What is ESI?

The full name of ESI is the Edge Side inclue, a technique for page-judgment caching. ESI is a data buffering/caching server that provides the technology and services to buffer/cache parts of a Web page, which is a fragment of a page. Technical specifications initiated by Oracle Company, Why is there a page fragment cache

For large websites, there are some static content in the pages of the website, and some of them are dynamic content, such as weather, the latest news and so on. Web site to improve performance the static content is cached on the front-end reverse proxy server, the ESI directive is sent to the server side and then returned to the browser after the content is merged by the reverse proxy server.

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The author obtains the following results through analysis, Varnish,squid. Where varnish is free, development source, and for ESI support is very good, is the author recommended the use of reverse proxy server, performance is very good.

Squid's support for ESI is limited, and of course it can fulfill the needs of most users.