE?

Low availability

Limited multi-platform support

Scalability (correct)

Single vendor reliance

Which method is called only once during a servlet's lifecycle?

service()

destroy()

init() (correct)

doGet()

What is the primary role of a servlet container?

To provide database connectivity

To interface with Java servlets and manage their lifecycle (correct)

To manage web server load balancing

To generate static web pages

Which of the following methods allows a servlet to process client requests based on the HTTP method?

service() Signup and view all the answers

What is the significance of the destroy() method in a servlet?

To release resources before the servlet is removed from service Signup and view all the answers

What flexibility does Java EE offer regarding application servers?

Freedom to choose vendors for application servers and components Signup and view all the answers

What type of systems does Java EE integrate with?

Existing systems across various platforms Signup and view all the answers

What does the getServletConfig() method provide access to?

Servlet-specific configuration parameters Signup and view all the answers

What is the primary purpose of an application server?

Provides a platform for running applications and business logic Signup and view all the answers

Which of the following servers is primarily used for serving static content?

Web Server Signup and view all the answers

What distinguishes a web server from an application server?

Web servers deliver web pages while application servers run applications and business logic. Signup and view all the answers

Which component is responsible for managing the execution of enterprise beans in Java EE applications?

EJB container Signup and view all the answers

Which API provides asynchronous messaging in Java EE?

Java Message Service (JMS) Signup and view all the answers

What service does the Java Persistence API (JPA) primarily provide?

Object Relational Mapping (ORM) Signup and view all the answers

Which protocol is commonly used by application servers?

RMI or IIOP Signup and view all the answers

What role does the web container play in Java EE?

Manages the execution of web pages and servlets Signup and view all the answers

Which of the following is NOT an advantage of using Enterprise JavaBeans (EJB)?

Requires extensive manual coding Signup and view all the answers

What is a primary function of an EJB Container?

Managing the lifecycle of EJB components Signup and view all the answers

In what scenario would using Enterprise JavaBeans (EJB) be most appropriate?

When requiring distributed access across different locations Signup and view all the answers

What type of EJB maintains a specific state across multiple method calls for a client?

Stateful Session Bean Signup and view all the answers

Which feature of EJB supports efficient resource utilization in a multi-threaded environment?

Object pooling Signup and view all the answers

Which statement best describes the encapsulation of business logic in EJB?

Separates business logic from presentation and persistence layers. Signup and view all the answers

What does EJB's built-in transaction management ensure?

Data integrity is maintained across application transactions. Signup and view all the answers

Which type of session bean does NOT maintain any client-specific state between method calls?

Stateless Session Bean Signup and view all the answers

Study Notes

Java EE Benefits

Ensures high availability to support continuous operation of applications.
Offers scalability to accommodate growing workloads and user demands.
Facilitates integration with existing systems for seamless operation.
Provides freedom to select vendors, tools, and application servers.
Supports a multi-platform approach for cross-environment compatibility.
Enhances flexibility for various scenarios and diverse client types.
Improves programming productivity through reusable components and tools.

Introduction to Servlets

A servlet is a Java component designed to extend a web server’s capabilities by providing custom services.
Servlet Container (or web container) manages servlets and handles their lifecycle. Example: Apache Tomcat.

Servlet Life Cycle

Consists of init(), service(), and destroy() methods that manage servlet operations.
init(): Initializes servlet, called once during its lifecycle for setup.
service(): Core method for processing client requests, can invoke doGet() or doPost().
destroy(): Cleans up resources when the servlet is taken out of service, called once.

Ancillary Methods of Servlets

getServletConfig(): Retrieves servlet-specific configuration information and parameters.
getServletInfo(): Provides metadata about the servlet, useful for documentation.

Handling Dynamic Requests

Begins when a user interacts with a link directing to a servlet.
Security and integration features improve resilience and connectivity in web development frameworks.

Enterprise JavaBeans (EJB)

An EJB represents a framework for developing large-scale distributed business applications on the Java platform.
Requires an EJB Container (e.g., WildFly, GlassFish) for key services like lifecycle management and security.

When to Use EJB

Ideal for applications needing remote access across diverse locations.
Supports scalability through load balancing and clustering.
Separates business logic from presentation, allowing cleaner architecture.

Advantages of EJB

Reusability: Components easily integrated into various applications (e.g., Visual Age).
Visual Development: EJBs can be visually combined using IDEs to enhance productivity.
Facilitates multithreading for resource efficiency.
Simplifies database access (e.g., JDBC) and network communications (e.g., RMI).
Provides transaction management, easing manual coding efforts.
Offers well-defined interfaces for interaction between different EJBs.

EJB Types

Session Beans: Perform tasks for clients categorized as:
- Stateless: No maintenance of client-specific state across calls.
- Stateful: Maintains state for specific client over multiple calls.

Servers Overview

A server responds to client requests over a network; types include:
- Web Server: Delivers static content (e.g., HTML).
- Application Server: Runs applications and business logic.
- FTP Server: Manages file transfers.
- Online Game Server: Supports multiplayer gaming environment.

Web Server vs. Application Server

Web Server: Delivers web pages and serves static content via HTTP.
Application Server: Handles dynamic content and manages business logic with various protocols (e.g., RMI).

Java EE Servers and Containers

Java EE Server: Runtime component providing EJB and web containers.
EJB Container: Manages EJB execution.
Web Container: Oversees execution of web pages and servlets.
Application Client Container: Executes client components.
Applet Container: Manages applet execution through a web browser.

Java EE Services

Messaging: Java Message Service (JMS) enables asynchronous messaging.
Transaction: Implemented by Java Transaction API (JTA) for transaction management.
Persistence: Managed by Java Persistence API (JPA) for ORM and database operations.
Web Service: JAX-RS and JAX-WS support REST and SOAP services.
Contexts & Dependency Injection: CDI promotes loosely coupled resource injection.

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Description

Explore the advantages of Java EE, including high availability, scalability, and multi-platform flexibility. This quiz also delves into servlets as a vital Java component that enhances web server capabilities. Test your knowledge on the integration and productivity aspects of Java EE.