Entity Beans, Security and Transactions 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.

Application Server

A server side program that manages clients requests, EJBs, servlets, connections to databases and legacy systems, etc.

 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, 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.

Bean-managed

The enterprise java bean itself is responsible for storing and restoring its state to and from the database.

Begin transaction

Start a transaction. All steps that follow this until either the commit or rollback command 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 a particular purpose.

Client

See client program.

Client program

A program that uses the services of a remote object.

Commit transaction

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

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.

Container-managed persistence

The container that is managing the enterprise java bean is responsible for storing and restoring the bean's state.

CORBA

Common Object Request Broker Architecture. The architecture that allows clients to find servers and invoke their methods.

DD

Common abbreviation for the Deployment Descriptor.

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 deployment descriptor 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 on the network, that provides a 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

A transaction that is started on a specific system and all requests to other remote objects maintain and propagate that transaction.

Download

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

EJBObject

The 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.

Global transaction

A transaction that is propagated by the transaction manager to all the resources that are involved in the processing of that transaction.

Glossary

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

Handle

An object that 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.

Instances 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 a 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.

JDBC

Java database connectivity package that is used by Java programmers to access RDBMS's.

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

A bean, within a method, directly or indirectly invoking its own methods.

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 back-end 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.

OAD

See Object interaction diagram.

Object interaction diagram

A diagram in UML that illustrates the interaction between objects shown in a time-based manner.

Object monitor

The remote object and the environment which manages it and allows method calls to the remote object.

Object semantics

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

Passivate

A container storing a bean on secondary storage to reduce its working set.

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.

Primary key

The data in a persistent entity object that uniquely identifies that entity.

Proxy pattern

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

RDBMS

Relational Database Management System.

Realization

The concrete implementation of one or more interfaces.

Recoverable object

An object which can be involved in a transaction whose state can always be recovered or rolled forward and is never in an ambiguous state. Typically a database.

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

The ability to convert from object semantics to a wire format. When multiple invocations of a method must be invoked one-by-one, in sequence, this is also known as serialization.

Server

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

Service

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

Session bean

An EJB that has a one-to-one relationship with its client.

Single thread of control

A situation where there is only a single thread executing an enterprise java bean at any moment in time.

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.

SSL

Secure Socket Layer. A standard encription technique for the data in messages that pass over TCP/IP-based exchanges.

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.

Synchronization object

An object inside the container that is used by the transaction manager to synchronize the transaction with the instance.

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. Either all of the steps within the unit of work will be completed or none of them will.

Transaction aware

An environment that supports transactions.

Transaction control

A declaration in the deployment descriptor that specifies which transaction is required when a method is invoked on a bean instance.

Transaction management

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

Transaction Manager

The part of the distributed transaction system that controls, manages and sequences the transaction.

Transactional object

An object which can be involved in a transaction and affect its outcome, but does not contain any state that can be recovered or rolled forward.

Transient

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

Transport

See network transport.

Tuple

A expression that contains a pair of relate objects.

Two-phase commit

A two-phase commit is a mechanism by which the committing of a transaction that invloves multiple recoverable resources guarantees atomicity and an all or nothing result.

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.

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).