Liferay Session Sharing : Made Easy

Inter portlet coummunication is made easy with JSR 286. But all IPC (Inter-Portlet Communications)  mechanisms (public render parameters,Events ) is about ACTION-to-VIEW.

• What I mean by ACTION-to-VIEW is on “action phase” of one portlet information is shared and made available to specific/all portlet’s “view phase”.
• There are use cases  where we need a IPC mechanism to share information between portlets of different WARs  in VIEW-to-VIEW .It means One portlet will share information from its VIEW phase and will be available to other Portlet in VIEW phase.

By default Each WAR has its own session and will not be shared with other WARs.

Liferay provides a mechanism by which Portlets can share session attributes across WARs.

How to Setup :

1.liferay-portlet.xml

For Portlets who will share (i.e setAttribute() ) session attributes(s) need to add following entry in liferay-portlet.xml

<portlet>...
<private-session-attributes>false</private-session-attributes>
</portlet>

2. Use Namespace prefix to Share/Get shared session attribute:

By default “LIFERAY_SHARED_”  prefix is used for sharing session attribute to other WARs.  It can be customized with in portal.properties ‘s session.shared.attributes value.

portletSession.setAttribute( "LIFERAY_SHARED_mySpecialVar",value,PortletSession.APPLICATION_SCOPE);

Other portlet(s)  in different WAR  can access it :

portletSession.getAttribute( "LIFERAY_SHARED_mySpecialVar",PortletSession.APPLICATION_SCOPE);

3. Caveat :

Using Liferay’s custom Session Sharing mechanism Portlet can share session with other Portlet in Different WAR but not with the Servlet in Different WAR.

It can be shared with Servlet ( of Different WAR) via Portlet of that WAR.

How to Share with Servlet of Other WAR :-

Portlet One :

portletSession.setAttribute( "LIFERAY_SHARED_mySpecialVar",value,
PortletSession.APPLICATION_SCOPE);

Portlet Two:

Object value=  portletSession.getAttribute
( "LIFERAY_SHARED_mySpecialVar",PortletSession.APPLICATION_SCOPE);//getting shared value
portletSession.setAttribute
( "mySpecialVar",value,PortletSession.APPLICATION_SCOPE);//setting to 'local' session

Servlet Two:

request.getSession().getAttribute("mySpecialVar");

Developer has to be aware while sharing/accessing “shared” session attributes, also note that if prefix is customized need to change the source code.

I have developed a Utility which can make Liferay Session sharing easier for developers.

Its taking care of customized prefix also and provides neat way to set/access shared session attributes.

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<pre>* RUTVIJ SHAH MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. RUTVIJ SHAH SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
* THIS SOFTWARE IS IN AS-IS FORM, YOU ARE FREE TO RE-DISTRIBUTE/CHANGE WITHOUT ANY NOTIFICATION TO AUTHOR.
******/

package myapp.liferayImpl.session.util;

import com.liferay.portal.kernel.util.PropsUtil;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.portlet.PortletRequest;
import javax.portlet.PortletSession;

/**
* @author Rutvij Shah ( rutvij.shah@yahoo.com )
* LiferaySessionUtil provides helper methods to share your Session attributes
* across WARs.
*
*/
public class LiferaySessionUtil {
/***
* This prefix is used by Liferay Portal to detect Session Attributes
* for sharing betweeen WARs.
*/

private static final String LIFERAY_SHARED_SESSION_PREFIX=getSharedSessionPrefix();
private static final String LIFERAY_SHARED_SESSION_PREFIX_DEFAULT="LIFERAY_SHARED_";
/****
* It stores attribute as 'Shared' Attribute and will be available to other
* portlets in different WARs.
*
* Attributes shared by this method will be available to only Portlets,
* not other Web components i.e Servlet.
*
* @param key session Key to store value
* @param value
* @param request PortletRequest
*/
public static final void setGlobalSessionAttribute(String key,Object value,PortletRequest request){
if(key!=null){
String globalKey=getGlobalKey(key);
PortletSession portletSession=request.getPortletSession();
portletSession.setAttribute(globalKey,value,PortletSession.APPLICATION_SCOPE);
}
}
/****
*
* It provides access to get shared session attributes from other portles
* from diffrent WARs.
*
* @param key
* @param request
* @return
*/
public static final Object getGlobalSessionAttribute(String key,PortletRequest request){
Object value=null;
if(key!=null){
String globalKey=getGlobalKey(key);
PortletSession portletSession=request.getPortletSession();
value=portletSession.getAttribute(globalKey,PortletSession.APPLICATION_SCOPE);
}
return value;
}

/******
*
* It provides a way to further share 'Shared'Session Attributes from
* Portlet to other Web Components i.e Servlets .
*
* @param key
* @param request
*/
public static final void shareGlobalSessionAttribute(String key,PortletRequest request){
if(key!=null){
Object value=getGlobalSessionAttribute(key, request);
PortletSession portletSession=request.getPortletSession();
portletSession.setAttribute(key,value,PortletSession.APPLICATION_SCOPE);
}
}

/***
* Helper method to generate Global key using Liferay shared prefix
* @param key
* @return
*/
private static final String getGlobalKey(String key){
return LIFERAY_SHARED_SESSION_PREFIX+key;
}

/********
* Helper method to get Liferay's Session Sharing prefix
* Useful when Liferay is customized to use different prefix other than Default
*
* @return
*/
private static final String getSharedSessionPrefix(){
String value=null;
try {
/**
* Getting value from portal.properties
*/
value = PropsUtil.get("session.shared.attributes");
} catch (Exception ex) {
Logger.getLogger(LiferaySessionUtil.class.getName()).log(Level.SEVERE, null, ex);
}

if(value !=null){
if(value.contains(LIFERAY_SHARED_SESSION_PREFIX_DEFAULT)){
//if default prefix is configured use it
value=LIFERAY_SHARED_SESSION_PREFIX_DEFAULT;
}else{
//use first one from the list of prefix configured
value=value.split(",")[0];
}
}else{
/**
* If none of the value configured use default one
* Note: Session Sharing may not work as none of the value configured.
*/
value=LIFERAY_SHARED_SESSION_PREFIX_DEFAULT;
}
return value;
}

}

Using this Util class  for same use case :

Portlet One :

LiferaySessionUtil.setGlobalSessionAttribute
("mySpecialVar",value, portletRequest); //adding 'proper' prefix will be taken care by Utility

PortletTwo:

Object value=  LiferaySessionUtil.getGlobalSessionAttribute
("mySpecialVar", portletRequest); //to get value for portlet
LiferaySessionUtil.shareGlobalSessionAttribute
("mySpecialVar", portletRequest);//to share value to servlets

As you can see if Portlet Two only need to share it with servlet no need of first line.

Servlet Two:

 request.getSession().getAttribute("mySpecialVar");

Feel free to share your comments on this. You can download LiferaySessionUtil.java  from here :  LiferaySessionUtil