JavaBeans - Glossary

Activate

When a bean is read into a container from secondary storage and added to the working set, it is known as activation.

API

Application programming interface.

Atomic unit of work

A number of steps that must all be executed or none of them executed.

Bean factory

That part of an object monitor that is responsible for creating (manufacturing) the bean when required.

Bean handle

A universal reference to a bean instance, that is available from the EJBObject, that can be used to re-connect to a bean at a later time.

Bean interface

The interface that specifies the bean's business methods.

Begin transaction

Start a transaction. All steps that follow until either commit or rollback will be treated as an atomic unit of work.

Builder tool

A tool that allows the combining of client side JavaBeans into sophisticated applications with little or no programming.

Callback

A method in a bean that will be called by its container for some particular purpose.

Client

See client program.

Client program

A program that is written that uses the services of a remote object.

Commit transaction

Make the changes requested in the steps since the begin transaction permanent.

Component

A physical and replaceable part of a system that conforms to and provides a realization of a set of interfaces.

Concurrency

"In multi-threaded systems, an object that could have one or more threads executing its methods and changing its state at the same time is said to be concurrent and to exhibit concurrency."

Container

That part of a object monitor that manages the remote object and provides system services.

CORBA

The common object request broker architecture that allows clients to find servers and invoke their methods.

Deploy

Add a remote object to an Object Monitor so that it is available to clients.

Deployable unit

A deployable unit is a jar file for an EJB that contains the bean's class files and the DD used for software distribution.

Deployment descriptor

Information that describes both the structure of an Enterprise Java Bean, and the information required by it at runtime.

Design pattern

A generalized solution to a common frequently occurring object oriented design problem.

Distributed application

An application built from interacting remote objects.

Distributed object

An object somewhere on the network, that provides some service, that is known and available to clients.

Distributed system

A system made up of one or more applications that are built from interacting clients and remote objects.

Distributed transaction

If a transaction is started on a specific system and all requests to other remote objects maintain and propagate that transaction, the environment is said to support distributed transactions.

Download

Copy a file from a common resource to the local environment.

EJBObject

That skeleton of the bean that implements the bean's interface.

Entity bean

An EJB that is an object representation of a piece of persistent data.

Environment

The information that is part of the instance's context, used at runtime, that is set in the deployment descriptor and accessed through the EJBContext object.

Glossary

To access all the items in the course glossary, click the Show All Terms button below.

Handle

An object which contains all the information required to access an existing remote session bean.

Home interface

The Java interface that is implemented by the deployer to build the home object.

Home object

The EJB bean factory (see above). It listens on the network for client create() and remove() requests.

IIOP

The internet inter-orb protocol used by CORBA to communicate between CORBA clients and servers.

Implement

An object that provides a realization of a particular interface is said to implement that interface.

Instance

"An object. When a class is instantiated to produce an object, we say that the object is an instance of the class."

Instance's context

"Runtime information that is made available to the instance of the bean by the container. It includes security, transaction and environment information. "

Interface

The public methods of an object that provide some useful service.

J2EE

"Java 2 Enterprise Edition - includes EJBs, Servlets and Java Server Pages."

Jar file

A file created with the Java jar program which is similar to tar on the Unix platform.

Javadoc

The program that creates the HTML based documentation that is provided as part of the SDK.

JVM

The Java Virtual Machine, a software implementation of a portable environment, that executes Java programs.

Lifecycle

The states that an object can be in from its birth to its death.

Local resource

A resource, such as a database connection, that is accessible without traversing the network.

Lookup

The looking up of a service provided by the remote object in a name service.

Loopback

"When a bean, within and method, invokes its own methods, directly or indirectly it is known as a loopback."

Marshal

The translation of a method call with its parameters into a wire format suitable for transmission of a network transport. See un-marshalling.

Message

Another name for a method call. Conveys the idea that the method call is invoked across a network

Metadata

"The information about an object: its methods, parameters, return types, etc."

Middleware

Software systems and utilities that provide a service and sit between the client and backend databases or legacy systems.

Naming service

An entity that provides a lookup service to enable clients to find specific remote objects.

Network address

The information that is required to access the skeleton of a remote object somewhere on a remote host.

Network transport

Another name for a network and its associated protocols.

no-arg

A method that takes no arguments. For example create() in the home interface.

Object monitor

The combination of remote object together with the environment that manages it and that allows method calls to the remote object.

Object semantics

"The term implies that the objects have typical behavior as implemented in programming languages such as Java, C++ and SmallTalk."

Passivate

A container stores a bean on secondary storage to reduce its working set; this is known as passivation.

Persistence

Objects whose state lives beyond the lifetime of the object are known as persistent. The state is usually stored in a database.

Plumbing

A colloquial term for the set of system services that are available to a remote object.

Proxy pattern

A pattern, for implementing access to remote objects, that provides a local object having the same interface as the remote object.

Realization

The concrete implementation of one or more interfaces.

Remote interface

The Java interface that is used by the deployer to build the EJBObject.

Remote object

An object that provides a service through its methods and is located on another host on the network. The location of the object needs to be known before its methods can be called.

Remote reference

"The reference to an object, usually the stub, that knows where, and how to communicate with, a remote object."

RMI-IIOP

"The protocol, based on IIOP, that is planned for the implementation of RMI."

Rollback transaction

Undo any changes requested in the steps since the begin transaction.

Security

In this course security relates to client access to a remote object only.

Serializable (1)

The ability to convert from object semantics to a wire format.

Serializable (2)

"When multiple invocations of a method must be invoked one by one in sequence, this is known as serialization."

Server

That part of a object monitor that handles networking and distributed services.

Service

"To be useful, a remote object must perform some useful function. This function is know as the ""service"" it provides. "

Session bean

An EJB that has a 1 to 1 relationship with its client.

Skeleton

"The object that listens on the network for requests to a specific remote object from a client, then invokes those methods and returns any return value back to the client."

Stateful

The property of an object such that it contains information that is maintained across method calls.

Stateless

The property of an object such that it contains no information that needs to be preserved across method calls.

Stub

The object that the client uses to make requests of a remote object

Transaction

A transaction is a unit of work that comprises some input request, the processing of that request and the return of a response to the request.

Transaction aware

An environment that supports transactions.

Transaction management

Managing multiple operations in an object such that they all are executed or none are executed. This ensures consistent state of the underlying persistent information.

Transient

A label, applied to an instance variable of a bean, that instructs Java serialization to ignore that variable.

Transport

A transport network, or transportation network is a realisation of a spatial network, describing a structure which permits either vehicular movement or flow of some commodity.

Tuple

A expression that contains a pair of relate objects.

Un-marshaling

The translation of a method call back to object semantics from the wire format used to transmit it across the network.

Upload

Copy a class or a file to a common resource such as the name service.

VOIP

Voice over Internet Protocol (also called VoIP, IP Telephony, Internet telephony, and Digital Phone) is the routing of voice conversations over the Internet or any other IP-based network. The voice data flows over a general-purpose packet-switched network, instead of traditional dedicated, circuit-switched voice transmission lines.

Wire format

The format of a method call when translated into bytes suitable for sending over a network.

Working set

The number of beans a container can manage in memory concurrently.

XML

Extensible markup language; used to describe and transport information (data).