Best Practices for Configuring Your Middle Tier

Using Apache Cache Control for Static Content

To avoid sending unnecessary requests to the server each time a client requests a static content item, you can configure Apache HTTP Server to set cache time-out values for static content.

Typically, after a browser initially downloads a static resource from the HTTP server, the browser sends a conditional HTTP GET request each time the browser encounters that resource again. For example, when a browser first downloads a SAS Web Report Studio logo image, the browser stores a local copy of the image. For each subsequent page that references the logo, the browser requests that the image be sent again if the image has been modified since the previous download. This sequence occurs for every static element and can result in large numbers of HTTP requests. Because the static content for is not modified often, most of these requests are unnecessary.

When you specify a cache time-out for each static element, clients (browser, proxy, or server cache) can avoid sending unnecessary requests to the HTTP server in order to check the validity of the content. When the browser first accesses a static element, the browser stores that element locally for the duration of the time-out value that is configured. During this time, subsequent queries to the HTTP server are suppressed for that element. The browser resumes queries as appropriate when the time-out period elapses within the session.

You can configure Apache HTTP Server to set cache time-out values for static content. This is true whether Apache HTTP Server is configured to serve that static content or is merely a reverse proxy to your Web application server.

Top of Page