J2EE Interview Questions and Answers 14

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.

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.

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.

What is passivation ?
The process of transferring an enterprise bean from memory to secondary storage. See activation.

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

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

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

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.

What is primary key ?
An object that uniquely identifies an entity bean within a home.

What is principal ?
The identity assigned to a user as a result of authentication.

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

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

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.

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

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.

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.

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.