27.3. Local Server-Side Response Cache

RESTEasy has a local, server-side, in-memory cache for your JAX-RS services. It automatically caches marshaled responses from HTTP GET JAX-RS invocations if your JAX-RS resource method sets a Cache-Control header. When a GET is received, the RESTEasy Server Cache checks whether the URI is stored in the cache. If true, the marshaled response is returned without invoking your JAX-RS method. Each cache entry has a maximum age for which the specifications in the Cache-Control header of the initial request are valid. The cache also automatically generates an ETag using an MD5 hash on the response body. This lets the client perform HTTP 1.1 cache revalidation with the IF-NONE-MATCH header. The cache will also perform revalidation if there is no initial cache hit, but the JAX-RS method returns a body with the same ETag.
To set up the server-side cache with Maven, you must use the resteasy-cache-core artifact: 
<dependency>
   <groupId>org.jboss.resteasy</groupId>
   <artifactId>resteasy-cache-core</artifactId>
   <version>1.1.GA</version>
</dependency>
Next, add a ServletContextListener: org.jboss.resteasy.plugins.cache.server.ServletServerCache. You must specify this after the ResteasyBootstrap listener in your web.xml file. 
<web-app>
    <listener>
        <listener-class>
            org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
        </listener-class>
    </listener>

    <context-param>
        <param-name>resteasy.server.cache.maxsize</param-name>
        <param-value>1000</param-value>
    </context-param>

    <context-param>
        <param-name>resteasy.server.cache.eviction.wakeup.interval</param-name>
        <param-value>5000</param-value>
    </context-param>

    <listener>
        <listener-class>
            org.jboss.resteasy.plugins.cache.server.ServletServerCache
        </listener-class>
    </listener>

    <servlet>
        <servlet-name>Resteasy</servlet-name>
        <servlet-class>
            org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher
        </servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>Resteasy</servlet-name>
        <url-pattern>/rest-services/*</url-pattern>
    </servlet-mapping>

</web-app>
The cache implementation is based on the JBoss Cache project. You can set two context-param configuration variables: resteasy.server.cache.maxsize sets the number of elements that can be cached, and resteasy.server.cache.eviction.wakeup.interval sets the rate at which the background eviction thread runs to purge the cache of stale entries.