In servlet :
request.setAttribute(message,”Hello World!”);

In JSP :
${message}

On HTML it is being rendered as : ${HTML}

If you are also facing the same problem use following page directive at top of the page :

That will solve the problem.

Suppose you want to open “view.jsp” from “details” folder, if you use “*details*view.jsp” wont help. It will apply the regex on filename only. You should use file separators in the regex for this. You need to separate the regex for matching path and regex for matching filename with “/”. For example for the above search you can type : “*language*/view*jsp“

I have following code in my project

I have configured hibernateSession in my components.xml as following


<persistence:hibernate-session-factory name="hibernateSessionFactory" />
<persistence:managed-hibernate-session name="hibernateSession" session-factory="#{hibernateSessionFactory}"
auto-create="true" />

And in one of the seam component I have a method to create a new user which looks like as follows

public void createNewUserInDatabase(){
User user = new User("Ganesh","Gembali");
hibernateSession.persist(user);
}


Following code getting executed with out any stacktrace. But I could not find this new entry in my database. After checking with the seam manual and community forums, its because of missing Transactional annotation for the method. So you must use transactional annotation when you want to persist using seam managed hibernate session.


@Transactional
public void createNewUserInDatabase(){
User user = new User("Ganesh","Gembali");
hibernateSession.persist(user);
}


Any suggestions are always welcome. Stay tuned for more Seam findings and tips .

If you are facing PermGenSpace problem you should use “-XX:MaxPermSize=1024m” java option. Please note that value depends on needs of your application.

If you are facing OutOfMemory problem you should use “-Xmx1024M” . Again the value depends on your application needs.

How to set these on windows ?
You can create them as system properties with name MAVEN_OPTS and value “-Xmx1024M -XX:MaxPermSize=1024m“.

On Unix based systems like ubuntu :
You can add following two lines to your .profile file in home folder. Change the values according to your need.

MAVEN_OPTS='-Xmx1024M -XX:MaxPermSize=1024m'
export MAVEN_OPTS

You should use single quotes only here. If you use double or no quotes, it will complain. Hope this is useful for you. If there is a better way, please let the world know about .

” Should show a horizontal one level menu. The number of menu items in the menu could vary and it should support IE (5.5, 6, 7) , Firefox (2,3) , Opera , Safari,Chrome .”

Great , its too easy. There are many examples in the net to create some thing like this. But the hard part started with the following constraint.

1. The menu should take whole width of the page
2. Width individual elements should be based on the title of the item. The title are generated dynamically by the backend.
3. It should look alike in all browsers.

“

The solutions ( that I have written and got from net ) worked fine with latest versions of all browsers. But IE ( as usual ) behaved differently in different versions. One solution to this problem can be writing seperate CSS for each browser and including them conditionally. But couldn’t satisfy the coonstraint no 3.

So I finally went for javascript using the basic functions which works across all browsers. The logic is simple.
Step 1 : Use CSS to make the horizontal list.
You can use this CSS
li{
display:inline;
float: left;
width:auto;
height:40px; // You should specify this to restrict wrapping of the title
}

Step 2 : Adjusting the widths
Here I have used javascript to do the job of adjusting widths to satisfy above constraints.
First calculate widths of individual titles and sum them up.
Calculate the difference between width of total page total width all titles.
This difference must be distributed to all individual items so that whole menu will occupy the whole page and the width based on width of title.
You can see the HTML code here :

    <ul id="navigation">
      <li><a href="#"><span class="space">Accueil</span></a></li>
      <li><a href="#"><span class="space">Accueil</span></a></li>
      <li><a href="#"><span class="space">Accueil</span></a></li>
      <li><a href="#"><span class="space">Mon programme</span></a></li>
      <li><a href="#"><span class="space">Mon programme</span></a></li>
      <li><a href="#"><span class="space">Mon programme</span></a></li>
      <li><a href="#"><span class="space">Qui sommes nous ?</span></a></li>
    </ul>

And javascript code looks like this

var ulItem = document.getElementById("navigation");
var spanItems = ulItem.getElementsByTagName("span");
var total = 0;
for(var i=0;i < spanItems.length ; i++){
	total = total + spanItems[i].offsetWidth;
}
var difference =  940 - total;
var extraWidthForEach = (difference / spanItems.length)-11;
for(var i=0;i < spanItems.length ; i++){
	spanItems[i].style.width = spanItems[i].offsetWidth + extraWidthForEach+"px";
}

This way makes your site SEO compatible as you haven’t generated the html code with javascript and works perfectly with all browsers. Hope it will be useful for at least one of you. In case you found some better solution or some problem with my code please let me know. I have attached a sample html here ( I couldn’t attach html so pasted the code on to a pdf file ).

<plugin>
	<groupId>org.mortbay.jetty</groupId>
	<artifactId>maven-jetty-plugin</artifactId>
	<version>6.0.0</version>
	<configuration>
		<webDefaultXml>src/test/resources/webdefault.xml</webDefaultXml>
		<systemProperties>
			<systemProperty>
				<name>jetty.port</name>
				<value>8081</value>
			</systemProperty>
		</systemProperties>
		<contextPath>/</contextPath>
		<scanIntervalSeconds>3000</scanIntervalSeconds>
		<scanTargets>
			<scanTarget>src/main/webapp/WEB-INF</scanTarget>
			<scanTarget>../target/classes</scanTarget>
		</scanTargets>
	</configuration>
</plugin>

It was working fine in one project , but in another project I got following error stack trace when executing mvn jetty:run
[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'jetty'.
[INFO] artifact org.apache.maven.plugins:maven-jetty-plugin: checking for updates from central
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] The plugin 'org.apache.maven.plugins:maven-jetty-plugin' does not exist or no valid version could be found
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2 seconds
[INFO] Finished at: Mon Dec 29 10:53:14 IST 2008
[INFO] Final Memory: 2M/4M
[INFO] ------------------------------------------------------------------------

Although we have specified the groupId in our pom, maven still trying to find maven-jetty-plugin in org.apache.maven.plugins group. I don’t know why it is resolving it like that .

I found following suggestions in the net

• Specify proper group id : which we did already
• Remove ~/.m2/repository/org/apache/maven/plugins folder as the local maven repository might have got corrupted
• Remove all folders and files with with jetty in their names

But none of the above worked for me. Finally I tried adding the org.mortbay.jetty plugin group to my settings.xml as follows

 <pluginGroups>
    <pluginGroup>org.mortbay.jetty</pluginGroup>
  </pluginGroups>

Then it worked like a charm. I would like to hear any suggestions or reasons why its behaving like this. Thanks in advance for your suggestions and directions.

• Liferay
• JBoss
• Exo Portal

For now I will use Liferay to deploy my portlet. But the portlet that we are going to develop can deployed any portal system with minor changes.

Setting up environment :
We would require following softwares installed .

• Java 1.4 or later
• Eclipse 3.2+
• Sysdeo Plugin for Debugging
• Lifeary + Tomcat bundle
• Maven 2.0.9

Creating basic project structure:

You can use maven archetype to create the basic project structure needed for developing a portlet. Execute following maven command to create structure

mvn archetype:generate
Once you execute the above command , you should see following list

......................................................................................................................
......................................................................................................................
12: internal -> maven-archetype-mojo (A Maven Java plugin development project)
13: internal -> maven-archetype-portlet (A simple portlet application)
14: internal -> maven-archetype-profiles ()
15: internal -> maven-archetype-quickstart ()
......................................................................................................................
......................................................................................................................
Choose a number: (1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22/23/24/25/26/27/28/29/30/31/32/33/34/35/36) 15: :


Choose portlet archetype and give the proper parameters it needed. You can learn more about maven archetypes here.

Converting to Eclipse Project :

With maven we can create eclipse descriptors easily so that we can use eclipse to work on our project. Use following maven command

mvn eclipse:eclipse

After you have imported this project into eclipse , You should see the following file structure in eclipse ( Assuming you named your project as “samplePortlet”).

Now our portlet is ready and you can use mvn clean:package to package it to a war file.

Tweaking it to make it work on any portal

The portlet we have developed above can be deployed only on Pluto container(Pluto is the Reference Implementation of the Java Portlet Specfication) . Because the maven archetype we used already configured its web.xml to use Pluto container. You can check the web.xml in yout project folder. Remove all other information related to portal from web.xml. Just retain generic tags and any tag library (other than portlet tag libraries) configurations.If you dont need any configurations, in simplest case it should look like as follows

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE web-app PUBLIC
                        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
                        "http://java.sun.com/dtd/web-app_2_3.dtd">
<web-app>
    <display-name>Sample Portlet</display-name>
    <description>
                   Automated generated Application Wrapper
    </description>
</web-app>

Another bug is with portlet.xml. It gives a wrong portlet class name in it. It just gives the package name. Append class name to this value in portlet.xml . If you haven’t changed the default class name (which is “MyPortlet.java”) , the portlet-class tag should look as follows

<portlet-class>
    com.xebia.samplePortlet.MyPortlet
</portlet-class>

The portlet specific tags in web.xml will be added by portal container once we deploy it.

Deploying to portal container

We can deploy the above portlet on any portal container by just adding some descriptor files which are specific to each portal container. If it is liferay , we need to add a xml file with name liferay-display.xml under WEB-INF. Its content looks like follows

<pre lang="xml">
<?xml version="1.0"?>
<!DOCTYPE display PUBLIC "-//Liferay//DTD Display 5.1.0//EN"
"http://www.liferay.com/dtd/liferay-display_5_1_0.dtd">
<display>
	<category name="Sample Portlets"> // Under what category should this portlet should be shown
		<portlet id="samplePortlet" /> // Portlet name specified in portlet.xml
	</category>
</display>

Debugging the code

A Portlet is a web application running in a J2EE container. Common web debugging tools like Sysdeo can be used along with eclipse. Sysdeo is a eclipse plugin helps in debugging portlet applications. Once we are done with configuring sysdeo , we can configure project to be a application running in tomcat using project properties.

This environment helps the developer to quickly start with portlet development . Because we are using maven here , we can make use of all the benfits maven provides like Reports generation , dependency managemt , etc.

“In recent times Agile methodology have proved its worth by successfully executing the projects. It minimizes the risk by developing software in short amounts of time. With this iterative model it also minimizes the cost of change in requirements, which makes it suitable for current dyanmic market. Two main practices that helps the developer to incorporate the change are refactoring and simple design. But when it comes to doing these two things with a completely new technology, it might be hard to implement.

In this article I am going to share some of my experiences with my first project. This is an agile project based on a technology which is new to the whole team. I spent around two weeks in understanding the technical features and strengths of the technology.Where as others in the team had never worked with it or similar technology. Here I will discuss about some mistakes that ( I feel )we did while executing the project. “

… Readmore

“In web development, Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in a markup language. It has a simple syntax, and uses a number of English keywords to specify the names of various style properties. Its specifications were maintained by W3C. It still hasn’t became a standard over all browsers.

Here I want to share some of my experiences( pains I went through ) while developing styles for my previous projects. One of the project is based on div structure and other is based on table and div structure….. Readmore“