Question from the Symfony 2 test

Calling the render_esi function is not useful when ESI is enabled in the application configuration.

The render_esi function does not provide any other advantage than making it easier to write an ESI tag: it is exactly equivalent to writing the ESI tag directly in the template yourself.

The render_esi function will not display anything if there is no cache gateway that supports ESI tags.

In this example, the render_esi function caches the template for 5 minutes.

The render_esi function can either generate an ESI tag or embed the content corresponding to the controller rendering: this depends on the cache system present.