The latest version of open source caching framework Ehcache supports write-behind caching and transaction management using Java Transaction API (JTA). It also includes a Hibernate 3.3 caching plugin, Bulk Loading API for clustered caches, and runtime cache reconfiguration.
Ehcache 2.0 introduces write-through and write-behind caching. Write-through caching pattern is used by the applications to write data to the cache which causes writes to an underlying resource (e.g. a database). The cache acts as a facade to the underlying resource. Write-behind caching pattern uses the same client API, but the write happens asynchronously. The write-behind caching feature, supported as part of the new Ehcache API, works with asynchronous batching of updates to the database.
Transaction Management: The new JTA support enables the cache to participate as an XA resource in JTA transactions. It automatically detects and uses the following transaction managers in the order: Generic JNDI (e.g. Glassfish, JBoss, Weblogic, JTOM), WebSphere, Bitronix JTA Transaction Manager, and Atomikos. Ehcache 2.0 is not a "transactional" cache for Hibernate purposes. Ehcache 2.1 (beta version was recently released) provides the JTA support for Hibernate.
Ehcache 2.0 also includes an express mode that be used to cluster the application data via configuration changes, whether the data is in Hibernate, a distributed cache, or session objects. It supports distributed caching as a Hibernate second-level cache, as well as directly through the Ehcache API. Switching between local and distributed implementations is done with a configuration change. Other features in the new version include:
- Bulk Loading: The bulk loading mode is used for loading data into caches using the Terracotta Server Array. This option can be used for the use cases like cache warming where caches need to be filled before bringing an application online and for periodic batch loading.
- Configuration Management: There is a new management feature that provides dynamic configuration for Ehcache, whereby cache parameters like Time-To-Idle (TTI) and Time-To-Live (TTL) can be changed using the Terracotta management console or any JMX-compliant tool.
- Web Sessions: An upgrade to Terracotta Web Sessions product, called Terracotta Express Web Sessions, is also part of the latest version and provides the HTTP session clustering in the web applications.
- TC Server Array: The Terracotta Server Array (TSA) has been re-engineered to provide the caching features with cluster coherence, high availability and persistence.
- OSGI: Support for OSGi containers is also included.
Ehcache 2.0 includes support for Java EE containers like WebLogic, Tomcat, JBoss, and Jetty. In a related news item, Ehcache team also released the Ehcache Server which provides RESTful and SOAP APIs to Ehcache framework.