Ehcache SimplePageCachingFilter

Add caching layer on your web application, with out modifying the code.

SimplePageCachingFilter

Ehcache has an out-of-box of solution for this ‘SimplePageCachingFilter’.
SimplePageCachingFilter is caching filter can be use full for html or any other response type
e.g JSON or xml. It uses singleton Ehcache manager to store contents. Cache keys are calculated
using the URI and query string. /exampleData?user=admin&role=admin.

There is another variant of ‘SimplePageCachingFilter’ based on headers ‘SimpleCachingHeadersPageCachingFilter’.
This filter take account headers for cache key. It take three account of headers

  • ETag
  • Last-Modified
  • Expires

Configuration

cacheName
Cache used by filter for storing content

blockingTimeoutMillis
the time, in milliseconds, to wait for the filter chain to return with a response on a cache miss. This is useful to fail fast in the event of an infrastructure failure.

varyHeader
set to true to set Vary:Accept-Encoding in the response when doing Gzip. This header is needed to support HTTP proxies however it is off by default.

Web.xml

<filter>
<filter-name>SimplePageCachingFilter</filter-name>
 <filter-class>net.sf.ehcache.constructs.web.filter.
SimplePageFragmentCachingFilter
 </filter-class>
 <init-param>
  <param-name>cacheName</param-name>
  <param-value>simplePageCache</param-value>
 </init-param>
</filter>
<filter-mapping>
<filter-name>SimplePageCachingFilter</filter-name>
 <url-pattern>/*</url-pattern>
</filter-mapping>

Ehcache configuration

<Ehcachexmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="../../main/config/ehcache.xsd">
<diskStorepath="java.io.tmpdir"/>
 <defaultCache
   maxEntriesLocalHeap="10"
   eternal="false"
   timeToIdleSeconds="5"
   timeToLiveSeconds="10"
   overflowToDisk="true"
   />
  <!-- Page and Page Fragment Caches -->
<cachename="simplePageCache"
  maxEntriesLocalHeap="10"
  eternal="false"
  timeToIdleSeconds="10000"
  timeToLiveSeconds="10000"
  overflowToDisk="true">
</cache>
</ehcache>

Pros

  • No code is required.
  • It allows the content compressing.
  • This can be integrated with Spring WebFramework too.

Cons

  • It do caching based on complete response.
  • It doesn’t take custom headers in account.

RESTFul Service example using Apache CXF and Spring

In recent times there is lot of growth in RESTFul services. I thought it would be nice to talk about it.

This example is using Apache CXF and Spring. There are some other frameworks e.g Jersey (Reference Sun implementation), RestEasy, the JBoss choice and Apache CXF.

Here is bacic web configuration adding Spring context and CXF tranport servlet.

  <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/services.xml</param-value>
    </context-param>


    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <servlet>
        <servlet-name>CXFServlet</servlet-name>
        <servlet-class>org.apache.cxf.transport.servlet.CXFServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>CXFServlet</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>

There is Cities service using Spring annotations, this has been configured using Spring annotation
Second annottatiions is of CXF to define the mount point REST service

@Service("timeService")
@Path("cities")
public class CitiesListingService {

    @GET
    @Produces({"application/json", "application/xml"})
    public RestFulCities getCities() {
        List<City> cities = new LinkedList<City>();
        cities.add(new City("New Delhi", "011", "19M"));
        cities.add(new City("Mumbai", "022", "21M"));
        cities.add(new City("Chennai", "044", "10M"));
        RestFulCities restFulCities = new RestFulCities();
        restFulCities.setRestFulCityList(getCities(cities));
        return restFulCities;
    }

Here is Spring configuration for connection cxf and spring beans together.

<context:component-scan base-package="com.techartifact.example.spring"/>

    <import resource="classpath:META-INF/cxf/cxf.xml"/>
    <import resource="classpath:META-INF/cxf/cxf-extension-jaxrs-binding.xml"/>
    <import resource="classpath:META-INF/cxf/cxf-servlet.xml"/>

    <jaxrs:server id="restContainer" address="/">
        <jaxrs:serviceBeans>
            <ref bean="timeService"/>
        </jaxrs:serviceBeans>
        <jaxrs:extensionMappings>
            <entry key="json" value="application/json"/>
            <entry key="xml" value="application/xml"/>
        </jaxrs:extensionMappings>
        <jaxrs:providers>
            <ref bean="jaxbXmlProvider"/>
        </jaxrs:providers>
    </jaxrs:server>

    <!-- Webservice message handlers -->
    <bean id="jaxbXmlProvider" class="org.apache.cxf.jaxrs.provider.JAXBElementProvider">
        <property name="jaxbElementClassNames" ref="elements"/>
    </bean>

    <util:list id="elements">
        <value>com.techartifact.example.spring.model.RestFulCity</value>
        <value>com.techartifact.example.spring.model.RestFulCities</value>
    </util:list>

Yes that’s it. Now build the code and run it.

Run example

Download full example code from here spring-RESTapplication

Go to project directory [spring-RESTapplication] in command shell and run following command using maven

mvn clean package
mvn -Pcargo-run

http://localhost:8080/springrest/rest/cities

CXF can also produces output in json format, use following url to see out put in json

http://localhost:8080/springrest/rest/cities.json