About Pagelet/Portlet Caching Strategies
Pagelet/portlet caching is controlled both by the programmer
and by the administrator who registers the pagelet/portlet in Oracle
WebCenter Interaction or Oracle WebCenter Ensemble. Each and every
pagelet/portlet needs a tailored caching strategy to fit its specific
functionality.
A pagelet/portlet's caching strategy should take all possibilities
into account and use the most efficient combination for its specific
functionality. A pagelet/portlet that takes too long to generate can
degrade the performance of every page that displays it. These questions
can help you determine the appropriate caching strategy:
- Will the content accessed by the pagelet/portlet change? How often?
- How time-critical is the content?
- What processes are involved in producing pagelet/portlet content?
How expensive are they in terms of server time and impact?
- Is the pagelet/portlet the only client with access to the back-end
application?
- Is the content different for specific users?
- Can users share cached content?
Determine how often pagelet/portlet content must be updated, dependent
on data update frequency and business needs. Find the longest time
interval between data refreshes that will not negatively affect the
validity of the content or the business goals of the pagelet/portlet.
Since caching is indexed on the settings used by a pagelet/portlet,
new content is always requested when settings change (assuming that
no cached content exists for that combination of settings).
There are two common situations in which you might mistakenly
decide that a pagelet/portlet cannot be cached:
- In-place refresh: You might think that caching would "break"
a pagelet/portlet that uses in-place refresh because the pagelet/portlet
would be redirected to the original (cached) content. This can be
avoided if a unique setting is updated on every action that causes
a redraw, effectively "flushing" the cache. (In-place refresh renews
the pagelet/portlet display by causing the browser to refresh the
portal page at a set interval.)
- Invisible preferences: If the content of the pagelet/portlet
is dependent on something other than preferences (for example, the
pagelet/portlet keys off the User ID to display a name or uses portal
security to filter a list), caching can still be implemented with
“invisible preferences” (in this case, User ID). As with in-place
refresh, invisible preferences are set solely for the purpose of creating
a different cache entry. They are set programmatically, without the
user’s knowledge.
For details on implementing caching, see the following topics:
