Glossary

abort

An operation to terminate a transaction in such a way that the values assigned to all protected resources are unchanged from the beginning of the transaction.

Access Control List (ACL)

The methods by which interactions with resources are limited to collections of users or programs for the purpose of enforcing integrity, confidentiality, or availability constraints.

ACID properties

The acronym for the four properties guaranteed by transactions: atomicity, consistency, isolation, and durability.

activation

The process of transferring an enterprise bean from secondary storage to memory.

See also [passivation]

adapter

A software component that provides an interface from the enterprise application to an enterprise information system (EIS), such as database or legacy system.

applet

A Java program that can be downloaded over the network and executed by a browser. In contrast to Java applications, which are loaded from a disk and running on an operating system shell, Java applets are programs that are loaded from a Web site to run on a Web browser.

applet container

A container that includes support for the applet programming model, such as a Web browser.

application assembler

An EJB role that composes components and modules into larger deployable application units.

application client

A client-tier component that executes in its own Java Virtual Machine. Application clients have access to some J2EE platform APIs (JNDI, JDBC, RMI/IIOP, JMS).

application client container

A container that supports application clients and provides a federated view of the J2EE platform APIs.

application client module

A software unit that consists of one or more classes and an application client deployment descriptor.

application component

A server-side component, such as an EJB, JSP, or servlet, that is deployed, managed, and executed on an application server. It can also be a client-side component such as a Java applet.

Application Programming Interface (API)

A set of classes and interfaces that specify a particular functionality; for example, the JDBC API.

application server

A server that shares and processes application logic and connections to back-end resources. It provides infrastructure with common services to access resources such as databases, ERP applications, and traditional mainframe applications. It also provides a mechanism to deploy J2EE applications.

asynchronous

An event that occurs at a time that is unrelated to the time at which another event occurs. The relationship between the times at which they occur is unpredictable.

atomicity

A property of a transaction in which all changes made to a database are made permanent; otherwise, all changes are rolled back.

authentication

The process used by a server to verify the identity of an entity, such as a user, a process, or a computer.

authorization

The process of determining which services may be accessed by a particular entity, such as a user, a process, or a computer, and giving that entity permission to access those services.

base class

A class from which other classes or beans are derived. A base class may itself be derived from another base class.

bean-managed persistence (BMP)

A relationship in which the transfer of data between an entity bean instance's variables and the underlying resource manager is managed by the entity bean.

bean-managed transaction (BMT)

A transaction in which an Enterprise JavaBean (EJB) controls the transaction boundaries. In a bean-managed transaction, controls can be specified using JTA.

Binary Large Object (BLOB)

An advanced SQL data type, which is part of SQL-3.

browser

An Internet-based tool that enables users to browse Web sites.

business logic

The code that implements the functionality of an application. In the EJB architecture, this logic is implemented by the methods of an EJB.

business method

A method of an EJB that implements the business logic of an application. Usually defined in the component interface and implemented by the bean class of an EJB.

bytecode

The compiled format for Java programs that can be run (interpreted) on any computer with a Java virtual machine (JVM).

callback method

The method in a component called by the container to notify the component of important events in its life cycle.

caller principal

A principal that is associated with an application component instance during a method invocation. For example, an EJB instance can call the getCallerPrincipal() method to get the principal associated with the current security context.

certificate

A digital statement that associates a particular public key with a name or other attributes. The statement is digitally signed by a certificate authority (CA).

certificate authority (CA)

A well-known and trusted entity that issues public key certificates. A certificate authority attests to a user's real-world identity, somewhat like a notary public.

Character Large Object (CLOB)

An advanced SQL data type that is part of SQL-3.

cipher

In cryptography, a coding system used to create encrypted messages.

cipher text

In cryptography, text that is encrypted.

class

A category of objects used in object-oriented programming. A class defines instances and class variables and methods, and specifies the interfaces and class implementations and the immediate super class of the class.

class hierarchy

The relationships between classes that share a single inheritance. All Java classes inherit from the Object class.

class method

A method that is invoked without reference to a particular object. Class methods affect the class as a whole, not a particular instance of the class. Also called a static method.

class variable

A data item associated with a particular class as a whole—not with particular instances of the class. Also called a static field.

CLASSPATH

An environmental variable that tells the Java virtual machine where to find the class libraries, including user-defined class libraries.

client

A process that remotely accesses resources of a server, which has larger computing power and memory capacity.

client certificate authentication

An authentication mechanism in which a client uses an X.509 certificate to establish its identity.

client/server

The model of interaction in distributed data processing in which a program at one location sends a request to a program at another location and awaits a response. The requesting program is called the client, and the responding program is called the server.

client-side program

A Java program, usually embedded in an HTML page and viewed with a Web browser.

cluster

A group of servers that work together to provide an application platform with more powerful and reliable services than a single server. A cluster appears to its clients as a single server but it is, in fact, a group of servers acting as one. Cluster includes both load-balancing and fail-over capabilities.

commit

The operation that ends a transaction and updates the database so that other processes can access any changes made.

Common Object Request Broker Architecture (CORBA)

A standard from the Object Management Group (OMG) for communicating between distributed objects. CORBA uses IDLs (interface definition languages) and ORBs (object request brokers), and communicates with IIOP (Internet Inter Operability Protocol).

compiler

A program to translate source code into code to be executed by a computer. The Java compiler translates source code written in Java into bytecode to run on the JVM.

component contract

The contract between a component and its container. The contract includes life cycle management of the component, a context interface that the instance uses to obtain various information and services from its container, and a list of services that every container must provide for its components.

components-off-the-shelf (COTS)

Components that are provided by EJB providers to be integrated or assembled together into enterprise applications.

concurrency

A concept that refers to multiple users or programs simultaneously sharing the same database. Transactions and locks are used to give each of these a consistent view of the database.

connection

A session with a database opened by a JDBC application program, so-called because it represents a connection between the program and a (usually remote) database. At any one time, only one transaction can be associated with a connection.

connector

A standard extension mechanism for containers to provide connectivity to enterprise information systems (EIS). A connector is specific to an EIS and consists of a resource adapter and application development tools for EIS connectivity.

consistency

A successful transaction transforms a database from a previous valid state to a new valid state.

constructor

A special class method that has the same name as the class and is used to construct and possibly initialize objects of its class type.

container

An entity that provides life cycle management, security, deployment, and runtime services to components. Each type of container (EJB, Web, JSP, servlet, applet, and application client) also provides component-specific services.

container-managed relationship (CMR)

A declarative relationship between an entity bean and another entity bean to map the join relationship of data records in a database.

container-managed persistence (CMP)

Data transfer between an entity bean's variables and a resource manager managed by the entity bean's container.

container-managed transaction (CMT)

A transaction whose boundaries are defined by an EJB container. An entity bean must use container-managed transactions.

conversational state

The set of all values of members of a session bean that can be stored by serializing the bean instance.

cookie

A piece of data that the server creates to store user information on the user's disk.

credentials

The information describing the security attributes of a principal, such as a password. Credentials can be acquired only through authentication or delegation.

cursor

A cursor is used to reference the current position in a result set of a SQL operation using JDBC connection.

Customer Information Control System (CICS)

An IBM-licensed program that enables transactions entered at remote terminals to be processed concurrently by user-written application programs.

data abstraction

A data type with a private representation and a public set of operations. The Java language uses the concept of classes to implement data abstraction.

data bean

A type of JavaBean component used to transfer data between the EJB tier and the Web tier. It's also a common design pattern called Value Object.

Data Definition Language (DDL)

A subset of SQL commands dealing with database objects. The most common DDL commands are CREATE TABLE and DROP TABLE.

Data Manipulation Language (DML)

A subset of SQL commands dealing with database objects. The most common DML commands are SELECT, DELETE, and UPDATE.

database

A collection of interrelated or independent data items stored together without redundancy to serve one or more applications.

database management system (DBMS)

A program or set of programs that enables users to structure and manipulate the data in the tables of a database. A DMBS ensures privacy, recovery, and integrity of data in a multiuser environment.

database system

A shorter term for a database management system (DBMS).

data type

A programming classification indicating the type of data in a variable. Some commonly used data types are various forms of integers, character, and Boolean.

deadlock

A condition that can occur when two or more users are waiting for each other to give up locks. Advanced DBMSs can detect deadlocks and abort one of the user transactions when this happens.

declaration

A statement that establishes an identifier and associates attributes with it, without necessarily reserving its storage (for data) or providing the implementation (for methods).

decryption

The process of taking cipher text (encrypted data) and a cryptographic key and producing plain text (the original unencrypted data).

default

The value of a variable assumed by a program if a value is not supplied by the user.

delegation

The act by which a specific principal authorizes another principal to use its identity or privileges. Such authorization can be granted with restrictions.

Denial of Service (DoS) attack

A security attack in which an organization's Web site is deprived of the services it offers, caused by an overwhelming false user requests. For example, an enterprise Web site could be forced to cease operation, thus causing the enterprise a great deal of time and money.

deployer

An EJB role that installs modules and J2EE applications into an operational environment.

deployment

The process of placing an application into a distributed environment and making the application available for use. Deployment can include such tasks as installation, configuration, and administration of various parts of the application.

deployment descriptor

An XML file provided with each J2EE module that describes all the runtime properties of components and how they should be deployed into a specific container. The deployment descriptor is processed by the application server's deployment tool before starting to deploy each component with its supplied parameters.

deprecation

Refers to an entity that is no longer recommended by the current specification, and it may no longer exist in a future release.

digital signature

A string of bits that is computed from the signed data and private key of an entity. A digital signature can be used to verify that the data came from the entity and was not modified in transit.

dirty read

A dirty read occurs when a transaction reads data from a database that has been modified by another transaction, and that data has not yet been committed.

distributed application

An application made up of distinct components running in separate runtime environments, usually on different platforms connected via a network. Typical distributed applications are two tier, three tier, and multitier.

distributed computing

An application design and implementation strategy that separates an application into units that are executed on different computers and communicate through a network. For example, an application can be separated into three distributed units: a user interface unit, a processing unit, and a storage unit.

distributed object

An object that can be located anywhere on a network. Distributed objects are packaged as independent units of code that can be accessed by remote clients via method invocations.

distributed transaction

Transactions that are demarcated and coordinated by an external transaction manager via the two-phase commit protocol across multiple resource managers. Also known as a global transaction.

distributed transaction processing (DTP)

A form of processing in which multiple application programs update multiple resources (such as databases) in a coordinated manner. Programs and resources can reside on one or more computers across a network.

document type definition (DTD)

A file that defines how the markup tags in SGML and XML documents should be interpreted by the application presenting the document.

domain

A collection of servers, services, interfaces, machines, and associated resource managers defined by a single configuration file.

double-byte character set (DBCS)

A set of characters in which each character is represented by two bytes, commonly called Unicode. Languages such as Japanese and Chinese, which contain more symbols than can be represented by 256 code points, require double-byte character sets. Compare with single-byte character set.

durability

Changes that a transaction makes to a database will survive future system or media failures.

EIS resource

An entity that provides EIS-specific functionality to its clients. Examples are a record or set of records in a database system, a business object in an ERP system, and a transaction program in a transaction processing system.

EJB container

A container that implements the EJB component contract of the J2EE architecture. This contract specifies a runtime environment for enterprise beans that includes security, concurrency, life cycle management, transaction, deployment, and other services. An EJB container is provided by an EJB or J2EE server.

EJB container provider

A vendor that supplies an EJB container.

EJB context

An object that allows an enterprise bean to invoke services provided by the container and to obtain the information about the caller of a client-invoked method.

EJB home object

An object that provides the life cycle operations (create, remove, find) for an enterprise bean.

EJB module

A software unit that consists of one or more enterprise beans and an EJB deployment descriptor.

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 the container's deployment tools.

EJB Query Language (EJB-QL)

A subset of SQL that is used to write declarative queries of a CMP's methods in the bean's deployment descriptor.

EJB server

Software that provides services to an EJB container. The J2EE architecture does not specify the contract between EJB server and container. An EJB server may host one or more EJB containers.

EJB server provider

A vendor that supplies the EJB server.

encapsulation

The hiding of a software object's internal representation. The object provides an interface that queries and manipulates the data without exposing its underlying structure.

encryption

The process of scrambling data to prevent unauthorized disclosure, while still preserving access to the original data by authorized users.

encryption key pair

An encryption key pair consists of the public key used to encrypt information and a private key used to decipher the information.

Enterprise Application Archive (EAR) file

A JAR archive that contains a J2EE application.

Enterprise Application Integration (EAI)

A concept in which all services, applications, and products in an enterprise can be integrated to work together.

enterprise applications

Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and secure.

enterprise bean provider

An application programmer who produces EJB classes, component and home interfaces, and deployment descriptor files, and packages them in an EJB .jar file.

enterprise information system (EIS)

The applications that comprise an enterprise's existing system for handling enterprise-wide information. These applications provide an information infrastructure for an enterprise. An EIS offers a well-defined set of services to its clients. Examples of EIS include enterprise resource planning (ERP) systems, mainframe transaction processing systems, and legacy database systems.

Enterprise JavaBeans (EJB)

A component architecture for the development and deployment of object-oriented, distributed, enterprise applications. Applications written using the Enterprise JavaBeans architecture are scalable, transactional, and secure.

enterprise resource planning (ERP)

A business management system that integrates all facets of the business, including planning, manufacturing, sales, and marketing.

entity bean

A type of EJB that represents persistent data maintained in a database. An entity bean can manage its own persistence or it can delegate this function to its container. An entity bean is transactional, and is identified by a primary key. The main two categories of an entity bean are BMP and CMP.

environment variable

A string of specific value that controls a certain attribute of an application. An environment variable is made available to the application as it starts.

exception

An event during program execution that prevents the program from continuing normally; generally, an error. The Java programming language supports exceptions with the try, catch, and throw keywords.

exception handler

A block of code that reacts to a specific type of exception. If the exception is for an error that the program can recover from, the program can resume executing after the exception handler has executed.

Extensible Markup Language

See [XML]

failover

The ability to transparently handle failure of a service invocation by handing the request off to another service provider.

firewall

A firewall monitors traffic between an internal network and the Internet and regulates the type of network traffic that can pass through it.

foreign key

A foreign key is an attribute of a table that is used to refer to rows of another table. The attribute value is the primary key value of the other table.

form-based authentication

An authentication mechanism in which a Web container provides an application-specific form for logging in.

garbage collection (GC)

The automatic detection and freeing of memory that is no longer in use. The Java runtime system performs garbage collection so that programmers never explicitly free objects.

global transaction

See [distributed transaction]

graphical user interface (GUI)

Refers to the techniques involved in using graphics, along with a keyboard and a mouse, to provide an easy-to-use interface to some program.

group

A set of users that share some characteristics. An ACL can assign permissions to a group, which are applied by default to each user of that group.

home handle

An object that can be used to obtain a reference of the EJB's home interface. A home handle can be serialized and stored to stable storage and deserialized to obtain the reference.

home interface

One of two interfaces (the home interface and the component interface) for an enterprise bean. The home interface defines zero or more methods for creating and removing an enterprise bean.

host

A computer that is attached to a network and provides services other than acting as a communication switch.

HTTPS

HTTP layered over the SSL protocol.

Hypertext Markup Language (HTML)

The basic language that is used to build hypertext documents on the World Wide Web. It is used in basic, plain ASCII-text documents, but when those documents are processed by a Web browser, the document can display formatted text, color, a variety of fonts, graphics images, special effects, hypertext jumps to other Internet locations, and information forms.

Hypertext Transfer Protocol (HTTP)

The Internet protocol, based on TCP/IP, used to fetch hypertext objects from remote hosts.

infrastructure

A set of hardware, software, components, and services that support enterprise computing and applications needs.

inheritance

A mechanism by which a class can use the attributes and methods defined in its base (super) classes.

instance method

Any method that is invoked with respect to an instance of a class. Also called simply a method.

See also [class method]

instance variable

A data item that is associated with a particular object. Each instance of a class has its own copy of the instance variables defined in the class.

See also [class variable]

integrated development environment (IDE)

A programming environment integrated into an application. Examples include JBuilder, Visual Age, and Visual Cafe.

integration

The ability of applications to share information or to process independently by requesting services and satisfying service requests. In a well-integrated system, all the parts have a purpose, and the parts combine effectively to achieve the purpose of the overall system.

interface

A set of methods defined (declared with its signatures) to be accessed by any class in the class hierarchy.

Interface Definition Language (IDL)

APIs written in Java that provide standards-based interoperability and connectivity with CORBA.

internationalization

The preparation of software for proper behavior in multiple locales and foreign languages.

Internet

A network of networks, consisting of literally millions of hosts around the world. This network uses the TCP family of protocols to communicate.

Internet Interoperability Protocol (IIOP)

The protocol used by CORBA clients to communicate with ORBs over the Internet.

Internet Protocol (IP)

One of the protocols in the TCP family. IP specifies the format of messages (called packets) and the addressing scheme.

interpreter

A module that alternately decodes and executes every statement in some body of code. The Java interpreter decodes and executes bytecode for the Java virtual machine.

See also [compiler]

intranet

A private network, inside a company or organization, that uses the same kinds of software that you would find on the public Internet.

invocation

The process of performing a method call on a distributed object, with or without knowledge of the object's location on the network.

IP multicast

A network protocol used in sending out data to distributed servers sharing one subnet. An unreliable packet delivery service supported by all operating systems and most routers, and used in clustering services.

isolation

Changes that a transaction makes to a database are not visible to other operations until the transaction completes its work.

isolation level

See [transaction isolation level]

J2EE application

Any deployable unit of J2EE functionality. This can be a single module or a group of modules packaged into an .ear file with a J2EE application deployment descriptor. J2EE applications are typically engineered to be distributed across multiple computing tiers.

J2EE architecture

Enterprise architecture, based on Java 2, that is used to develop, deploy, and manage enterprise applications. It provides a component-based framework, and infrastructure services through a set of unified APIs.

J2EE connector architecture (JCA)

An architecture for integration of J2EE products with enterprise information systems (EISs).

J2EE product provider

A vendor that supplies a J2EE product.

J2EE server

The runtime portion of a J2EE product. A J2EE server provides Web container and/or EJB container.

J2EE tool provider

An organization or software vendor that provides tools used for the development, packaging, and deployment of J2EE applications.

JAR Java Archive (JAR) file

A platform-independent file format that permits many files to be aggregated into one file.

Java

An object-oriented programming language developed by Sun Microsystems, Inc. A write-once, run-anywhere programming language.

Java 2 Platform, Enterprise Edition (J2EE platform)

An environment for developing and deploying enterprise applications. The J2EE platform consists of a set of services, application programming interfaces (APIs), and protocols that provide the functionality for developing multi-tiered, Web-based applications.

Java 2 Platform, Micro Edition (J2ME)

J2ME is the Java platform technology developed for consumer wireless devices.

Java 2 Platform, Standard Edition (J2SE platform)

The core Java technology platform.

Java API for XML Processing (JAXP)

A Java package that is used to parse XML documents in Java applications.

Java Authentication and Authorization Service (JAAS)

A Java package that enables services to authenticate and enforce the use of access controls upon users.

Java Database Connectivity (JDBC)

An industry standard for database-independent connectivity between the Java platform and a wide range of databases.

Java Development Kit (JDK)

A software development environment for writing applets and applications in the Java programming language.

Java Management Extensions (JMX)

Java standard API for application management.

Java Message Service (JMS)

The Java standard API used to access message-oriented middleware (MOM) by enterprise applications. Includes messaging products such as IBM's MQ Series.

Java Naming and Directory Interface (JNDI)

The Java standard API for accessing directory services, such as LDAP, COS Naming, and others.

Java Remote Method Invocation (RMI)

A distributed object model for Java program to Java program, in which the methods of remote objects written in the Java programming language can be invoked from other Java virtual machines, possibly on different hosts.

Java Runtime Environment (JRE)

A runtime version of the Java Development Kit (JDK) for end users and developers who want to redistribute only the runtime environment. It consists of the JVM, the Java core classes, and supporting files.

Java Security Manager

Works with the Java API to define security boundaries and enabling programmers to establish a custom security policy for their Java applications.

Java Transaction API (JTA)

A high-level application transaction interface and a Java mapping to XA. Allows an application to control user transaction boundaries through the use of the two-phase commit protocol.

Java Transaction Service (JTS)

Specifies the implementation of a transaction manager that supports JTA and implements the Java mapping of the OMG Object Transaction Service (OTS) 1.1 specification at the level below the API.

Java Virtual Machine (JVM)

A software execution engine that safely and compatibly executes the bytecodes in Java class files on a microprocessor (whether in a computer or in another electronic device).

Java Web Server

A secure, platform-independent HTTP server to speed and simplify the deployment and management of Internet and intranet Web sites.

JavaBean Activation Framework (JAF)

A Java package to support for MIME (Multipurpose Internet Mail Exchange) data types. It's required by the JavaMail API.

JavaBeans

JavaBeans is a portable, platform-independent component model written in Java.

Javadoc

A tool that generates API documentation in HTML format from comments in Java source code.

JavaMail

An API for sending and receiving email, used by Java applications.

JavaServer Pages (JSP)

An extensible Web technology that uses template data, custom elements, scripting languages, and server-side Java objects to return dynamic content to a client. Typically, the template data is HTML or XML elements; in many cases, the client is a Web browser.

JDBC driver

A Java program that implements the JDBC interface. It is loaded by the JDBC driver manager.

JDBC-ODBC bridge

General database connectivity through the ODBC client library, created as a joint project between Intersolve and JavaSoft. Allows Java connectivity to any relational database.

JMS queue

A simple data structure to send/receive asynchronous messages from one client to another.

See also [point-to-point]

JMS topic

A simple data structure to publish/subscribe asynchronous delivery of messages from one client to another.

See also [point-to-point]

JSP

See [JavaServer Pages]

JSP action

A JSP element that can act on implicit objects and other server-side objects or can define new scripting variables.

JSP application

A Web application, written using the JSP technology, that can contain JSP pages, servlets, HTML files, images, applets, and JavaBeans components.

JSP container

A container that provides the same services as a servlet container and an engine that interprets and processes JSP pages into a servlet.

JSP declaration

A JSP scripting element that declares methods, variables, or both, in a JSP file.

JSP directive

A JSP element that gives an instruction to the JSP container and is interpreted at translation time.

JSP element

A portion of a JSP page that is recognized by a JSP translator. An element can be a directive, an action, or a scripting element.

JSP expression

A scripting element that contains a valid scripting language expression that is evaluated, converted to a string, and placed into the implicit out object.

JSP file

A file named with a .jsp extension that contains standard HTML tags, core JSP tags, custom JSP tags, and scripting language statements in order to display dynamic pages in a Web browser.

JSP page

A text-based document using fixed template data and JSP elements that describes how to process a request to create a response.

JSP scripting element

A JSP declaration, scriptlet, or expression, whose tag syntax is defined by the JSP specification, and whose content is written according to the scripting language used in the JSP page.

JSP scriptlet

A JSP scripting element containing any code fragment that is valid in the scripting language used in the JSP page.

JSP tag

A piece of text between a left angle bracket and a right angle bracket that is used in a JSP file as part of a JSP element.

JSP tag library

A collection of tags identifying custom actions described via a tag library descriptor (TLD) and Java classes. It can be imported into any JSP file and used with various scripting languages.

just-in-time (JIT) compiler

A compiler that converts all the bytecode into native machine code just as a Java program is run. This results in run-time speed improvements over code that is interpreted by a Java virtual machine.

legacy application

An application, often internally developed, on which an organization has invested considerable time and money. Legacy applications may exist with many other similar legacy applications in a centralized environment. While most legacy applications run on mainframes; minicomputers and some large Unix systems can be considered legacy systems using internally developed legacy applications.

Lightweight Directory Access Protocol (LDAP)

A set of protocols for accessing information directories. These directories can be physically distributed across multiple systems for access by many applications within an enterprise. LDAP is based on the standards contained within the X.500 standard, but is significantly simpler.

load balancing

A mechanism to distribute processing and communications activity evenly across a computers sharing the same load. It is part of clustering technology offered by application server vendors.

local interface

One of two interfaces for an EJB. The local interface defines the business methods callable by a local client.

See also [remote interface]

local transaction

A transaction that accesses a single database or file and is controlled by a single, local resource manager as a transaction participant.

lock

Locks allow a database transaction to mark data (for example, rows or tables) it is using to exclude a concurrent user from performing certain operations on the same data.

man-in-the-middle attack

An attack in which an enemy inserts a machine into a network, and then captures, possibly modifies, and retransmits all messages between two parties.

message

A formula for sending data and values across applications. It consists of a header, containing message ID data, and a body containing user-defined information.

message-driven bean (MDB)

A type of EJB that handle asynchronous messages received from JMS destination. The message-driven bean selects an instance from a pool to process the message.

message-oriented middleware (MOM)

A product used to deliver asynchronous messages from one application to another.

metadata

Data about data. It describes, for example, the types of data in the database schema.

method

A procedure associated with a class or interface, defining one of the legal operations on instances of the class or interface.

method call

A communication from one object to another that requests the receiving object to execute a method. It consists of a method name that indicates the requested method and the arguments to be used in executing the method.

method permission

An authorization rule that determines who is permitted to execute one or more EJB methods. It can be specified in the EJB's deployment descriptor.

Model-View-Controller (MVC)

An architecture pattern that provides separation of application parts into more independent layers, which can be separately developed, and managed.

module

A software unit that consists of one or more J2EE components of the same container type and one deployment descriptor of that type.

multithreading

The ability of an operating system to execute different parts of an application, called threads, at the same time, allowing the application to perform multiple tasks simultaneously.

multitier

An application architecture that includes clients (one tier), middleware (one or more tiers), and brokers, application servers, and other kinds of resources suppliers (one or more tiers).

mutual authentication

An authentication mechanism employed by two parties for the purpose of proving each other's identity to one another.

name binding

The association of a name with an object reference. Name bindings are stored in a naming context.

naming context

A set of associations between distinct, atomic, human-readable identifiers and objects.

nonrepeatable read

Data returned by a SQL query that would be different if the query were repeated within the same transaction. Nonrepeatable reads can occur when other users are updating the same data you're reading.

object

The building blocks of object-oriented programs. An object is a programming unit consists of data (instance variables) and functionality (instance methods).

See also [class]

object request broker (ORB)

A CORBA term designating the means by which objects transparently make requests and receive responses from objects, whether they are local or remote.

Object Transaction Service (OTS)

A definition of the interfaces that permit CORBA objects to participate in transactions.

object-oriented programming (OOP)

A programming approach based on the concepts of data abstraction, inheritance, and polymorphism.

online transaction processing (OLTP)

A method of assuring the integrity of each database transaction, usually through a process called two-phase commit.

Open Database Connectivity (ODBC)

A Microsoft-developed C database API that allows access to database management systems using SQL.

open system

A system that implements specified common standards across different computer vendors. Implementing open system standards for communication allows computers from different vendors to communicate with each other.

operation

A method or service that can be requested of an object.

overloading

An object-oriented programming technique that allows redefinition of methods when the methods are used with class types.

overriding

Providing a different implementation of a method in a subclass of the class that originally defined the method.

package

A program element that contains related classes and interfaces.

parametric authorization

The ability to perform authorization decisions on protected resources taking the context and target of the business request into account.

parent class

Same as base class or super class.

passivation

The process of transferring an enterprise bean from memory to secondary storage.

See also [activation]

permission

Defines access to a system resource. In order to allow access to a resource, the corresponding permission must be explicitly granted to the principal attempting access. This is ability to carry out certain operations on certain objects, as defined in an access control list.

persistence

The protocol for transferring the state of an entity bean between its instance variables and an underlying data elements in a database.

phantom read

A condition occurs when your program fetches a record that has been inserted by another user's transaction, and the other transaction subsequently aborts, erasing the record you fetched.

platform

The combination of system hardware and software that supports an application.

plug-in

A software module that adds functionality to a larger application.

point-to-point (PTP)

A JMS messaging paradigm or model that send and receive asynchronous messages, which are exchanged through a queue.

See also [JMS queue]

portability

To transfer a program from one hardware or software environment to another by rewriting sections of the code that are machine dependent, and then recompiling the program on the new environment.

primary key

An attribute or set of attributes that are unique among rows of a table. A table's primary key is used to refer to rows of the table.

principal

The identity assigned to an entity as a result of authentication.

private key

An encryption/decryption key known only to the party or parties that exchange secure messages.

privilege

A security attribute that does not have the property of uniqueness and that may be shared by many principals.

process

A collection of code, data, and other system resources, including at least one thread of execution, that performs a data processing task.

protocol

A set of rules that govern the format and timing of messages sent and received over a communication link. For example, TCP/IP, RMI, and IIOP are protocols.

proxy

To transfer data processing tasks to another program or device.

proxy server

A proxy server sends requests to another server for processing, which is invisible to the end user.

pub/sub

A JMS messaging paradigm or model that publish and subscribe asynchronous messages, which are exchanged through a topic.

See also [JMS topic]

public key

A value provided by a certificate authority that, combined with a private key, can be used to encrypt and decrypt messages.

public key algorithm

An algorithm for encrypting or decrypting data with a public or private key. A private key is typically used to encrypt a message digest; in such an application, the public key algorithm is called a message digest encryption algorithm. A public key is typically used to encrypt a content-encryption key, or session key; in such an application, the public key algorithm called a key-encryption algorithm. An example of a public key algorithm is RSA.

query

A SQL SELECT statement.

realm

A domain for a set of security attributes. The realm organizes security information and defines its range of operations. A realm has its own idea of principals and permissions.

record

A row of a table or a row of the result set returned by a query. Also called tuple.

recovery

In transaction systems, after a failure, the ability to restore the system to the most recently committed, and therefore consistent, state.

re-entrant EJB

An enterprise bean that can handle multiple simultaneous, interleaved, or nested invocations that will not interfere with each other.

reference

A data element whose value is an address.

referential integrity

Correctness of foreign keys among table of a database. A DBMS maintains referential integrity by ensuring that there exists a row in the referenced table for every reference to the table.

relation

A table, the basic data structure of the relational model.

relational database management system (RDBMS)

DBMS for a relational database model.

reliability

The extent to which a system produces the correct output on repeated trials while meeting the performance requirement.

remote interface

One of two interfaces for an EJB. The remote interface defines the business methods callable by a remote client.

See also [local interface]

remote method invocation (RMI)

A technology that allows an object running in one Java virtual machine to invoke methods on an object running in a different Java virtual machine.

remote procedure call (RPC)

Executing what looks like a normal procedure call (or method invocation) by sending network packets to some remote host.

remove method

Method defined in the home interface and invoked by a client to destroy an enterprise bean.

resource adapter (RA)

A system-level software driver that is used by an EJB container or an application client to connect to an EIS. A resource adapter is typically specific to an EIS. It is available as a library and is used within the address space of the server or client using it.

Resource Adapter Archive (RAR)

A compressed .rar file used to load classes and other files required to run a resource adapter on a resource manager. An interface and associated software that provides access to a collection of information and processes; for example, a database management system.

resource manager

Provides access to a set of shared resources. A resource manager participates in transactions that are controlled and coordinated by a transaction manager. A resource manager is typically in different address space or on a different machine from the clients that access it.

resource manager connection

An object that represents a session with a resource manager.

resource manager connection factory

An object used for creating a resource manager connection.

RMI/IIOP

A version of RMI implemented to use the CORBA IIOP protocol. RMI over IIOP provides interoperability with CORBA objects.

role (development)

The function performed by a party in the development and deployment phases of an application developed using J2EE technology.

role (security)

An abstract logical grouping of users that is defined by the application assembler. When an application is deployed, the roles are mapped to security identities, such as principals or groups, in the operational environment.

role mapping

The process of associating the groups and/or principals recognized by the container to security roles specified in the deployment descriptor. Security roles have to be mapped by the deployer before the component is installed in the server.

rollback

The point in a transaction when all updates to any resources involved in the transaction are reversed.

scalability

The extent to which developers can apply a solution to problems of different sizes. Ideally, a solution should work well across the entire range of complexity. In practice, however, there are usually simpler solutions for problems of lower complexity.

schema

A description of the tables in a database, their attributes, and their relationships. Every database is an instance of some schema.

Secure Sockets Layer (SSL)

A protocol that allows communication between a Web browser and a server to be encrypted for privacy.

security attributes

A set of properties associated with a principal. Security attributes can be associated with a principal by an authentication protocol and/or by a J2EE product provider.

security context

An object that encapsulates the shared state information regarding security between two entities.

security permission

A mechanism, defined by J2SE, used by the J2EE platform to express the programming restrictions imposed on application component providers.

security policy

The data that defines what protection a system's security service must provide. There are many kinds of security policies. For example, access control policy and audit policy.

serialize

A way to pass objects from one JVM to another. Objects must be serialized before they are sent.

servlet

A server-side Java component that is usually executed in response to an HTTP request and produces its output in a browser.

servlet container

A container that provides the network services over which requests and responses are sent, decodes requests, and formats responses. All servlet containers must support HTTP as a protocol for requests and responses, but may also support additional request-response protocols, such as HTTPS.

servlet context

An object that contains a servlet's view of the Web application within which the servlet is running. Using the context, a servlet can log events, obtain URL references to resources, and set and store attributes that other servlets in the context can use.

session

An object used by a servlet to track a user's interaction with a Web application across multiple HTTP requests.

session bean

A session bean is a transient EJB instance that serves a single client. Session beans tend to implement procedural logic.

Simple API for XML (SAX)

An event-driven, serial-access mechanism for accessing XML documents.

Simple Object Access Protocol (SOAP)

SOAP provides a way for applications to communicate with each other over the Internet, independent of platform. Unlike OMG's IIOP, SOAP uses XML over HTTP in order to penetrate server firewalls. SOAP relies on XML to define the format of the information and then adds the necessary HTTP headers to send it.

single-byte character set

A set of characters in which each character is represented by a one-byte code, commonly called ASCII.

skeleton

A server-side representation of a remote object that takes serialized requests from a stub, deserializes and unpacks it, and submits it as a method call to be invoked on the object's implementation. The server-side skeleton is responsible for deserializing and unpacking the request from its companion client-side stub.

socket

A low-level endpoint of communication to which a name may be bound. The logical endpoint of a TCP/IP connection. An application accesses a TCP/IP connection through a socket.

SQL/J

A set of standards that includes specifications for embedding SQL statements in methods in the Java programming language and specifications for calling Java static methods as SQL stored procedures and user-defined functions.

SQL-93

The version of SQL standardized by ANSI in 1993. Sometimes called SQL-3.

stack trace

Java exceptions can be logged to a stack trace file that can be used for debugging.

Standardized Generalized Markup Language (SGML)

An ISO/ANSI/ECMA standard that specifies a way to annotate text documents with information about types of sections of a document.

stateful session bean

This Java bean maintains state on behalf of a specific client. It can be used to manage a process through multiple interactions.

stateless session bean

A session bean with no conversational state. All instances of a stateless session bean are identical.

stored procedure

A procedure that is part of a relational database.

Structured Query Language (SQL)

The standardized relational database language for defining database objects and manipulating data.

stub

A client-side representation of a remote object that is used to invoke methods on the implementation of the remote object. Defines the interface to the remote object implementation of an object. The stub is responsible for packaging up the client request, serializing it, and shipping it to the companion skeleton on the server side.

subclass

A class that is derived from a particular class, perhaps with one or more classes in between.

See also [base class]

See also [parent class]

See also [superclass]

subject

Represents a grouping of related information for a single entity, such as a person. Such information includes the subject's identities as well as its security-related attributes (for example, passwords and cryptographic keys). Subjects may potentially have multiple identities.

superclass

A class from which a particular class is derived, perhaps with one or more classes in between. See also subtype.

See also [subclass]

system administrator

An EJB role that is responsible for configuring and administering the enterprise's computers, networks, and software systems.

thin client

A system that runs a very light operating system with no local system administration and executes applications delivered over the network.

thread

The basic unit of program execution. A process can have several threads running concurrently, each performing a different job, such as waiting for events or performing a time-consuming job that the program doesn't need to complete before going on.

three-tier JDBC driver

A driver that implements the JDBC API by making calls to a middle-tier server that translates the calls into DBMS-specific protocols and makes the calls to the DBMS server.

throws

A Java programming language keyword used in method declarations that specify which exceptions are not handled within the method but rather passed to the next higher level of the program.

time-to-live (TTL)

An attribute of a JMS message that specifies how long the message will survive, before it expires, and then will be removed from the system.

transaction

A complete unit of work that transforms a database from one consistent state to another.

transaction attribute

A value specified in an EJB's deployment descriptor that is used by the EJB container to control the transaction scope when the enterprise bean's methods are invoked. A transaction attribute can have the following values: Required, RequiresNew, Supports, NotSupported, Mandatory, Never.

transaction isolation level

The degree to which the intermediate state of the data being modified by a transaction is visible to other concurrent transactions and data being modified by other transactions is visible to it.

transaction manager

Provides the services and management functions required to support transaction demarcation, transactional resource management, synchronization, and transaction context propagation, among different resource managers using XA two-phase commit protocol (2PC).

Transmission Control Protocol based on IP (TCP/IP)

This is an Internet protocol that provides for the reliable delivery of streams of data from one host to another.

See also [IP]

two-phase commit (2PC)

A method of coordinating a single transaction across more than one resource manager. 2PC guarantees data integrity by ensuring that transactional updates are committed in all the participating databases, or are fully rolled back out of all the databases, reverting to the state prior to the start of the transaction.

two-tier architecture

A client/server relationship in which the user interface runs on the client and the database is stored on the server. The actual application logic can run on either the client or the server.

two-tier JDBC driver

A JDBC driver that translates JDBC calls directly into a DBMS vendor's specific protocol.

Unicode

A 16-bit character encoding scheme used to display, process, and exchange text written in most of the world's languages. In Java, strings are Unicode by default.

Unified Modeling Language (UML)

A widely used notation for analysis, design, implementation, and test of object oriented software.

uniform resource identifier (URI)

A compact string of characters for identifying an abstract or physical resource. A URI is either a URL or a URN.

uniform resource locator (URL)

Used for identifying and locating resources over the Internet.

uniform resource name (URN)

A unique identifier that identifies an entity but doesn't tell where it is located. A system can use a URN to look up an entity locally before trying to find it on the Web.

unit of work (UOW)

Synonym of transaction.

Universal Description Discovery and Integration (UDDI)

Provides a global, public, XML-based, online business registry where businesses register and advertise their web services. UDDI defines an Internet version of the white and yellow pages in a telephone directory.

university registration system (URS)

Sample J2EE application provided on Day 21 of this book. Excerpts from URS are used to demonstrate the examples written for some lessons.

View bean

A type of JavaBean component used to transfer data between the Web tier and the Client tier.

warning

An exceptional condition that does not interrupt execution of an application program, such as truncation of data values. JDBC provides a getWarnings() method to obtain this information.

Web application

An application written for the Internet, including HTML, and those built with Java technologies such as JavaServer Pages and servlets.

Web Archive (WAR) file

A JAR archive that contains a Web module.

Web component

A component that provides services in response to requests; either a servlet, a JSP page, or a Tag Library.

Web container

A container that implements the Web component contract of the J2EE architecture. This contract specifies a runtime environment for Web components that includes security, concurrency, life cycle management, transaction, deployment, and other services.

Web module

A unit that consists of one or more Web components and a Web deployment descriptor.

Web server

Software that provides services to access the Internet, an intranet, or an extranet. A Web server hosts Web sites, provides support for HTTP and other protocols, and executes server-side programs (such as CGI scripts or servlets) that perform certain functions. In the J2EE architecture, a Web server provides services to a Web container.

Web Services

Loosely coupled software components capable of collaborating with each other over multiple networks to deliver a specific result to an end user. In the process, they leverage an emerging group of standards that govern their description and interaction, including SOAP (Simple Object Access Protocol), UDDI (Universal Discovery and Description Initiative), XML (Extensible Markup Language), and WSDL (Web Services Description Language).

Web Services Description Language (WSDL)

An XML-based specification to describe Web services.

World Wide Web (WWW)

The web of systems and the data in them that is the Internet.

See also [Internet]

X.509

A standard that specifies the format of certificates, which provide a way to securely associate a name to a public key, providing strong authentication.

XA interface

The XA interface is the bi-directional interface between a transaction manager and resource managers. The XA interface within JTA allows a transaction manager to control transaction boundaries for operations performed by multiple resource managers using the two-phase commit X/Open XA protocol.

XML (Extensible Markup Language)

A markup language that allows you to define the tags (markup) needed to identify the data and text in XML documents. J2EE deployment descriptors are expressed in XML.

XML schema

A document that defines valid contents for an XML document. A schema definition is more specific than a DTD, and provides much finer-grained control over content.