This chapter introduces the next technology for providing dynamic and interactive web pages. ASP.NET takes ASP a step further to simplify the development process of web pages and enhance scalability of web applications. First, we review the conventional way of developing web applications using ASP to uncover some of the pitfalls that ASP.NET overcomes. We then discuss the benefits of ASP.NET and provide a high-level survey of the classes in the ASP.NET, such as control and page, as well as the complete syntax of ASP.NET Web Forms. To wrap up the chapter, we discuss the many aspects of ASP.NET development: how ASP.NET supports Web Services development, how to use custom server controls, and how session management has been improved to provide more scalable web solutions.
Microsoft Active Server Pages (ASP) is a server-side scripting technology enabling dynamic web pages. An ASP page contains HTML markup and server-side scripts that dynamically generate HTML content. The server-side scripts run when a request for the ASP page arrives at the web server. Inputs to the ASP page come from the client browsers through HTTP POST and GET methods. ASP provides an object model to simplify developers’ tasks. Besides using objects from the ASP object model, such as Application, Server, Request, Response, and Session, developers can also use any other COM components available on the server.
If you’ve already been developing web applications using ASP, you probably agree that it is very easy to end up with intertwined, possibly conflicting HTML markups and server-side scripts. The poor encapsulation model of ASP pages makes them difficult to manage and reuse. Attempts have been made to improve upon this model, including server-side include files and parameterized functions in scripts; however, these attempts come with trade-offs such as time, the management of a network of include files, the performance impact of having nested includes, as well as object ID and variable-scope management.
Developers that deal with cross-browser web applications also run into problems generating HTML according the client’s browser capability. Most of the time, we end up generating only the simplest HTML tags and client-side scripts, which can be understood by many browsers, and foregoing the features of the more advanced browsers. The resulting web application can be only as good as the worst browser it supports. Sometimes, we also attempt to generate different HTML markups for different browsers to take advantage of browser-specific features, resulting in much better client-side experience; however, this involves much more development time and effort.
Since scripting in ASP is available only to late-bound languages such as VBScript and JavaScript, type-safety is not an option. In addition, server-side scripts in ASP pages get reinterpreted each time the page is accessed, which is not ideal for performance.
Form-state maintenance in an ASP-based application is also labor intensive—developers must do everything manually, including reposting data, using hidden fields, and session variables. At times, web applications are configured to run in web farm environments where there is more than one web server available to the client. Maintaining session states becomes much harder in these scenario because it is not guaranteed that the client would return to the same server for the next request. Basically, the developers have to save states manually to SQL Server or other external storage.
While ASP is a great technology to build dynamic web pages, it has room for improvement. ASP.NET evolved from ASP and overcomes most, if not all, of its shortfalls.