Hibernate Caching

I found some useful information on internet about hibernate caching.I thought of sharing with everyone.
High-volume database traffic is a frequent cause of performance problems in Web applications. Hibernate is a high-performance, object/relational persistence and query service. In many cases, second-level caching can be just what Hibernate needs to realize its full performance-handling potential.

What is caching – Anything you can do to minimize traffic between a database and an application server is probably a good thing. In theory, an application ought to be able to maintain a cache containing data already loaded from the database, and only hit the database when information has to be updated. When the database is hit, the changes may invalidate the cache.

There are two different cache used in hibernate-
1. First Level cache – This is associated with session. This is default implemented in hibernate on a per-transaction basis. Hibernate uses this cache mainly to reduce the number of SQL queries it needs to generate within a given transaction. For example, if an object is modified several times within the same transaction, Hibernate will generate only one SQL UPDATE statement at the end of the transaction, containing all the modifications
2. Second level cache – This is associated with Session Factory object. It will survive Sessions and can be reused in new Session by same SessionFactory (which usually is one per application). By default the 2nd level cache is not enabled. This ‘second-level’ cache exists as long as the session factory is alive. The second-level cache holds on to the ‘data’ for all properties and associations for individual entities that are marked to be cached. The second level cache is responsible for caching objects across sessions.

Cache Type
EHCache (Easy Hibernate Cache) — http://ehcache.sourceforge.net/
OSCache (Open Symphony) — http://www.opensymphony.com/oscache/
SwarmCache — http://swarmcache.sourceforge.net/
JBoss TreeCache — http://jboss.org/wiki/Wiki.jsp?page=JBossCache

• EHCache -s an open source widely used java distributed cache for general purpose caching, Java EE and light-weight containers. It features memory and disk stores, replicate by copy and invalidate, listeners, cache loaders, cache extensions, cache exception handlers, a gzip caching servlet filter, RESTful and SOAP APIs and much more. Ehcache is available under an Apache open source license and is actively developed, maintained and supported.It support read only, Non strict Read/write,Read/write caching.It does not support transactional caching architecture.
• OSCache – is “a Java framework” developed by OpenSymphony that makes it easy to cache content in Web applications.It is a caching solution that includes a JSP tag library and set of classes to perform fine grained dynamic caching of JSP content, servlet responses or arbitrary objects.It provides both in memory and persistent on disk caches.They can allow your site to have graceful error tolerance .It support read only, Non strict Read/write,Read/write caching.It does not support transactional schema caching architecture.
• SwarmCache is a simple cluster-based caching solution based on JavaGroups. It supports read-only or nonstrict read/write caching. This type of cache is appropriate for applications that typically have many more read operations than write operations.It support read only, Non strict Read/write caching.It does not support ,Read/write and transactional caching architecture.It is is a cluster-based caching.
• JBoss TreeCache – is a powerful replicated (synchronous or asynchronous) and transactional cache. Use this solution if you really need a true transaction-capable caching architecture.

ref- http://www.devx.com/dbzone/Article/29685/1954
– http://javaexp.blogspot.com/2007/10/level2-caching-in-hibernate.html