J2EE Questions et reponses d'entretien

Question 1. What makes J2EE suitable for distributed multitiered Applications?

The J2EE platform uses a multitiered distributed application model. Application logic is divided into components according to function, and the various application components that make up a J2EE application are installed on different machines depending on the tier in the multitiered J2EE environment to which the application component belongs. The J2EE application parts are:

• Client-tier components run on the client machine.


• Web-tier components run on the J2EE server.


• Business-tier components run on the J2EE server.


• Enterprise information system (EIS)-tier software runs on the EIS server.

Question 2. What is J2EE?

J2EE is an environment for developing and deploying enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing multitiered, web-based applications.

Question 3. What are the components of J2EE application?

A J2EE component is a self-contained functional software unit that is assembled into a J2EE application with its related classes and files and communicates with other components. The J2EE specification defines the following J2EE components:

• Application clients and applets are client components.
  
• Java Servlet and JavaServer Pages technology components are web components.
  
• Enterprise JavaBeans components (enterprise beans) are business components.
  
• Resource adapter components provided by EIS and tool vendors.
  

Question 4. What do Enterprise JavaBeans components contain?

Enterprise JavaBeans components contains Business code, which is logic that solves or meets the needs of a particular business domain such as banking, retail, or finance, is handled by enterprise beans running in the business tier. All the business code is contained inside an Enterprise Bean which receives data from client programs, processes it (if necessary), and sends it to the enterprise information system tier for storage. An enterprise bean also retrieves data from storage, processes it (if necessary), and sends it back to the client program.

Question 5. Is J2EE application only a web-based?

No. It depends on type of application that client wants. A J2EE application can be web-based or non-web-based. if an application client executes on the client machine, it is a non-web-based J2EE application. The J2EE application can provide a way for users to handle tasks such as J2EE system or application administration. It typically has a graphical user interface created from Swing or AWT APIs, or a command-line interface. When user request, it can open an HTTP connection to establish communication with a servlet running in the web tier.