Application Program Interface, a set of routines, protocols, and tools for building software applications.

Also called an appserver. A program that handles all application operations between users and an organization's backend business applications or databases. Application servers are typically used for complex transaction-based applications. To support high-end needs, an application server has to have built-in redundancy, monitors for high-availability, high-performance distributed application services and support for complex database access.

Data Definition Language is used to specify a database scheme as a set of definitions expressed in a DDL script. The basic idea is to hide implementation details of the database schemes from the users.

J2EE modules that comprise an application are assembled into a single application Enterprise Archive (EAR) file.

Java 2 Platform Enterprise Edition, a platform-independent, Java-centric environment from Sun for developing, building and deploying Web-based enterprise applications online.

A high-level programming language developed by Sun Microsystems. Java is an object-oriented language similar to C++, but simplified to eliminate language features that cause common programming errors. Java source code files (files with a

.java

extension) are compiled into a format called bytecode (files with a

.class

extension), which can then be executed by a Java interpreter.

Java Archive, a file format used to bundle all components required by a Java applet. JAR files simplify the downloading of applets since all the components

(.class

files, images, sounds, and the like) can be packaged into a single file. In addition, JAR supports data compression, which further decreases download times.

Java Naming and Directory Interface (JNDI). Allows Java-enabled applications to use a unified interface to multiple naming and directory services in the enterprise. Part of the Java Enterprise API set. JNDI works with other J2EE technologies to organize and locate components in a distributed computing environment.

Java Virtual Machine. An abstract computing machine, or virtual machine, JVM is a platform-independent programming language that converts Java bytecode into machine language and executes it.

Uniform Resource Locator, the global address of documents and other resources on the World Wide Web.

Java modules that comprise an application are assembled into a single application Web Archive (WAR) file.

A Web Server a computer that delivers (serves up) Web pages. Every Web server has an IP address and possibly a domain name. For example, if you enter the URL

http://www.pcwebopedia.com/index.html

in your browser, this sends a request to the server whose domain name is

pcwebopedia.com

. The server then fetches the page named

index.html

and sends it to your browser. That request can also cause complex logic to be executed and manage database access.

Extensible Markup Language, a specification developed by the W3C. XML is a pared-down version of SGML, designed especially for Web documents. It allows designers to create their own customized tags, enabling the definition, transmission, validation, and interpretation of data between applications and between organizations.