Introduction
To improve the performance of the online storefront, the template designer can direct the system to hold specific storefront pages in a cache.
The requested storefront page is retrieved from the cache without running the pipeline that invokes the template and generates the desired page. For more information about page caching and page caching restrictions, refer to the section Page Caching of the Application Programming Guide.
If you want a storefront page to be cached after the Java class file is generated in response to the first request for the template, you must invoke the <ISCACHE> tag in the template. The tag allows you to specify when the cached page should expire from the cache; after a fixed period of time or daily at a particular time.
The tag can be located anywhere in the template. See section Page Caching of the Application Programming Guide for a discussion on the interaction between page caching and ISML template inclusion.
Syntax
<iscache
type = "( relative | daily | forbidden )"
[ hour = "( {Integer} | {ISML expression} )" ]
[ minute = "( {Integer} | {ISML expression} )" ]
>
Note
Limited expiration date since 7.6.1.2
IMPORTANT: The cache expire time and date is set to the 19.1.2038 if the set hour and minutes values results in a later date. This is necessary to match the data type limitations of the Web Adapter. This limitation is introduced with version 7.6.1.2 and applies to later versions.
Note
When specifying time, the 24 hour clock is used. This means that 0 is equal to midnight, 1 is equal to 1 am, 2 is equal to 2 am, etc., up to 2359, which is equal to 11:59 pm.
Note
Publishing and visibility dates of the CMS are automatically evaluated and used to set cache expiration dates whenever CMS content is rendered in the storefront.
The caching on publishing and visibility dates will also happen if no caching behavior is set in ISML via <ISCACHE> tag.
In this regard it is important to know that not setting any <ISCACHE> tag is not the same as setting <ISCACHE type = "forbidden">. <ISCACHE type = "forbidden"> is not the default behavior, but if nothing else is set via <ISCACHE> tag or via CMS publishing and visibility dates, nothing will be cached. Setting <ISCACHE type = "forbidden"> explicitly in an ISML template will definitely disable all page caching where such an ISML template is used.
To summarize the default caching behavior is currently:
- No caching if no statement is done regarding caching
- CMS publishing and visibility dates are evaluated as a statement for caching until a specific expiration date
- the lowest of all caching statement times wins
<iscache type = "forbidden">is the "lowest" caching statement possible and will always win- BUT:
"forbidden"is not the default value if nothing is set!
In case the caching result produced by this default caching rules does not match the expected behavior, it is necessary to explicitly state the expected caching behavior in ISML.
Examples
A page based on a template that contains the following line of code would expire
from the cache after 90 minutes:
<ISCACHE type = "relative" hour = "1" minute = "30">
A page based on a template that contains the following line of code would expire
from the cache every day at 0630 hours (6:30 am):
<ISCACHE type = "daily" hour = "6" minute = "30">
A page based on a template that contains the following line of code would expire
from the cache every day at 2330 hours (11:30 pm):
<ISCACHE type = "daily" hour = "23" minute = "30">
A content component that has a publishing or visible date is always page cached, even if no <iscache> tag is used. Details are explained in a Note above. If page caching should be avoided in such case, explicitly set the <iscache> tag to "forbidden" in the related ISML template:
<ISCACHE type = "forbidden">
Attributes
type
The type attribute is required:
type = relative | daily | forbidden
relative allows you to specify a certain period of time, in minutes and hours, after which the page will be deleted from the cache.
daily allows you to specify a specific time when the page will be deleted from the cache.
forbidden allows you to explicitly exclude the template from being cached. This helps to make sure that no non-cacheable content is stored in the page cache even in complex ISML include structures.
Note
If multiple <ISCACHE> tags of the type daily or relative exist, the one with the shortest caching period takes precedence.
hour
This attribute is optional.
hour = integer
If the type attribute is set to daily, the hour value must be an integer ranging from 0 to 23. If type is set to relative, all integer values greater than or equal to 0 are valid (the default value is 0, meaning that either the page is never cached or only the minute attribute is relevant).
minute
This attribute is optional.
minute = integer
If the type attribute is set to daily, the minute value must be an integer ranging from 0 to 59. If type is set to relative, all integer values greater than or equal to 0 are valid (the default value is 0, meaning that either the page is never cached or only the hour attribute is relevant).