Content Caching (Dynamic)

Contents:

Dynamic Content Caching (Full Page Caching) is the process of running code once and saving the output on the server for reuse in a set time frame (Cache Lifetime). Each time the code is requested, performance is improved by using the already run output instead of generating the same output each time.

An additional performance boost can be gained by utilizing client-side caching for "full page" cached content. Client-side caching is transparently supported in most browsers, providing an additional improvement to your user's experience (the performance boost is obtained when the client's browser caches content for fast access in subsequent requests, only when the content changes will it be physically retrieved from the Web Server).

When Should Files be Cached?

Files should be cached when their content is stable and does not require frequent changes.

When Not to Cache Files?

Caching is not recommended for files that have constantly changing output. For example: clocks, timers and database queries. (See Caching Alternatives to find out how to apply Partial Page Caching).

How to Activate Caching

The following procedure describes how to activate and define global caching settings. The global caching settings determine if Caching in general will be activated or not.

Caching by default is enabled (set to "ON"). In order to view/change the setting:

1. Click the Performance tab.

2. Pick a server to configure.

3. Click the Settings tab.

The dynamic caching enabled settings status will be displayed. Next, define the default caching settings. These settings are applied to all cached files.

To prevent unnecessary memory use, caching has to be actively applied to either a selected file or directory.

The performance module provides three options for caching files:

• Through the File View

• Through the Performance Test Report

• Through the URL Tab

Caching Alternatives

Web pages that contain sections that continuously change can also be cached. This partial page caching solution can be accomplished through, applying caching APIs to portions of code that do not change. Partial Page Caching provides an intermediate solution for providing a partial performance boost that sustains the accuracy of changing content.  
To find out more about "Partial Page Caching" go to: Partial and Preemptive Page Caching.

Note:

Dynamic Content Caching can be deactivated from Performance | Settings and changing Dynamic Caching Enabled to Off. This will remove all Dynamic Content Caching settings from the files on the server.
Partial Page Caching will not be affected and can be disabled by, removing the Caching APIs from the code. The Partial Page Caching APIs will be deprecated in the next release and are replaced by the Zend _Cache API (List of deprecated functions).  
Caching using the Zend_Cache APi can be disabled by setting "caching enabled" to "Off" from the GUI: Performance | Setting | Partial Caching section or by setting the directive: zend_cache.enabled = 0 in the zend.ini.