1 . 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 multi tiered, and web-based applications.
2 . What is the J2EE module?
- A J2EE module consists of one or more J2EE components for the same container type and one component deployment descriptor of that type.
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:
4 . Application clients and applets are client components.
- Java Servlets and Java Server PagesTM (JSPTM) technology components are web components.
Enterprise JavaBeansTM (EJBTM) components (enterprise beans) are business components.
Resource adapter components provided by EIS and tool vendors.
5 . What are the four types of J2EE modules?
- Application client module
- Web module
- Enterprise JavaBeans module
- Resource adapter module
6 . What does application client module contain?
- The application client module contains:
an application client deployment descriptor.
Application client modules are packaged as JAR files with a .jar extension.
7 . What does Enterprise JavaBeans module contain?
- The Enterprise JavaBeans module contains: class files for enterprise beans An EJB deployment descriptor. EJB modules are packaged as JAR files with a .jar extension.
8 . What does resource adapt module contain?
- The resource adapt module contains:
- all Java interfaces, classes,
- native libraries,
- other documentation,
- A resource adapter deployment descriptor.
- Resource adapter modules are packages as JAR files with a .rar (Resource adapter Archive) extension.
9 . What are the differences between Ear, Jar and War files? Under what circumstances should we use each one?
- There are no structural differences between the files;
they are all archived using zip-jar compression. However, they are intended for different purposes.
- Jar files (files with a .jar extension) arre intended to hold generic libraries of Java classes, resources, auxiliary files, etc.
- War files (files with a .war extension) arre intended to contain complete Web applications. In this context, a Web application is defined as a single group of files, classes, resources, .jar files that can be packaged and accessed as one servlet context.
- Ear files (files with a .ear extension) arre intended to contain complete enterprise applications. In this context, an enterprise application is defined as a collection of .jar files, resources, classes, and multiple Web applications.
- Each type of file (.jar, .war, .ear) is processed uniquely by application servers, servlet containers, EJB containers, etc.
10 . What is the difference between Session bean and Entity bean?one?The Session bean and Entity bean are two main parts of EJB container.
11 . What is "applet" ?
- A J2EE component that typically executes in a Web browser but can execute in a variety of other applications or devices that support the applet programming model.
12 . What is "applet container" ?
- A container that includes support for the applet programming model.
13 . What is "application assembler" ?
- A person who combines J2EE components and modules into deployable application units.
14 . What is "application client" ?
- A first-tier J2EE client component that executes in its own Java virtual machine. Application clients have access to some J2EE platform APIs.
15 . What is "application client container" ?
- A container that supports application client components.
16 . What is "application client module" ?
- A software unit that consists of one or more classes and an application client deployment descriptor.
17 . What is "application component provider" ?
- A vendor that provides the Java classes that implement components' methods, JSP page definitions, and any required deployment descriptors.
18 . What is "application configuration resource file" ?
- An XML file used to configure resources for a JavaServer Faces application, to define navigation rules for the application, and to register converters, validators, listeners, renderers, and components with the application.
19 . What is "archiving" ?
- The process of saving the state of an object and restoring it.
20 . What is "asant" ?
- A Java-based build tool that can be extended using Java classes. The configuration files are XML-based, calling out a target tree where various tasks get executed.
21 . What is "attribute"What is "asant" ?
- A qualifier on an XML tag that provides additional information.
22 . What is authentication ?
- The process that verifies the identity of a user, device, or other entity in a computer system, usually as a prerequisite to allowing access to resources in a system. The Java servlet specification requires three types of authentication-basic, form-based, and mutual-and supports digest authentication.
23 . What is authorization?
- The process by which access to a method or resource is determined. Authorization depends on the determination of whether the principal associated with a request through authentication is in a given security role. A security role is a logical grouping of users defined by the person who assembles the application. A deployer maps security roles to security identities. Security identities may be principals or groups in the operational environment.
24 . Is J2EE application only a web-based?
- NO. 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.