WHAT IS ASP / ASP.NET?

Given the complexity and sophistication of today’s Web technologies, it can be hard to remember that in its infancy the Internet was arguably a glorified file-transfer system. Clients would request (and hopefully receive) files from servers using established transfer protocols such as FTP and gopher. Eventually, these binary protocols gave way to the Hyper Text Markup Language (HTML) protocol, which allowed formatted text to be transferred across the Internet. Clients would still request files from servers, but the files would be dynamically rendered on a browser, which would format the HTML into readable content. The next step along the evolutionary ladder was the generation of dynamic content. Instead of providing clients with static files, servers would dynamically generate HTML files in response to a client’s requests. Two of the earliest frameworks were the Common Gateway Interface (CGI) and Microsoft Active Server Pages (ASP). These frameworks allowed for dynamic content creation in response to user actions. ASP.NET is Microsoft’s new version of ASP for the managed environment. ASP.NET brings about significant changes from its predecessor, most notably by supporting strongly typed and precompiled languages such as C# and VB. With ASP.NET you can also design web application GUIs using the drag-and-drop form design approach that made Visual Basic popular. ASP.NET is a server-side technology that requires the installation of Microsoft Internet Information Server (IIS). PROBLEMS WITH TRADITIONAL ASP ఇన్this section, we similarly examine the limitations of ASP in order to appreciate its evolved .NET manifestation. 1. ASP only supports scripting languages. ASP scripting code is usually written in languages such as JScript or Vb Script. Typically, these languages provide only a subset of the functionality exposed by a complete development language (such as Java or Visual Basic). Scripting languages such as JScript and VBScript are also weakly-typed. This means that all variables are Variants (generic types). Also, no type checking is done at design time, which often results in error prone code. The performance of ASP script code also suffers because it is interpreted. Unlike desktop applications that are fully compiled, ASP scripts are translated one line at a time by the ASP runtime, degrading performance. Interpreted scripting code also rises debugging issues. If line 50 of an ASP script contains a syntax error, it will not be caught until the previous 49 lines have executed. Modern development environments, in contrast, will catch all of a program’s syntax errors in a single compilation step. 2. Script Code is combined with the HTML interface. ASP files frequently combine script code with HTML. This results in ASP scripts that are lengthy, difficult to read, and switch frequently between code and HTML. The interspersion of HTML with ASP code is particularly problematic for larger web applications, where content must be kept separate from business logic. 3. COM Administration Because ASP only supports scripting languages; developers frequently move logic into COM components and then call them from ASP scripts. By writing COM components in languages such as C++, developers can leverage the strongly-typed features that are absent from ASP. Problems with the COM/ASP hybrid arise, however, when a COM component evolves and must be updated. Because the ASP.NET ASP runtime may keep objects loaded in memory, updating a COM component can require shutting down the web server (IIS) and possibly re-registering the component with the Windows Registry. This scenario is unacceptable for large, high traffic web applications where reliable service is paramount. 4. Application configuration is stored in a proprietary format that is not easily ported to different machines. The configuration information for an ASP web application (such as session state and server timeouts) is stored in the IIS metabase. Because the metabase is stored in a proprietary format, it can only be modified on the server machine with utilities such as the Internet Service Manager. With limited support for programmatically manipulating or extracting these settings, it is often an arduous task to port an ASP application from one server to another.