Active Server Pages (ASP), also known as Classic ASP or ASP Classic, was Microsoft’s first server-side script-engine for dynamically-generated web pages. Initially released as an add-on to Internet Information Services (IIS) via the Windows NT 4.0 Option Pack (ca 1998), it was subsequently included as a free component of Windows Server (since the initial release of Windows 2000 Server). ASP.NET has superseded ASP.
The active scripting engine’s support of the Component Object Model (COM) enables the development of functionality in ASP websites. Each object provides a related group of frequently-used functions and data attributes. ASP 2.0 provided six built-in objects: Application, ASPError, Request, Response, Server, and Session.
Session, for example, is a cookie-based session object that maintains the state of variables from page to page. Functionality is further extended by objects which, when instantiated, provide access to the environment of the web server; as an example
FileSystemObject (FSO) is used to create, read, update and delete files.
Web pages with the .asp file extension use ASP, although some web sites disguise their choice of scripting language for security purposes (e.g. still using the more common .htm or .html extension). Pages with the .aspx extension use compiled ASP.NET (based on Microsoft’s .NET Framework), which makes them faster and more robust than server-side scripting in ASP which is interpreted at run-time; however, many ASP.NET pages still include some ASP scripting. Such marked differences between ASP and ASP.NET have led to use of the terms Classic ASP or ASP Classic, which also implies some nostalgia for the simpler platform.
Programmers write most ASP pages using VBScript, but any other Active Scripting engine can be selected instead by using the @Language directive or the
<script runat="server"> syntax. JScript (Microsoft’s implementation of ECMAScript) is the other language that is usually available. PerlScript (a derivative of Perl) and others are available as third-party installable Active Scripting engines.