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Using Jcache SPI for using Hazelcast as L2C for Hibernate

This is an alternative approach of using Hazelcast-hibernate plugin to use Hazelcast as caching provider for Hibernate. The plugin can be found here. Also, distributed query cache which is not supported by the plugin can be used this way.

About Jcache

JCache (JSR 107) is a standard caching API for Java. It provides an API for applications to be able to create and work with in-memory cache of objects. Hibernate has started to support Jcache implementations for L2C with version 5.2. Using only a CachingProvider implementation, L2C can be used for SessionFactory objects in Hibernate.

Dependencies

• Include hibernate-jcache dependency in your program. The version must be the same as hibernate-core version.

In pom.xml:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-jcache</artifactId>
    <version>${version.hibernate-core}</version>
</dependency>

• Use hazelcast-client or hazelcast dependency to use client or server mode respectively.

<dependency>
    <groupId>com.hazelcast</groupId>
    <artifactId>hazelcast</artifactId>
    <!-- artifactId>hazelcast-client</artifactId -->
    <version>${version.hazelcast}</version>
</dependency>

Hibernate JCache Region Factory

In hibernate.cfg.xml:

For Hibernate 5.2.x:

<property name="hibernate.cache.region.factory_class">org.hibernate.cache.jcache.JCacheRegionFactory</property>

For Hibernate 5.3.0 and higher:

    <property name="hibernate.cache.region.factory_class">jcache</property>

Hazelcast Provider Type

CLIENT: You can connect to an existing Hazelcast cluster and store the cache data there. Then you can scale the cluster up or down independent from your app. Data resides in L2C can be available even a SessionFactory is closed or application is shut down. So this makes L2C available across SessionFactories and Hibernate applications.

To try client version on the code sample, run StartCluster first to create a cluster.

EMBEDDED: A new Hazelcast instance is created along with your application. This instance cannot be scaled up or down unless you run or shutdown another Hibernate application with the same server config. Latency of communicating to Hazelcast Cluster will be less than the client mode.

You can see the difference between client and embedded version here

In hibernate.cfg.xml:

• Using Native Client

<property name="hibernate.javax.cache.provider">com.hazelcast.client.cache.impl.HazelcastClientCachingProvider</property>
<property name="hibernate.javax.cache.uri">hazelcast-client.xml</property>

• Using Embedded Hazelcast Instance

<property name="hibernate.javax.cache.provider">com.hazelcast.cache.impl.HazelcastServerCachingProvider</property>
<property name="hibernate.javax.cache.uri">hazelcast.xml</property>

Cache Configuration

To see your cache statistics on Hazelcast Management Center, you have to enable statistics (disabled by default) for the cache configuration of Hazelcast instance. In hazelcast.xml, see ` part:

<cache name="custom.cache.region.name">
    <statistics-enabled>true</statistics-enabled>
    <management-enabled>true</management-enabled>
</cache> 

If you do not define a specific region name, the default cache configuration is going to be used for this region, hence will not be visible on Management Center. To apply a config to all regions, you can use wildcards for name property (e.g. name="*").

For other cache configurtion properties, see <cache> config on full hazelcast.xml example here. Eviction size and policy properties might be useful for this case.