J2EE Interview Questions and Answers 15

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.

What is RAR ?
Resource Adapter Archive. A JAR archive that contains a resource adapter module.

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.

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

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.

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

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 <>

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.

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

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

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

What is remove method ?
Method defined in the Home interface and invoked by a client to destroy an enterprise bean.

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.

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

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.