ESI dynamic cache technology

The content of any website is constantly updated and changed, but this does not mean that the content of this website is dynamic content. In fact, dynamic Content refers to the content that the user obtains each time they click the same link.ProgramGenerated, such as ASP and JSP, corresponds to the static content, which is generally composed of text, images, and multimedia. The static content remains unchanged when the user clicks the corresponding link each time. The latest technology to solve dynamic content caching is to design website content through ESI technology.

Working principle of ESI Technology

The dynamically generated content can bring rich and exciting pages to users. website developers can easily and flexibly control related content, but while enjoying these conveniences, it also increases the processing pressure on website databases and application servers. When the website's access volume increases, the investment in hardware and databases is huge. Even so, it may still cause serious page delays or even access failures.

The root cause of slow user access to dynamically generated content is that the dynamically generated content must go through a complex process. First, based on different user requests, user requests are distributed to the corresponding software module of the Application Server. The software module must determine the data to be extracted from the database through calculation, then extract the data from the database and send it to the user in the defined format. These lengthy processes slow user access and increase server load.

In the actual environment, a dynamic page may only contain a small amount of content that is frequently changed or personalized. for traditional cache servers, in order to ensure the timeliness of pages, however, the entire page cannot be cached due to a small amount of dynamic content on the page. Edge side include describes content fragments in webpages that can be accelerated or cannot be accelerated using simple markup language, each web page is divided into different small parts to assign different Cache control policies, the cache server can dynamically combine different parts of a page before sending the complete webpage to the user based on these policies. This control can effectively reduce the number of times the server captures the entire page. Instead, it only extracts a small number of uncacheable fragments from the original server. Therefore, it can effectively reduce the load on the original server, at the same time, it increases the response time of user access.

ESI is a simple identification language. developers can use it to mark content fragments so that the cache can be accelerated through the corresponding cache server. In addition, ESI also defines a set of content verification standards, which enables the original server to manage cached content on the cache server and improve the website's ability to control content. The CDN network can also use the cache server supporting ESI installed on nodes distributed across the country to provide CDN services for dynamic website content.