Advanced Java Interview Questions -16

Advanced Java Interview Questions -16
1.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.

2.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.

3.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.

4.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 < or reference one that is defined in the DTD. In the XML data, the reference could be to an entity that is defined in the local subset of the DTD or to an external XML file (an external entity). The DTD can also carve out a segment of DTD specifications and give it a name so that it can be reused (included) at multiple points in the DTD by defining a parameter entity.

5.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.

6.What is Extensible Markup Language ?


7.What is external entity ?

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

8.What is external subset ?

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

9.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.

10.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.

11.What is filter chain ?

A concatenation of XSLT transformations in which the output of one transformation becomes the input of the next.

12.What is finder method ?

A method defined in the Interview Questions – Home interface and invoked by a client to locate an entity bean.

13.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

14.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.

15.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.

16.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.

17.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.

18.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.

19.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.

20.What is Java 2 Platform, Standard Edition (J2SE) ?

The core Java technology platform.

21.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.

22.What is Java API for XML Registries (JAXR) ?

An API for accessing various kinds of XML registries.

23.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.

24.What is J2SE ?

Abbreviate of Java 2 Platform, Standard Edition.

25.What is JAR ?

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

26.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.

27.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.

28.What is Java Message Service (JMS) ?

An API for invoking operations on enterprise messaging systems.

29.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.

30.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.

31.What is JavaMail ?

An API for sending and receiving email.

32.What is JavaServer Faces Technology ?

A framework for building server-side user interfaces for Web applications written in the Java programming language

33.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.

34.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.

35.What is Java Transaction API (JTA) ?

An API that allows applications and J2EE servers to access transactions.

36.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.

37.What is JavaServer Faces UI component class ?

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

38.What is Java Naming and Directory Interface (JNDI) ?

An API that provides naming and directory functionality.

39.What is Java Secure Socket Extension (JSSE) ?

A set of packages that enable secure Internet communications.

40.What is JAXR client ?

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

41.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.

42.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.

43.What is JMS ?

Java Message Service.

44.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.

45.What is JMS application ?

One or more JMS clients that exchange messages.

46.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.

47.What is JDBC ?

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

48.What is JavaServer Faces validation model ?

A mechanism for validating the data a user inputs to a JavaServer Faces UI component.

49.What is JMS client ?

A Java language program that sends or receives messages.

50.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.

51.What is JSP expression ?

A scripting element that contains a valid scripting language expression that is evaluated, converted to a String, and placed into the implicit out object.

52.What is JSP expression language ?

A language used to write expressions that access the properties of JavaBeans components. EL expressions can be used in static text and in any standard or custom tag attribute that can accept an expression.

53.What is JSP standard action ?

An action that is defined in the JSP specification and is always available to a JSP page.

54.What is life cycle (JavaServer Faces) ?

A set of phases during which a request for a page is received, a UI component tree representing the page is processed, and a response is produced. During the phases of the life cycle: The local data of the components is updated with the values contained in the request parameters. Events generated by the components are processed. Validators and converters registered on the components are processed. The components’ local data is updated to back-end objects. The response is rendered to the client while the component state of the response is saved on the server for future requests.

55.What is JSP page ?

A text-based document containing static text and JSP elements that describes how to process a request to create a response. A JSP page is translated into and handles requests as a servlet.

56.What is JSP scripting element ?

A JSP declaration, scriptlet, or expression whose syntax is defined by the JSP specification and whose content is written according to the scripting language used in the JSP page. The JSP specification describes the syntax and semantics for the case where the language page attribute is “java”.

57.What is JSP scriptlet ?

A JSP scripting element containing any code fragment that is valid in the scripting language used in the JSP page. The JSP specification describes what is a valid scriptlet for the case where the language page attribute is “java”.

58.What is local subset ?

That part of the DTD that is defined within the current XML file.

59.What is managed bean creation facility ?

A mechanism for defining the characteristics of JavaBeans components used in a JavaServer Faces application.

60.What is JTA ?

Abbreviate of Java Transaction API.

61.What is JSP tag file ?

A source file containing a reusable fragment of JSP code that is translated into a tag handler when a JSP page is translated into a servlet.

62.What is JSP tag handler ?

A Java programming language object that implements the behavior of a custom tag.

63.What is JSP tag library ?

A collection of custom tags described via a tag library descriptor and Java classes.

64.What is JSTL ?

Abbreviate of JavaServer Pages Standard Tag Library.

65.What is JTS ?

Abbreviate of Java Transaction Service.

66.What is keystore ?

A file containing the keys and certificates used for authentication

67.What is life cycle (J2EE component) ?

The framework events of a J2EE component’s existence. Each type of component has defining events that mark its transition into states in which it has varying availability for use. For example, a servlet is created and has its init method called by its container before invocation of its service method by clients or other servlets that require its functionality. After the call of its init method, it has the data and readiness for its intended use. The servlet’s destroy method is called by its container before the ending of its existence so that processing associated with winding up can be done and resources can be released. The init and destroy methods in this example are callback methods. Similar considerations apply to the life cycle of all J2EE component types: enterprise beans, Web components (servlets or JSP pages), applets, and application clients.

68.what is message ?

In the Java Message Service, an asynchronous request, report, or event that is created, sent, and consumed by an enterprise application and not by a human. It contains vital information needed to coordinate enterprise applications, in the form of precisely formatted data that describes specific business actions.

69.What is message consumer ?

An object created by a JMS session that is used for receiving messages sent to a destination.

70.What is message-driven bean ?

An enterprise bean that is an asynchronous message consumer. A message-driven bean has no state for a specific client, but its instance variables can contain state across the handling of client messages, including an open database connection and an object reference to an EJB object. A client accesses a message-driven bean by sending messages to the destination for which the bean is a message listener.

71.What is message producer ?

An object created by a JMS session that is used for sending messages to a destination.

72.What is mixed-content model ?

A DTD specification that defines an element as containing a mixture of text and one more other elements. The specification must start with #PCDATA, followed by diverse elements, and must end with the “zero-or-more” asterisk symbol (*).

73.What is mutual authentication ?

An authentication mechanism employed by two parties for the purpose of proving each other’s identity to one another.

74.What is namespace ?

A standard that lets you specify a unique label for the set of element names defined by a DTD. A document using that DTD can be included in any other document without having a conflict between element names. The elements defined in your DTD are then uniquely identified so that, for example, the parser can tell when an element should be interpreted according to your DTD rather than using the definition for an element in a different DTD.

75.What is naming context ?

A set of associations between unique, atomic, people-friendly identifiers and objects.

76.What is parameter entity ?

An entity that consists of DTD specifications, as distinct from a general entity. A parameter entity defined in the DTD can then be referenced at other points, thereby eliminating the need to recode the definition at each location it is used.

77.What is parsed entity ?

A general entity that contains XML and therefore is parsed when inserted into the XML document, as opposed to an unparsed entity.

78.What is naming environment ?

A mechanism that allows a component to be customized without the need to access or change the component’s source code. A container implements the component’s naming environment and provides it to the component as a JNDI naming context. Each component names and accesses its environment entries using the java:comp/env JNDI context. The environment entries are declaratively specified in the component’s deployment descriptor.

79.What is normalization ?

The process of removing redundancy by modularizing, as with subroutines, and of removing superfluous differences by reducing them to a common denominator. For example, line endings from different systems are normalized by reducing them to a single new line, and multiple whitespace characters are normalized to one space.

80.What is North American Industry Classification System (NAICS) ?

A system for classifying business establishments based on the processes they use to produce goods or services.

81.What is notation ?

A mechanism for defining a data format for a non-XML document referenced as an unparsed entity. This is a holdover from SGML. A newer standard is to use MIME data types and namespaces to prevent naming conflicts.

82.What is method-binding expression ?

A Java Server Faces EL expression that refers to a method of a backing bean. This method performs either event handling, validation, or navigation processing for the UI component whose tag uses the method-binding expression.

83.What is method permission ?

An authorization rule that determines who is permitted to execute one or more enterprise bean methods.

84.What is OASIS ?

Organization for the Advancement of Structured Information Standards. A consortium that drives the development, convergence, and adoption of e-business standards.

85.What is OMG ?

Object Management Group. A consortium that produces and maintains computer industry specifications for interoperable enterprise applications.

86.What is one-way messaging ?

A method of transmitting messages without having to block until a response is received.

87.What is ORB ?

Object request broker. A library that enables CORBA objects to locate and communicate with one another.

88.What is OS principal ?

A principal native to the operating system on which the J2EE platform is executing.

89.What is OTS ?

Object Transaction Service. A definition of the interfaces that permit CORBA objects to participate in transactions.

90.What is parser ?

A module that reads in XML data from an input source and breaks it into chunks so that your program knows when it is working with a tag, an attribute, or element data. A nonvalidating parser ensures that the XML data is well formed but does not verify that it is valid. See also validating parser.

91.What is passivation ?

The process of transferring an enterprise bean from memory to secondary storage. See activation.

92.What is persistence ?

The protocol for transferring the state of an entity bean between its instance variables and an underlying database.

93.What is persistent field ?

A virtual field of an entity bean that has container-managed persistence; it is stored in a database.

94.What is primary key ?

An object that uniquely identifies an entity bean within a home.

95.What is principal ?

The identity assigned to a user as a result of authentication.

96.What is privilege ?

A security attribute that does not have the property of uniqueness and that can be shared by many principals.

97.What is POA ?

Portable Object Adapter. A CORBA standard for building server-side applications that are portable across heterogeneous ORBs.

98.What is point-to-point messaging system ?

A messaging system built on the concept of message queues. Each message is addressed to a specific queue; clients extract messages from the queues established to hold their messages.

99.What is processing instruction ?

Information contained in an XML structure that is intended to be interpreted by a specific application.

100.What is programmatic security ?

Security decisions that are made by security-aware applications. Programmatic security is useful when declarative security alone is not sufficient to express the security model of an application.

101.What is prolog ?

The part of an XML document that precedes the XML data. The prolog includes the declaration and an optional DTD.

102.What is public key certificate ?

Used in client-certificate authentication to enable the server, and optionally the client, to authenticate each other. The public key certificate is the digital equivalent of a passport. It is issued by a trusted organization, called a certificate authority, and provides identification for the bearer.

103.What is publish/subscribe messaging system ?

A messaging system in which clients address messages to a specific node in a content hierarchy, called a topic. Publishers and subscribers are generally anonymous and can dynamically publish or subscribe to the content hierarchy. The system takes care of distributing the messages arriving from a node’s multiple publishers to its multiple subscribers.

104.What is RAR ?

Resource Adapter Archive. A JAR archive that contains a resource adapter module.

105.What is RDF ?

Resource Description Framework. A standard for defining the kind of data that an XML file contains. Such information can help ensure semantic integrity-for example-by helping to make sure that a date is treated as a date rather than simply as text.

106.What is RDF schema ?

A standard for specifying consistency rules that apply to the specifications contained in an RDF.

107.What is realm ?

See security policy domain. Also, a string, passed as part of an HTTP request during basic authentication, that defines a protection space. The protected resources on a server can be partitioned into a set of protection spaces, each with its own authentication scheme or authorization database or both. In the J2EE server authentication service, a realm is a complete database of roles, users, and groups that identify valid users of a Web application or a set of Web applications.

108.What is reentrant entity bean ?

An entity bean that can handle multiple simultaneous, interleaved, or nested invocations that will not interfere with each other.

109.What is 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 < or reference one that is defined in the DTD. In the XML data, the reference could be to an entity that is defined in the local subset of the DTD or to an external XML file (an external entity). The DTD can also carve out a segment of DTD specifications and give it a name so that it can be reused (included) at multiple points in the DTD by defining a parameter entity.

110.What is query string ?

A component of an HTTP request URL that contains a set of parameters and values that affect the handling of the request.

111.What is queue ?

A messaging system built on the concept of message queues. Each message is addressed to a specific queue; clients extract messages from the queues established to hold their messages.

112.What is registry ?

An infrastructure that enables the building, deployment, and discovery of Web services. It is a neutral third party that facilitates dynamic and loosely coupled business-to-business (B2B) interactions.

113.What is remove method ?

Method defined in the Home interface and invoked by a client to destroy an enterprise bean.

114.What is render kit ?

A set of renderers that render output to a particular client. The JavaServer Faces implementation provides a standard HTML render kit, which is composed of renderers that can render HMTL markup.

115.What is registry provider ?

An implementation of a business registry that conforms to a specification for XML registries (for example, ebXML or UDDI).

116.What is relationship field ?

A virtual field of an entity bean having container-managed persistence; it identifies a related entity bean.

117.What is remote interface ?

One of two interfaces for an enterprise bean. The remote interface defines the business methods callable by a client.

118.What is renderer ?

A Java class that can render the output for a set of JavaServer Faces UI components.

119.What is resource adapter ?

A system-level software driver that is used by an EJB container or an application client to connect to an enterprise information system. A resource adapter typically is specific to an enterprise information system. It is available as a library and is used within the address space of the server or client using it. A resource adapter plugs in to a container. The application components deployed on the container then use the client API (exposed by the adapter) or tool-generated high-level abstractions to access the underlying enterprise information system. The resource adapter and EJB container collaborate to provide the underlying mechanisms-transactions, security, and connection pooling-for connectivity to the enterprise information system.

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