Asp. NET application extension policies

As a ASP.net performance advisor, the projects we touch are usually projects that have already been problematic. In many cases, call calls are made only after the application has been put into production. All the normal programs at the developer's are not working for the user. They complain: The site is too slow. Management wants to know why the problem was not found during the test. The development Department is unable to reproduce the problem. So some people say asp.net can not be extended. Does it sound familiar?

Some of the world's busiest WEB sites are running on asp.net. MySpace is a good example; in fact, it was run on a variety of platforms before being migrated to ASP.net. In fact, the performance problem may be manifested as the application continues to expand, and when this happens, you need to identify the actual problem that is occurring and find the best strategy to solve the problem. The biggest challenge you will face is to create a set of metrics that cover all aspects of your application's performance. If you do not consider the issue in its overall context, you will not know where to focus.

Performance equation

In September 2006, Peter Sevcik and Rebecca Wetzel of Netforecast published a paper entitled "Field Guide to Application Delivery". This paper deals specifically with how to improve the performance of wide area network (WAN) applications and includes the equation shown in Figure 1. This equation is for WAN performance, but it can be used to measure the performance of WEB applications with only a small amount of modification. The modified equation is shown in Figure 2, and the elements are explained in Figure 3.

Elements of the Figure 3 performance equation

Variable	Defined
R	Response time. The total amount of time that is required to render the entire page on the user's computer from the user Request page (by clicking a link, and so on). A unit of measurement usually measured in seconds.
Load	The total number of bytes sent to the browser, including tags and all resources (for example, CSS, JS, image files, and so on).
Bandwidth	The rate of transmission between browsers. This may be asymmetric, if a given page is generated from multiple sources, this can represent multiple speeds. Typically, a total value is added as a single bandwidth, in bytes per second.
Appturns	The number of resource files required for a given page. These resource files include CSS, JS, images, and so on, as well as any other files that the browser retrieves during page display. In this equation, the HTML page is computed separately by the appturns expression plus the round-trip time (RTT).
Rtt	The time required for a round trip, regardless of the bytes transferred. For the page itself, at least one RTT must be consumed per request. A unit of measurement usually measured in milliseconds.
Concurrent Requests	The number of requests for a resource file that the browser issued concurrently. By default, Internet Explorer performs two concurrent requests. This setting can be adjusted, but it is rarely done.
Cs	The calculated time on the server. This is the time it takes to run the code, retrieve data from the database, and synthesize the response to be sent to the browser. The unit of measurement is milliseconds.
Cc	The calculated time on the client. This is the time it takes for the browser to actually display HTML on the screen, execute JavaScript, implement CSS rules, and so on.

Figure 1 The Original performance equation

Figure 2 The Web Version of the performance equation