Determining which cache to use

The following figure shows the caching options available from HTTP Server, WebSphere Application Server, and WebSphere Portal.  

The shortest path shows that pre-rendering is the fastest option.  However, the choice of which cache to use is not as easy as picking the fastest option.

Use the following set of considerations to decide which cache to use:

If you decide to use Web Content Management cache, use the following additional set of considerations to determine the type of Web Content Management cache to use:

Servlet caching (Dynamic Cache Service)

Servlet caching involves caching the request at the WebSphere Application Server layer. This type of caching is not as fast as pre-rendering, but it is faster than Web Content Management caching and, depending on your needs, can be more flexible.

Although servlet caching cannot cache personalized content, it can be used to selectively cache or not cache individual pages. Depending on the type of rendering that is used, servlet caching can be enabled to either cache the results of portlets or the Web Content Management servlet.

Servlet caching limitations

• Servlet caching must be re-enabled after a fix pack or cumulative-iFix is applied.  Keep a backup of your cachespec.xml file, so you can easily re-enable servlet caching.

• Restart the server after making changes to the cachespec.xml file.

• When specifying "pathinfo" components in a cache-id, include the Web Content Management library name in any "non-value" and "value" attributes. Additionally remove any "+" characters from the URLs.

• Error responses from the portlets and servlet are cached (such as file not found and exceptions), which is typically not expected and can cause problems in documents are removed from the live website temporarily.

• Specifying a URL to a site or site area in either the "non-value" or "value" attributes does not also specify the site or site area's children. The only way to do selective caching is to either:

  • Use the "non-value" attribute to specify the URL of every page that should not be cached.

  • Use the "value" attribute to specify the URL of every page that should be cached.

• For rendering portlets, the default context of the portlet cannot be cached.

• For rendering portlets, if alternate page design is enabled after caching, then the design will not display until after the cache is cleared.

Additional Servlet Caching Limitations with Servlet Rendering

• When using dynamic cache service with servlet rendering, be careful not to overwrite the existing cachespec.xml file.  Add your cache-id sections after the existing one.

• Unlike for rendering portlets, when using servlet rendering caching, if the following arguments are not specified in the cache-id, then the following behavior is observed:
  
  

  Argument	What happens if it is not specified
  id	Dynamic cache service does not distinguish between Draft and Published copies of the same object.
  pagedesign	Dynamic cache service does not distinguish between the default and alternate pagedesigns of the same content.
  version	Dynamic cache service does not distinguish between the current and previous versions of the same object.
  source	Library and content components do not render under some conditions.
  cmpntname	Library and content components do not render under some conditions.
  cmpntid	Library and content components do not render under some conditions.

• It’s recommended the specific ‘component’ entry below be added to disable Servlet-Caching for Web Content Management’s Utility Modules and Syndication, as caching these elements will break both the Utility Modules and Syndication:

<cache-id>  

   

   - Normal ‘component’ sections describing what to cache

   

   <component id="MOD" type="parameter">
       <required>false</required>
       <not-value>Subs</not-value>
       <not-value>Synd</not-value>
       <not-value>ItemDispatcher</not-value>
       <not-value>Syndication</not-value>
       <not-value>MemberFixer</not-value>
       <not-value>VersioningEnablement</not-value>
       <not-value>WorkflowEnablement</not-value>
      <not-value>PlutoUploadFile</not-value>
       <not-value>PlutoDownloadFile</not-value>
       <not-value>AJPECatSelect</not-value>

       <not-value>RefreshAllItems</not-value>
       <not-value>Template</not-value>
   </component>

</cache-id>

How to configure local rendering caching

1. Ensure that the dynamic caching service is enabled for the WebSphere Application Server.  

2. Define what is and is not cached in your cachespec.xml file.

3. Use the following commands to backup, then update the Local-Rendering portlet:

   • From a command-prompt, navigate to [WPS_ROOT]\installableApps

   • Copy ilwwcm-localrendering-portlet.war to ilwwcm-localrendering-portlet.war.backup

   • Make a new directory called wcm_lrp_war and navigate to it.

   • Run the following command:

• [WAS_ROOT]/java/bin/jar –xf ../ilwwcm-localrendering-portlet.war

  • Copy your cachespec.xml file to [WPS_ROOT]/installableApps/wcm_lrp_war/WEB-INF

  • Run the following command:

• [WAS_ROOT]/java/bin/jar –cf ../ilwwcm-localrendering-portlet.war *

4. Use the WebSphere Portal Administration page to re-deploy any modified portlets from the [WPS_ROOT]\installableApps directory.

5. [Optional] Install the dynamic cache monitor on the WebSphere Application Server.

How to configure remote rendering caching

1. Ensure that the dynamic caching service is enabled on the WebSphere Application Server.    

2. Define what is and is not cached in your cachespec.xml file for the WebSphere Application Server.

3. Use the following commands to backup, then update the Remote Rendering portlet:

   • From a command-prompt, navigate to [WPS_ROOT]\installableApps

   • Copy ilwwcm-remoterendering-portlet.war to ilwwcm-remoterendering-portlet.war.backup.

   • Make a new directory called wcm_rrp_war and navigate to it.

   • Run the following command:

• [WAS_ROOT]/java/bin/jar –xf ../ilwwcm-remoterendering-portlet.war

  • Copy your cachespec.xml file to [WPS_ROOT]/installableApps/wcm_rrp_war/WEB-INF

  • Run the following command:

• [WAS_ROOT]/java/bin/jar –cf ../ilwwcm-remoterendering-portlet.war *

4. Use the WebSphere Portal Administration page to re-deploy the modified portlets from the [WPS_ROOT]\installableApps directory

5. [Optional] Install the dynamic cache monitor for the WebSphere Application Server.

How to configure servlet rendering caching

1. Ensure that the dynamic caching service is enabled for the WebSphere Application Server.

2. Define what is and is not cached in your cachespec.xml file.

3. Use the following commands to backup, then update the WCM ear file:

• From a command-prompt, navigate to [WPS_ROOT]\wcm\installableApps

• Rename wcm.ear to wcm.ear.backup .

• Run the following command:
  [WAS_ROOT]/bin/earexpander.bat –ear wcm.ear –operationDir ./wcm_ear –operation expand

• Merge your cachespec.xml file with the one already existing in ./wcm_ear/ilwwcm.war/WEB-INF .  Do not overwrite the existing cachespec file.

• Run the following command:
  [WAS_ROOT]/bin/earexpander.bat –ear wcm.ear –operationDir ./wcm_ear –operation collapse

• Run the following Portal Config command(s) to redeploy the updated wcm.ear file: [WPS_ROOT]/config/WPSconfig.bat update-wcm-ear

4. [Optional] Install the dynamic cache monitor on the WebSphere Application Server.

Rendering Portlet Examples

Servlet Rendering Examples