aching is an essential strategy for improving the performance of your applications, and ColdFusion offers much pre-packaged functionality to assist in this area, including a number of application server caching settings in the ColdFusion Administrator. ColdFusion also offers caching options directly through ColdFusion tags. For example, developers can use the <cfquery> tag's cachedAfter and cachedWithin settings to cache the results of database queries and the <cfcache> tag for its direct support of user-interface caching.
The <cfcache> tag is not without its limitations, however. It works very well when you want to cache a whole HTML page, but if you want to cache just part of a page, you are out of luck. The "page" is the smallest unit that <cfcache> can process. Such a restriction might be reasonable for simple applications, but almost any sophisticated application design uses some kind of templating system to assemble complex interfaces from a variety of individual ColdFusion scripts. As such, most modern application designs don't allow whole pages to be cached since to do so requires a single script to serve as the root point for the whole application.
Many ColdFusion frameworks, like the popular Fusebox or the newer Mach-II, require that all traffic go through the same ColdFusion script (usually named something like index.cfm). If you place a <cfcache> tag on this page, only the first page accessed ever gets displayed.
Luckily, it's quite easy to write a cache tag that can work with sections of pages, and this article describes a script that does just that. The tag is named CacheOMatic (click here to download it), so the first step is to create a file called CacheOMatic.cfm and save it to a directory where ColdFusion custom tags are stored (the paths indicated under the setting "Custom Tag Paths" in the ColdFusion Administrator, generally a default path that looks something like C:\CFusionMX\CustomTags).
When you want to cache a section of a page, you surround it with the tag
<cf_CacheOMatic>, as in:
Here's some stuff to cache!
While you want to support a plain vanilla version of the tag, you also will add some optional parameters. The CacheOMatic tag will take the three inputs shown in Table 1, all optional.
||The "Key" of the Cache
||The scope in which you want to store this data; corresponds with ColdFusion scopes:
||How long until the cache expires
|Table 1. Optional Inputs for CacheOMatic|