The cache manager works with two data structures, the primary and secondary caches. Various
data structures operate slightly differently and, often, some level of synchronization is
required when performing manipulations. To eliminate contention of the data cache, a second
one is created by the cache manager. It uses the second one to perform any management
operations (add, update, delete) and sets a Boolean flag to immediately put it into play. The
other cache can then be deleted or saved depending on the refresh strategy. For example, if
the database is designed with time-stamps on changing data, deleting the cache is somewhat
wasteful. There might be only five changes, and there is really no need to transfer all of the
other data. By selecting only the items that changed and updating those in memory cache,
updates can happen frequently and take effect more promptly with less resource churn.
One of the major undertakings for BluePages was the introduction of Web-based management
for key subsystems (Figure 3). The cache management is one example of these Web-based
management systems.
Figure 3. Data cache Web-based administration
Approaches to Bu ld ng H gh Performance Web Appl cat ons
Copyright ?© 2007, Idea Group Inc.
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