POLYMORPHISM
Generally, the ability to appear in many forms. In object-oriented programming, polymorphism refers to a programming language’s ability to process objects differently depending on their data type or class. More specifically, it is the ability to redefine methods for derived classes. For example, given a base class shape, polymorphism enables the programmer to define different circumference methods for any number of derived classes, such as circles, rectangles and triangles. No matter what shape an object is, applying the circumference method to it will return the correct results. Polymorphism is considered to be a requirement of any true object-oriented programming language (OOPL).
The type of polymorphism described above is sometimes called parametric polymorphism to distinguish it from another type of polymorphism called overloading.
NET WORK MANAGEMENT
Refers to the broad subject of managing computer networks. There exists a wide variety of software and hardware products that help network system administrators manage a network. Network management covers a wide area, including:
· Security: Ensuring that the network is protected from unauthorized users.
· Performance: Eliminating bottlenecks in the network.
· Reliability: Making sure the network is available to users and responding to hardware and software malfunctions.
ACTIVE WEB PAGE
1. A specification for a dynamically created Web page with a .ASP extension that utilizes ActiveX scripting — usually VB Script or Jscript code. When a browser requests an ASP page, the Web server generates a page with HTML code and sends it back to the browser. So ASP pages are similar to CGI scripts, but they enable Visual Basic programmers to work with familiar tools.
2. ASP also stands for Application Service Provider
VB SCRIPT
Short for Visual Basic Scripting Edition, a scripting language developed by Microsoft and supported by Microsoft’s Internet Explorer Web browser. VBScript is based on the Visual Basic programming language, but is much simpler. In many ways, it is similar to JavaScript. It enables Web authors to include interactive controls, such as buttons and scrollbars, on their Web pages.
VIRTUAL MACHINE
A self-contained operating environment that behaves as if it is a separate computer. For example, Java applets run in a Java virtual machine (VM) that has no access to the host operating system. This design has two advantages:
· System Independence: A Java application will run the same in any Java VM, regardless of the hardware and software underlying the system.
· Security: Because the VM has no contact with the operating system, there is little possibility of a Java program damaging other files or applications.
The second advantage, however, has a downside. Because programs running in a VM are separate from the operating system, they cannot take advantage of special operating system features.
JAVA BEANS
A specification developed by Sun Microsystems that defines how Java objects interact. An object that conforms to this specification is called a JavaBean, and is similar to an ActiveX control. It can be used by any application that understands the JavaBeans format.
The principal difference between ActiveX controls and JavaBeans are that ActiveX controls can be developed in any programming language but executed only on a Windows platform, whereas JavaBeans can be developed only in Java, but can run on any platform.
DATA TYPE
In programming, classification of a particular type of information. It is easy for humans to distinguish between different types of data. We can usually tell at a glance whether a number is a percentage, a time, or an amount of money. We do this through special symbols — %, :, and $ — that indicate the data’s type. Similarly, a computer uses special internal codes to keep track of the different types of data it processes.
Most programming languages require the programmer to declare the data type of every data object, and most database systems require the user to specify the type of each data field. The available data types vary from one programming language to another, and from one database application to another, but the following usually exist in one form or another:
· integer : In more common parlance, whole number; a number that has no fractional part.
· floating-point : A number with a decimal point. For example, 3 is an integer, but 3.5 is a floating-point number.
· character (text ): Readable text
ACTIVE XA
control using ActiveX technologies. An ActiveX control can be automatically downloaded and executed by a Web browser. ActiveX is not a programming language, but rather a set of rules for how applications should share information. Programmers can develop ActiveX controls in a variety of languages, including C, C++, Visual Basic, and Java.
An ActiveX control is similar to a Java applet. Unlike Java applets, however, ActiveX controls have full access to the Windows operating system. This gives them much more power than Java applets, but with this power comes a certain risk that the applet may damage software or data on your machine. To control this risk, Microsoft developed a registration system so that browsers can identify and authenticate an ActiveX control before downloading it. Another difference between Java applets and ActiveX controls is that Java applets can be written to run on all platforms, whereas ActiveX controls are currently limited to Windows environments.
Related to ActiveX is a scripting language called VBScript that enables Web authors to embed interactive elements in HTML documents. Just as JavaScript is similar to Java, so VBScript is similar to Visual Basic. Currently, Microsoft’s Web browser, Internet Explorer, supports Java, JavaScript, and ActiveX, whereas Netscape’s Navigator browsers support only Java and JavaScript, though plug-ins can enable support of VBScript and ActiveX.
BROWSER
Short for Web browser, a software application used to locate and display Web pages. The two most popular browsers are Netscape Navigator and Microsoft Internet Explorer. Both of these are graphical browsers, which means that they can display graphics as well as text. In addition, most modern browsers can present multimedia information, including sound and video, though they require plug-ins for some formats.
APPLICATION
A program or group of programs designed for end users. Software can be divided into two general classes: systems software and applications software. Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources.
In contrast, applications software (also called end-user programs) includes database programs, word processors, and spreadsheets. Figuratively speaking, applications software sits on top of systems software because it is unable to run without the operating system and system utilities.
Bibliography
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