WHAT IS ASP?

            Active Server Page or ASP, as it is more commonly known, is a technology that enables you to make dynamic and interactive Web pages. ASP uses server-side scripting to dynamically produce web pages that are not affected by the type of browser the web site visitor is using.

            The default scripting language used for writing ASP is VBScripts; although you can use other scripting languages like JScript which is Microsoft’s version of Java Script. ASP pages have the extension .asp instead of .htm. When a page with the extension .asp is requested by a browser the web server interprets any ASP contained within the web page before sending the HTML produced to the browser. In this way all the ASP is run on the web server and no ASP will ever be passed to the web browser.

            Any web pages containing ASP cannot be run by just simply opening the page in web browser. Web pages that contain ASP must be requested through a web server that supports ASP. If there is no Web server, then ASP pages cannot be displayed. ASP was first introduced by Microsoft on its web server Internet Information Server (IIS) that runs on Windows 2000/XP Pro/NT4/95. ASP pages run best on this Web server. The micro version of this server is called Personal Web Server (PWS). Both IIS and RWS are available free of cost with Windows.

You can locate these Web servers in the following places:

            Windows 2000/XP Pro-IIS can be found in ‘add/Remove Programs’ in the ‘Control Panel’. Windows 98 – PWS can be found under ‘add-ons’ on the Windows 98 CD. Windows NT4/95-you can get hold of IIS by downloading the  NT4 Option Pack from Microsoft (don’t be fooled by the name as it also runs on Windows XP Home Edition – IIS and PWS are not supported on this operating system.

WHAT IS VB SCRIPT?

            Like Java Script, VB Script you to embed commands into an HTML document. When a user of compatible Web browser downloads your page, your VB Script commands are loaded by the Web browser along with the rest of the document. The commands are run in response to a series of events. VB Script is an interpreted language. The browser interprets the VB Script commands when they are loaded and run. They do not need to be compiled into an executable form by the Web author who uses them.

            VB Script is a fast flexible subset of Microsoft’s Visual Basic and Visual Basic for Applications Languages. VB Script is designed to be easy to program in and quick in adding active content to HTML documents. The language elements are mainly ones that will be familiar to anyone who has programmed in just about any language, such as If…Then…Else blocks and Do, While, and For…Next loops, and atypical assortment of operators and built-in functions.

What Can VB Script Do?

            VB Script provides a fairly complete set of built-in functions and commands. These function and commands allow you to perform math calculations, manipulate strings, play sounds, open up new windows and new windows and new windows and new URLs, and access and verify user input to your Web forms. The code to perform these actions can be embedded in a page and executed when the page is loaded. You can also write functions that contain code that is triggered by events you specify. For example, you can write a VB Script method that is called when the user clicks the Submit button of a form, or one that is activated when the user clicks a hyperlink on the active page.

            VB Script can also set the attributes or properties of ActiveX Controls, Java applets, and other objects present in the browser. This way, you can change the behavior of plug-ins or other objects without having to rewrite them. For example, your VB Script code could automatically set the text of an ActiveX label control based on what time the page is viewed.

WHAT IS JAVASCRIPT?

            JavaScript is a script is a script language from Netscape that is supported in Netscape Navigator as of Version 2.0. It is easier to use than Java, but not as powerful. JavaScript uses the HTML page as its user interface, whereas Java can generate a completely custom interface. On the client, JavaScript applets are maintained in source code. On the server, they are compiled into byte code, similar to Java programs. A JavaScript applet can be used to display a data entry form and validate the input, while a java program processes the information. JavaScript is also used to tie Java applets together.

            JavaScript evolved from evolved from Netscape’s Live Script language and was made more compatible with Java. Although it shares many of the features and structures of the full Java language, it was developed independently. JavaScript is endorsed by a number of software companies and is an open language that anyone can use without purchasing a license. It is supported by recent browsers from Netscape and Microsoft, though Internet Explorer only a subset, which Microsoft calls Jscript.

WHAT IS JAVA

            Java is language developed by Sun Microsystems which allows World Wide Web pages to contain code that is executed on the browser. Because Java is based on a single “virtual machine” that all implementations of java emulate, it is possible for Java programs to run on any system which has a version of java. It is also possible for Java programs to run on any system which has a version of Java. It is also possible for the “virtual machine” emulator to make sure that Java programs downloaded through the web do not attempt to do unauthorized things. Java is a full-blown object-oriented programming language developed by Sum Microsystems Inc. Java is an interpreted language. This means that in order for a java program to run on a computer, a run-time system (interpreter) will need to have been installed on the computer.

            The dynamism and interactivity is achieved by including links within an HTML page to Java programs called applets. When the link is clicked on, the Java applet is transferred to your computer and executed locally by the browser. Java will therefore eliminate the need for a client computer on the Internet to depend on the host computer for the execution of dynamic content.

Not only is Java poised to make the end user’s life more interesting, but it also provides a powerful programming environment for the software developer and Internet content provider.

            The Internet is a highly heterogeneous networked environment encompassing dozens of operating systems (Windows, Unix, Macintosh, OS/2, etc., etc.) running on a wide variety of microprocessors. A Java program once developed is capable of running on EVERY platform which has the Java interpreter. The implication of this portability is quite profound to the Internet programmer. The programmer no longer has to worry about developing different versions of an application to cater for the different computer platforms in use across the Internet. By programming in Java, only one application will need to be developed; it will then run on ALL platforms to which the Java interpreter is ported. In order to use Java applets, you need to have associate files, which are complied applet programs usually ending with class. One applet may need one or more .class files to make it work. You can check with the sources where you obtain the applets what .class files you need.