Product overview > Cache > Database integration
Side cache and in-line cache
WebSphere eXtreme Scale is used to provide in-line caching for a database back-end or as a side cache for a database. In-line caching uses eXtreme Scale as the primary means for interacting with the data. When eXtreme Scale is used as a side cache, the back-end is used in conjunction with the eXtreme Scale.
eXtreme Scale can be used as a side-cache for an application's data access layer. In this scenario, eXtreme Scale is used to temporarily store objects that would normally be retrieved from a back-end database. Applications check to see if eXtreme Scale contains the desired data. If the data is there, the data is returned to the caller. If the data is not there, the data is retrieved from the back-end and inserted into eXtreme Scale so that the next request can use the cached copy. The following diagram illustrates how eXtreme Scale can be used as a side-cache using an arbitrary data access layer such as OpenJPA or Hibernate.
Side cache plug-ins for Hibernate and OpenJPA
Figure 1. Side cache
Cache plug-ins for both OpenJPA and Hibernate are included ineXtreme Scale , which allows you to use eXtreme Scale as an automatic side-cache. Using eXtreme Scale as a cache provider increases performance when reading and querying data and reduces load to the database. There are advantages thateXtreme Scale has over built-in cache implementations because the cache is automatically replicated between all processes. When one client caches a value, all other clients will be able to utilize the cached value.
In-line cacheWhen used as an in-line cache, eXtreme Scale interacts with the back-end using a Loader plug-in. This scenario can simplify data access by allowing applications to access the eXtreme Scale APIs directly. Several different caching scenarios are supported in eXtreme Scale to make sure the data in the cache and the data in the back-end are synchronized. The following diagram illustrates how an in-line cache interacts with the application and back end.
Figure 2. In-line cache
Parent topic:Database integration: Write-behind, in-line, and side caching
Sparse and complete cache
Data pre-loading and warm-up
Database synchronization techniques
Invalidate stale cache data