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.

/*****
<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

User specific Preferences in Liferay

As per JSR 168 Specificaiton Portlet Preferences are user specific and may be shared across portlets/pages ( NOT Mandatory: config/edit_shared modes)  which depends on portlet container.

If you have Websphere Portlet development experience you will wonder why preferences are not ‘user specific’  in liferay.

In this post I will explain how to solve this mystery and make your user specific preferences work in Liferay too.

Preferences in this example :
Portlet shows two  preference values  in VIEW mode JSP:  A. Sets dynamically by API B. From portlet.xml.
Edit Mode shows and allow to update preferences.
processAction stores updated  preferences.

Really simple use  isn’t it ?

Expected Behavior:
When user Bob logs in to portal and set his preferences, he can see them in VIEW mode. So preferences are personalized only for Bob. When Alice/another user logs in to Portal she can set her preferences which is only for her, no other user can see.

In Websphere portal: As per Expected.

In Liferay portal: When Bob logs in and set his preferences and it will be set for Alice and David too .i.e when Alice logs in to portal she can see preferences values set by Bob. If she too updates, it overwrites value set by Bob.

I was wondering  why its happening like this…because as  per JSR if user sets Preferences in EDIT/VIEW/HELP  mode it is user specific only.

Solution : Liferay supports  great level of customization for preferences (I will explain it  in details in my future posts).

But by default  Liferay sets  some customized levels for preferences  ‘ON’.

So in order to make  preferences  user specific in liferay, add following entries to liferay-portlet.xml :

<portlet>
....
<preferences-unique-per-layout>false</preferences-unique-per-layout>
<preferences-owned-by-group>false</preferences-owned-by-group>
....
</portlet>

Do these changes and redeploy portlet, now Bob’s preferences are for Bob only !!!

Useful Eclipse Shortcuts for Java Developer

Eclilpse is one of the most popular IDE for JAVA based development projects. As we know every technologies and tools comes with its own learning curve. Althaugh eclilpse is very easy to use but still lot  of the developers are not using it at its fullest capacity.

Here  in this post I will  show some very useful Eclipse shortcuts which will be useful for you in your day to day development.

1. Get rid of  manual Import statements  : Organize Imports ( Ctrl+Shift+O)
   After  you write a line of your code you may need to Impot classed used in your code.Otherwise eclipse will show  errors as you can see in this image. Organize Import will import classes if found from class path of your project.

2. Quickly Go to File : Open Resource ( Ctrl+Shift+R)
   Project we have several packages, in order to go to the particular file developer need to traverse to file through packages/folders in Navigator /Package view.For  example I am looking for BaseModelImpl.java file  instead of going through all packages/folders
   Do : Open Resource ( Ctrl + Shift + R  ) and type BaseImpl it will show all files starts with BaseImpl you can select the file you need and  press OK to open. It supports  RegEx so you can type like Ba*Im*.java also to filter your search.It can locate any file in your project not limited to .java files.

3. Quickly locate JAR which contains ‘the class’ :  Open Type ( Ctrl+Shift+T)
   Several times I need to  know which particular  JAR contains the class I am interested in. For Example  I have couple of projects in workspace and I copy paste few lines from other project.Its giving errors as Eclipse not able to resolve classes. As its working in other projects,  I need to know which JAR file this class contains and I need to copy that jar file to my project and/or set in classpath.

4. Jump to Last Edit Location : (Ctrl+Q)
   Working with multiple source files is reality of development . When you are working with multiple source files and need to know in which file you made last changes you can easily Jump to last Edit Location using ( Ctrl+ Q).
5. Locate where this method is reffered in projects : (Ctrl+Shift+G) (Quick Search)
   In order to know where this particular method/variable is reffered not only in this project but other projects of workspace also. Select method in Editor and do Ctrl+Shift+G. In search view Eclipse will search its references in all projects in current workspace.