Caching In Hibernate

àCache/Buffer is a tempery memory that holds results or data and uses that data or results across the multiple same request given by application

àThe Process of storing results in cache/buffer and using that result across the multiple requests or execution of the application is called caching/buffering

àIn Client-Server application if caching is enabled at client-side it reduces network roundtrips between client and server application

àEvery Browser window contains buffer and stores request related response. Response Result the buffer of browser window reduces network roundtrips between browser window and webserver across the multiple same requests given by browser window

àHibernate supports two levels of caching

1.First level caching / L1 caching ( At Hibernate Session Object)

2.Second Level caching/L2 Caching(At Hibernate Session Factory Object)

First level cache is built-in cache. Second Level cache is Configurable Cache.

i.e second level cache will be enable when programmer configures it manually.

(a1-->g1) is first request operations

(a2-->c2) second request operations

(a3-->c3) third request operations

State 1:

A1-->Session Object uses initial request

B1-->Searched for that query result in level1 cache of session object 1(Not available)

C1-->searches for query result in level2 cache(not available)

D1-->Hibernate application interacts with database software and gets query execution related results

E1-->Hibernate software registers the results in level2 cache

F1-->Hibernate software also registers the result in level1 cache of session object1

G1-->Session object1 uses the result to application

State 2:

A2-->Session Object2 gives same request once again

B2-->searches for result in level 1 cache of session object1(available)

C2-->Session object1 collects the result from its own level 1 cache and passes to client application

State 3:

A3-->Session object2 of same client application gives same request to database software

B3-->Searches for the result in level1 cache of session object2(not available)

C3-->Searches for the result in level2 cache(available)

D3-->Collects the result from level2 cache and registers with level 1 cache of session object2

E3-->Session Object 2 gives the result to client application

Results in level1,level2 cache will be stored in the form of hibernate POJO class object

The result of level1 cache and level2 cache will be updated automatically at regular intervals

Cache Implementations

Caches are complicated pieces of software, and the market offers quite a number of choices both open source and commercial. Hibernate follows these open-source softwares

•EHCache(org.hibernate..cache.EhCacheProvider)

•OSCache(org.hibernate.cache.OSCacheProvider)

•SwarmCache(org.hibernate.cache.SwarmCacheProvider)

•Jboss TreeCache(org.hibernate.cache.TreeCacheProvider)

Cache Configurations:

 <hibernate-configuration>

<session-factory>

……

<property name=“hibernate.cache.provider_class”> org.hibernate..cache.EhCacheProvider</property>

….

</hibernate-configuration>