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Wednesday, January 11, 2006

Adavance Java Interview Questions Part 3

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 EJB server provider ?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 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. 92. 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 <>94. 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 ?

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 home interface and invoked by a client to locate an entity bean.

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