ETag : Use Cached Contents

[smart_umesh_123]

I tried the response.getCacheControl().setUseCachedContent(true). but it does not work.

Here is my portlet class

-

package com.mycompany.frs.portlet;

public class CacheDemo extends GenericPortlet

{ 

public void doView(RenderRequest request, RenderResponse response) throws PortletException, IOException

{

System.out.println("**---- " + this.getClass().getName() + "'s doView is started");

if (request.getETag() != null)

{

if (request.getETag().startsWith("MY_ETAG"))

{

System.out.println("/////// MARKUP IS VALID");

response.getCacheControl().setExpirationTime(30);

response.getCacheControl().setUseCachedContent(true);

return;

}

}

else

{

response.getCacheControl().setETag("MY_ETAG" + (new Date()));

response.getCacheControl().setExpirationTime(30);

PortletRequestDispatcher dispatcher = getPortletContext().getRequestDispatcher("/WEB-INF/CacheDemo.jsp");

dispatcher.include(request, response);

}

} 

}

portlet.xml =

<portlet>

        <description>CacheDemo</description>

        <portlet-name>CacheDemo</portlet-name>

         <display-name>CacheDemo</display-name>

         <portlet-class>com.mycompany.frs.portlet.CacheDemo</portlet-class>      

         <supports>

             <mime-type>text/html</mime-type>

             <portlet-mode>VIEW</portlet-mode>

         </supports>

         <supports>

             <mime-type>text/html</mime-type>

             <portlet-mode>EDIT</portlet-mode>

         </supports>

         <supports>

             <mime-type>text/html</mime-type>

             <portlet-mode>HELP</portlet-mode>

         </supports>

         <portlet-info>

             <title>CacheDemo</title>

             <short-title>CacheDemo</short-title>

         </portlet-info>

         <expiration-cache>30</expiration-cache>          

     </portlet>

CacheDemo.jsp

<%@page import="java.util.Date"%>

<H1> Hello Friends, I am cached contents !! </H1>

<%= new Date() %>

Platform : Jboss GateIn 3.1

Problem :

When I refresh the page after 30 seconds, the portlet vanishes from the Portal page.

When I again refresh the page immediately, the portlet appears, with the cached contents. That is, it does not show the current date

-----------------

Thanks

Umesh Pathak

[ndkhoiits]

I confirmed that this's a bug from GateIn, UIPortletLifecycle hadn't cared the case PortletInvocationResponse is instance of RevalidateMarkupResponse.

Please create an issue at https://jira.jboss.org/browse/GTNPORTAL

Thank in advance

[ndkhoiits]

I've just created an issue for your problem, u can watch its if you want https://issues.jboss.org/browse/GTNPORTAL-1780

[smart_umesh_123]

Thanks Khoi !!

[hoang_to]

The exception thrown as you made the second render request is due to a bug of GateIn Portlet Container as mentionned by Khoi.

The second issue ( the portlet window still kept the outdate content) is caused by the ETag validation in your portlet

if (request.getETag().startsWith("MY_ETAG"))

{

}

...........

response.getCacheControl().setETag("MY_ETAG" + (new Date()));

[hoang_to]

If you clear the browser history, then refresh the page (should put the portlet window on the Home page and access as annonymous user), the content of portlet is updated

[ndkhoiits]

In your example, the if (request.getETag().startsWith("MY_ETAG")) clause alway returns true, so the cached value is rendered instead of get the fresh content.

The cached portlet is used when you want to have a portlet which display news, information.. for instance. And the ETag is set as a validation token to indicate that the content has been changed.

The following code is an example for this case:

public void doView(RenderRequest request, RenderResponse response) throws PortletException, IOException
{
   if (request.getETag() != null)
   {
      if (markupIsStillValid(request))
      {
         System.out.println("\n\nMARKUP IS VALID");
         response.getCacheControl().setExpirationTime(30);
         response.getCacheControl().setUseCachedContent(true);
         return;
      }
   }

   response.getCacheControl().setETag(String.valueOf(System.currentTimeMillis()));
   response.getCacheControl().setExpirationTime(30);
   getPortletContext().getRequestDispatcher("/WEB-INF/CacheDemo.jsp").include(request, response);
}

private boolean markupIsStillValid(RenderRequest request)
{
   boolean valid = false;
   if (Math.abs((Long.valueOf(request.getETag()) - System.currentTimeMillis())) < 100000)
   {
      valid = true;
   }
   return valid;
}