There are a number of striking differences between ASP.NET and ASP. For some of these differences the benefits will be immediately obvious. For others. We ll have to get used to new ways of thinking about dynamic web Pages. Among the changes are:
ASP.NET pages are complied not interpreted. A binary executable is compiled upon the first request to the page. This image is stored in an in-memory cache on the web server and subsequent request to this page use this executable to service the request.
The Framework provides a very clean separation of code from content. With ASP because the HTML is generated as the page is interpreted your page logic must be embedded into the page at the location where you want the HTML generated by this logic to be output. With ASP.NET no HTML is generated until all of the code in your page has finished executing. The entire task of HTML generation is done in the page s rendering step which uses the properties for all of us who consider script writing and HTML generation a poor substitute to sitting down and writing real code.
ASP.NET Framework maintains state for you. Do you ever have to post of the server to apply validation logic to a data entry HTML form? When there s a problem you must write code to repopulate every input on your HTML form. You must also execute script inline to add validation messages next to the fields that have errors. The resulting code is often a tangled mess. If the business logic changes that s a tough page to maintain. With the ASP.NET Framework this state maintenance is done for you. The fields maintain their value without a single line of code written by you. This applies not only to simple text inputs but also to SELECT lists check boxes radio buttons and other input types on your form. Built-in validation controls allow you to enforce your business logic by adding a single tag to your page and simply checking the Page. Is Valid property when it posts to the server.
ASP.NET runs events on the server. In ASP because of the amount of script that must be mixed with the HTML it s common to split a single functional area across several pages. One page may collect data from a user whereas another accepts the HTTP post and updates your relational data telling your user the result of the operation. Although its possible to put this functionality into a single ASP page you do so at the risk of needing to maintain a garbled mess of code over the long haul. Breaking these functions into separate pages causes the number of files in your web site to balloon. With ASP.NET you can set up server side event traps
ASP.NET provides a consistent event model. With ASP script is executed on the page in a top-down manner. Although it s possible to put your script within functions that you call from the page body there s no event model that fires at specific points in the lifecycle of your page. With ASP.NET this event model has been added. Most importantly there s an event fired whenever your page. With ASP.NET this event your page begins to load. This is very much like the from_Load event in VB. The page load event can be trapped in a script tag or from your code behind the page. This gives you a consistent model for setting up your output.
