J2EE Interview Questions and Answers 5

What is deployment descriptor ?
An XML file provided with each module and J2EE application that describes how they should be deployed. The deployment descriptor directs a deployment tool to deploy a module or application with specific container options and describes specific configuration requirements that a deployer must resolve.

What is destination ?
A JMS administered object that encapsulates the identity of a JMS queue or topic. See point-to-point messaging system, publish/subscribe messaging system.

What is digest authentication ?
An authentication mechanism in which a Web application authenticates itself to a Web server by sending the server a message digest along with its HTTP request message. The digest is computed by employing a one-way hash algorithm to a concatenation of the HTTP request message and the client's password. The digest is typically much smaller than the HTTP request and doesn't contain the password.

What is distributed application ?
An application made up of distinct components running in separate runtime environments, usually on different platforms connected via a network. Typical distributed applications are two-tier (client-server), three-tier (client-middleware-server), and multitier (client-multiple middleware-multiple servers).

What is document ?
In general, an XML structure in which one or more elements contains text intermixed with subelements.

What is Document Object Model ?
An API for accessing and manipulating XML documents as tree structures. DOM provides platform-neutral, language-neutral interfaces that enables programs and scripts to dynamically access and modify content and structure in XML documents.

What is document root ?
The top-level directory of a WAR. The document root is where JSP pages, client-side classes and archives, and static Web resources are stored.

What is DTD ?
Document type definition. An optional part of the XML document prolog, as specified by the XML standard. The DTD specifies constraints on the valid tags and tag sequences that can be in the document. The DTD has a number of shortcomings, however, and this has led to various schema proposals. For example, the DTD entry says that the XML element called username contains parsed character data-that is, text alone, with no other structural elements under it. The DTD includes both the local subset, defined in the current file, and the external subset, which consists of the definitions contained in external DTD files that are referenced in the local subset using a parameter entity.

What is durable subscription ?
In a JMS publish/subscribe messaging system, a subscription that continues to exist whether or not there is a current active subscriber object. If there is no active subscriber, the JMS provider retains the subscription's messages until they are received by the subscription or until they expire.

What is EAR file ?
Enterprise Archive file. A JAR archive that contains a J2EE application.

What is ebXML ?
Electronic Business XML. A group of specifications designed to enable enterprises to conduct business through the exchange of XML-based messages. It is sponsored by OASIS and the United Nations Centre for the Facilitation of Procedures and Practices in Administration, Commerce and Transport (U.N./CEFACT).

What is EJB ?
Enterprise JavaBeans.

What is EJB container ?
A container that implements the EJB component contract of the J2EE architecture. This contract specifies a runtime environment for enterprise beans that includes security, concurrency, life-cycle management, transactions, deployment, naming, and other services. An EJB container is provided by an EJB or J2EE server.

What is EJB container provider ?
A vendor that supplies an EJB container.

What is EJB context ?
A vendor that supplies an EJB container. An object that allows an enterprise bean to invoke services provided by the container and to obtain the information about the caller of a client-invoked method.

J2EE Interview Questions and Answers 4

What is container-managed sign-on ?
The mechanism whereby security information needed for signing on to a resource is supplied by the container.

What is container-managed transaction ?
A transaction whose boundaries are defined by an EJB container. An entity bean must use container-managed transactions.

What is content ?
In an XML document, the part that occurs after the prolog, including the root element and everything it contains.

What is context attribute ?
An object bound into the context associated with a servlet.

What is context root ?
A name that gets mapped to the document root of a Web application.

What is conversational state ?
The field values of a session bean plus the transitive closure of the objects reachable from the bean's fields. The transitive closure of a bean is defined in terms of the serialization protocol for the Java programming language, that is, the fields that would be stored by serializing the bean instance.

What is CORBA ?
Common Object Request Broker Architecture. A language-independent distributed object model specified by the OMG.

What is create method ?
A method defined in the Interview Questions - Home interface and invoked by a client to create an enterprise bean.

What is credentials ?
The information describing the security attributes of a principal.

What is CSS ?
Cascading style sheet. A stylesheet used with HTML and XML documents to add a style to all elements marked with a particular tag, for the direction of browsers or other presentation mechanisms.

What is CTS ?
Compatibility test suite. A suite of compatibility tests for verifying that a J2EE product complies with the J2EE platform specification.

What is data ?
The contents of an element in an XML stream, generally used when the element does not contain any subelements. When it does, the term content is generally used. When the only text in an XML structure is contained in simple elements and when elements that have subelements have little or no data mixed in, then that structure is often thought of as XML data, as opposed to an XML document.

What is DDP ?
Document-driven programming. The use of XML to define applications.

What is declaration ?
The very first thing in an XML document, which declares it as XML. The minimal declaration is . The declaration is part of the document prolog.

What is declarative security ?
Mechanisms used in an application that are expressed in a declarative syntax in a deployment descriptor.

What is delegation ?
An act whereby one principal authorizes another principal to use its identity or privileges with some restrictions.

What is deployer ?
A person who installs J2EE modules and applications into an operational environment.

What is deployment ?
The process whereby software is installed into an operational environment.

J2EE Interview Questions and Answers 6

What is EJB Home object ?
An object that provides the life-cycle operations (create, remove, find) for an enterprise bean. The class for the EJB Home object is generated by the container's deployment tools. The EJB Home object implements the enterprise bean's Home interface. The client references an EJB Home object to perform life-cycle operations on an EJB object. The client uses JNDI to locate an EJB Home object.

What is EJB JAR file ?
A JAR archive that contains an EJB module.

What is EJB module ?
A deployable unit that consists of one or more enterprise beans and an EJB deployment descriptor.

What is EJB object ?
An object whose class implements the enterprise bean's remote interface. A client never references an enterprise bean instance directly; a client always references an EJB object. The class of an EJB object is generated by a container's deployment tools.

What is EJB server ?
Software that provides services to an EJB container. For example, an EJB container typically relies on a transaction manager that is part of the EJB server to perform the two-phase commit across all the participating resource managers. The J2EE architecture assumes that an EJB container is hosted by an EJB server from the same vendor, so it does not specify the contract between these two entities. An EJB server can host one or more EJB containers.

What is EJB server provider ?
A vendor that supplies an EJB server.

What is element ?
A unit of XML data, delimited by tags. An XML element can enclose other elements.

What is empty tag ?
A tag that does not enclose any content.

What is enterprise bean ?
A J2EE component that implements a business task or business entity and is hosted by an EJB container; either an entity bean, a session bean, or a message-driven bean.

What is enterprise bean provider ?
An application developer who produces enterprise bean classes, remote and Interview Questions - Home interfaces, and deployment descriptor files, and packages them in an EJB JAR file.

What is enterprise information system ?
The applications that constitute an enterprise's existing system for handling companywide information. These applications provide an information infrastructure for an enterprise. An enterprise information system offers a well-defined set of services to its clients. These services are exposed to clients as local or remote interfaces or both. Examples of enterprise information systems include enterprise resource planning systems, mainframe transaction processing systems, and legacy database systems.

What is enterprise information system resource ?
An entity that provides enterprise information system-specific functionality to its clients. Examples are a record or set of records in a database system, a business object in an enterprise resource planning system, and a transaction program in a transaction processing system.

What is Enterprise JavaBeans (EJB) ?
A component architecture for the development and deployment of object-oriented, distributed, enterprise-level applications. Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and secure.

What is Enterprise JavaBeans Query Language (EJB QL) ?
Defines the queries for the finder and select methods of an entity bean having container-managed persistence. A subset of SQL92, EJB QL has extensions that allow navigation over the relationships defined in an entity bean's abstract schema.

What is an entity ?
A distinct, individual item that can be included in an XML document by referencing it. Such an entity reference can name an entity as small as a character (for example, <, which references the less-than symbol or left angle bracket, <). An entity reference can also reference an entire document, an external entity, or a collection of DTD definitions.

J2EE Interview Questions and Answers 7

What is entity bean ?
An enterprise bean that represents persistent data maintained in a database. An entity bean can manage its own persistence or can delegate this function to its container. An entity bean is identified by a primary key. If the container in which an entity bean is hosted crashes, the entity bean, its primary key, and any remote references survive the crash.

What is entity reference ?
A reference to an entity that is substituted for the reference when the XML document is parsed. It can reference a predefined entity such as <>

What is error ?
A SAX parsing error is generally a validation error; in other words, it occurs when an XML document is not valid, although it can also occur if the declaration specifies an XML version that the parser cannot handle. See also fatal error, warning.

What is Extensible Markup Language ?
XML.

What is external entity ?
An entity that exists as an external XML file, which is included in the XML document using an entity reference.

What is external subset ?
That part of a DTD that is defined by references to external DTD files.

What is fatal error ?
A fatal error occurs in the SAX parser when a document is not well formed or otherwise cannot be processed. See also error, warning.

What is filter ?
An object that can transform the header or content (or both) of a request or response. Filters differ from Web components in that they usually do not themselves create responses but rather modify or adapt the requests for a resource, and modify or adapt responses from a resource. A filter should not have any dependencies on a Web resource for which it is acting as a filter so that it can be composable with more than one type of Web resource.

What is filter chain ?
A concatenation of XSLT transformations in which the output of one transformation becomes the input of the next.

What is finder method ?
A method defined in the Interview Questions - Home interface and invoked by a client to locate an entity bean.

What is form-based authentication ?
An authentication mechanism in which a Web container provides an application-specific form for logging in. This form of authentication uses Base64 encoding and can expose user names and passwords

What is general entity ?
An entity that is referenced as part of an XML document's content, as distinct from a parameter entity, which is referenced in the DTD. A general entity can be a parsed entity or an unparsed entity.

What is group ?
An authenticated set of users classified by common traits such as job title or customer profile. Groups are also associated with a set of roles, and every user that is a member of a group inherits all the roles assigned to that group.

What is handle ?
An object that identifies an enterprise bean. A client can serialize the handle and then later deserialize it to obtain a reference to the enterprise bean.

What is Interview Questions - Home handle ?
An object that can be used to obtain a reference to the Interview Questions - Home interface. A Interview Questions - Home handle can be serialized and written to stable storage and de-serialized to obtain the reference.

What is Interview Questions - Home interface ?
One of two interfaces for an enterprise bean. The Interview Questions - Home interface defines zero or more methods for managing an enterprise bean. The Interview Questions - Home interface of a session bean defines create and remove methods, whereas the Interview Questions - Home interface of an entity bean defines create, finder, and remove methods.

J2EE Interview Questions and Answers 8

What is HTML ?
Hypertext Markup Language. A markup language for hypertext documents on the Internet. HTML enables the embedding of images, sounds, video streams, form fields, references to other objects with URLs, and basic text formatting.

What is HTTP ?
Hypertext Transfer Protocol. The Internet protocol used to retrieve hypertext objects from remote hosts. HTTP messages consist of requests from client to server and responses from server to client.

What is HTTPS ?
HTTP layered over the SSL protocol.

What is IDL ?
Interface Definition Language. A language used to define interfaces to remote CORBA objects. The interfaces are independent of operating systems and programming languages.

What is IIOP ?
Internet Inter-ORB Protocol. A protocol used for communication between CORBA object request brokers.

What is impersonation ?
An act whereby one entity assumes the identity and privileges of another entity without restrictions and without any indication visible to the recipients of the impersonator's calls that delegation has taken place. Impersonation is a case of simple delegation.

What is initialization parameter ?
A parameter that initializes the context associated with a servlet.

What is ISO 3166 ?
The international standard for country codes maintained by the International Organization for Standardization (ISO).

What is ISV ?
Independent software vendor.

What is J2EE ?
Java 2 Platform, Enterprise Edition.

What is J2EE application ?
Any deployable unit of J2EE functionality. This can be a single J2EE module or a group of modules packaged into an EAR file along with a J2EE application deployment descriptor. J2EE applications are typically engineered to be distributed across multiple computing tiers.

What is J2EE component ?
A self-contained functional software unit supported by a container and configurable at deployment time. The J2EE specification defines the following J2EE components: Application clients and applets are components that run on the client. Java servlet and JavaServer Pages (JSP) technology components are Web components that run on the server. Enterprise JavaBeans (EJB) components (enterprise beans) are business components that run on the server. J2EE components are written in the Java programming language and are compiled in the same way as any program in the language. The difference between J2EE components and "standard" Java classes is that J2EE components are assembled into a J2EE application, verified to be well formed and in compliance with the J2EE specification, and deployed to production, where they are run and managed by the J2EE server or client container.

What is J2EE module ?
A software unit that consists of one or more J2EE components of the same container type and one deployment descriptor of that type. There are four types of modules: EJB, Web, application client, and resource adapter. Modules can be deployed as stand-alone units or can be assembled into a J2EE application.

What is J2EE product ?
An implementation that conforms to the J2EE platform specification.

What is J2EE product provider ?
A vendor that supplies a J2EE product.

What is J2EE server ?
The runtime portion of a J2EE product. A J2EE server provides EJB or Web containers or both.

J2EE Interview Questions and Answers 9

What is J2ME ?
Abbreviate of Java 2 Platform, Micro Edition.

What is J2SE ?
Abbreviate of Java 2 Platform, Standard Edition.

What is JAR ?
Java archive. A platform-independent file format that permits many files to be aggregated into one file.

What is Java 2 Platform, Enterprise Edition (J2EE) ?
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.

What is Java 2 Platform, Micro Edition (J2ME) ?
A highly optimized Java runtime environment targeting a wide range of consumer products, including pagers, cellular phones, screen phones, digital set-top boxes, and car navigation systems.

What is Java 2 Platform, Standard Edition (J2SE) ?
The core Java technology platform.

What is Java API for XML Processing (JAXP) ?
An API for processing XML documents. JAXP leverages the parser standards SAX and DOM so that you can choose to parse your data as a stream of events or to build a tree-structured representation of it. JAXP supports the XSLT standard, giving you control over the presentation of the data and enabling you to convert the data to other XML documents or to other formats, such as HTML. JAXP provides namespace support, allowing you to work with schema that might otherwise have naming conflicts.

What is Java API for XML Registries (JAXR) ?
An API for accessing various kinds of XML registries.

What is Java API for XML-based RPC (JAX-RPC) ?
An API for building Web services and clients that use remote procedure calls and XML.

What is Java IDL ?
A technology that provides CORBA interoperability and connectivity capabilities for the J2EE platform. These capabilities enable J2EE applications to invoke operations on remote network services using the Object Management Group IDL and IIOP.

What is Java Message Service (JMS) ?
An API for invoking operations on enterprise messaging systems.

What is Java Naming and Directory Interface (JNDI) ?
An API that provides naming and directory functionality.

What is Java Secure Socket Extension (JSSE) ?
A set of packages that enable secure Internet communications.

What is Java Transaction API (JTA) ?
An API that allows applications and J2EE servers to access transactions.

What is Java Transaction Service (JTS) ?
Specifies the implementation of a transaction manager that supports JTA and implements the Java mapping of the Object Management Group Object Transaction Service 1.1 specification at the level below the API.

What is JavaBeans component ?
A Java class that can be manipulated by tools and composed into applications. A JavaBeans component must adhere to certain property and event interface conventions.

What is JavaMail ?
An API for sending and receiving email.

What is JavaServer Faces Technology ?
A framework for building server-side user interfaces for Web applications written in the Java programming language.

J2EE Interview Questions and Answers 10

What is JavaServer Faces conversion model ?
A mechanism for converting between string-based markup generated by JavaServer Faces UI components and server-side Java objects.

What is JavaServer Faces event and listener model ?
A mechanism for determining how events emitted by JavaServer Faces UI components are handled. This model is based on the JavaBeans component event and listener model.

What is JavaServer Faces expression language ?
A simple expression language used by a JavaServer Faces UI component tag attributes to bind the associated component to a bean property or to bind the associated component's value to a method or an external data source, such as a bean property. Unlike JSP EL expressions, JavaServer Faces EL expressions are evaluated by the JavaServer Faces implementation rather than by the Web container.

What is JavaServer Faces navigation model ?
A mechanism for defining the sequence in which pages in a JavaServer Faces application are displayed.

What is JavaServer Faces UI component ?
A user interface control that outputs data to a client or allows a user to input data to a JavaServer Faces application.

What is JavaServer Faces UI component class ?
A JavaServer Faces class that defines the behavior and properties of a JavaServer Faces UI component.

What is JavaServer Faces validation model ?
A mechanism for validating the data a user inputs to a JavaServer Faces UI component.

What is JavaServer Pages (JSP) ?
An extensible Web technology that uses static data, JSP elements, and server-side Java objects to generate dynamic content for a client. Typically the static data is HTML or XML elements, and in many cases the client is a Web browser.

What is JavaServer Pages Standard Tag Library (JSTL) ?
A tag library that encapsulates core functionality common to many JSP applications. JSTL has support for common, structural tasks such as iteration and conditionals, tags for manipulating XML documents, internationalization and locale-specific formatting tags, SQL tags, and functions.

What is JAXR client ?
A client program that uses the JAXR API to access a business registry via a JAXR provider.

What is JAXR provider ?
An implementation of the JAXR API that provides access to a specific registry provider or to a class of registry providers that are based on a common specification.

What is JDBC ?
An JDBC for database-independent connectivity between the J2EE platform and a wide range of data sources.

What is JMS ?
Java Message Service.

What is JMS administered object ?
A preconfigured JMS object (a resource manager connection factory or a destination) created by an administrator for the use of JMS clients and placed in a JNDI namespace.

What is JMS application ?
One or more JMS clients that exchange messages.

What is JMS client ?
A Java language program that sends or receives messages.

What is JMS provider ?
A messaging system that implements the Java Message Service as well as other administrative and control functionality needed in a full-featured messaging product.