JPA 2-level caching - jpa

Question

Sorry for a providing a less specific title. Actually I am in a mess.
My actual problem: To improve performance of the application.
Good Thing: The data is inserted/updated through JPA through out the application.
Technology used so far: Spring 3.2 framework with JPA 2.0 and hibernate 3.2.
So far we don't have a direct dependency on Hibernate anywhere in our code.
Coming back to the problem:
I am planing to implement 2nd level Query caching for some queries which always fetch same data (dropdown values).
My 1st question :Does JPA provides 2nd level caching by itself(without using EHcache or any such dependency)?
What I found so far is using this property we can enable 2nd level caching
query.setHint("org.hibernate.cacheable", true);
My 2nd Question: Do I need to provide dependency for Ehcache or Hibernate-Ehcache is enough?
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-ehcache</artifactId>
<version>4.0.0</version>
</dependency>
or should I also need to provide
<dependency>
<groupId>net.sf.ehcache</groupId>
<artifactId>ehcache-core</artifactId>
<version>${ehcacheVersion}</version>
</dependency>
My third question: What are the properties I need to add in my persistence.xml.
I am sure about these two properties:
<property name="hibernate.cache.use_query_cache" value="true"/>
<property name="hibernate.cache.use_second_level_cache" value="true"/>
=====Thanks for the answer.This is the update might help the fellow developers.====
I am putting down the properties needs to be defined for enabling EHcache as lots of people face this exception
Caused by: org.hibernate.cache.NoCachingEnabledException: Second-level cache is not enabled for usage [hibernate.cache.use_second_level_cache | hibernate.cache.use_query_cache]
because of property mismatch and dependency mismatch.
The following property should work for hibernate 4.x along with Ehcache 2.4.3
<property name="hibernate.cache.use_second_level_cache" value="true"/>
<property name="hibernate.cache.use_query_cache" value="true"/>
<property name="hibernate.generate_statistics" value="true"/>
<property name="hibernate.cache.provider_configuration_file_resource_path" value="classpath:ehcache.xml" />
<property name="hibernate.cache.region.factory_class" value="org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory"/>

Answer 1

My 1st question :Does JPA provides 2nd level caching by itself (without
using EHcache or any such dependency)?
No, it doesn't. JPA is just a standard and doesn't provide any implementation. Hibernate provides implementation for JPA (EntityManager, EntityMangerFactory, etc) along with its own ORM implementation (Session, Session Factory, etc). Therefore, you need EHCache to support 2nd level cache. However, you can use JPA annotations/config for caching but that requires changes in persistence.xml.
Following two links explains each configuration options:
Caching using Hibernate specific classes/annotations.
Caching using JPA specific classes/annotations (with Hibernate as JPA provider)
My 2nd Question: Do I need to provide dependency for Ehcache or
Hibernate-Ehcache is enough?
You need to add ehcache-core, hibernate-ehcache and slf4j-simple (EHCache uses slf4j for logging). For dependencies details, check Hibernate EHCache Maven Dependencies section on this link.
My third question: What are the properties I need to add in my
persistence.xml.
If you go by JPA way, then the sample persistence.xml would be like:
<persistence-unit name="FooPu" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
...
<shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
<properties>
...
<property name="hibernate.cache.provider_class" value="org.hibernate.cache.SingletonEhCacheProvider"/>
<property name="hibernate.cache.use_second_level_cache" value="true"/>
<property name="hibernate.cache.use_query_cache" value="true"/>
</properties>
</persistence-unit>