#learning j2ee

[gauravdaga]

Writing annotation based JSR 286 portlet using Spring 3.0 for WebSphere Portal 7 using RSA 8.0

Using this article I am trying to document step by step information for creating a JSR 286 basic portlet using Spring 3.0 Portlet MVC Framework on Rational Software Architect v 8.0 and WebSphere Portal Server v 7.0 Following steps are divided broadly into three sub-section :

Setting up RSA and Creating Portlet Project

Providing Spring Configuration and writing controller

Deploying and testing portlet

Setting up RSA and Creating Portlet Project :

1. Select New Project; select the option to show all wizards at the bottom to show portlet project option.

2. On the next screen put the project name and un-check option to create a portlet.  Also create a new EAR Project if you don’t have any existing in your workspace. 

3. Upon completion of the above step you should following structure created in you workspace:

4. Import Spring Jar files to EAR Assembly. To import Right Click on EAR Project, go to Import Option and select Java EE Utility Jar . You will see following screen:

5. Now import following Spring JAR files. Chose option to copy utility jars into the EAR project. You can download these library file from Spring WebSite:

·         org.springframework.aop-3.0.0.RELEASE.jar

·         org.springframework.asm-3.0.0.RELEASE.jar

·         org.springframework.beans-3.0.0.RELEASE.jar

·         org.springframework.context-3.0.0.RELEASE.jar

·         org.springframework.core-3.0.0.RELEASE.jar

·         org.springframework.expression-3.0.0.RELEASE.jar

·         org.springframework.web-3.0.0.RELEASE.jar

·         org.springframework.web.portlet-3.0.0.RELEASE.jar

·         org.springframework.web.servlet-3.0.0.RELEASE.jar

At this point, you have setup your project successfully. 

Providing Spring Configuration and writing controller :

1. Now first write a test controller for Spring Portlet.  Following is a very basic controller which just forward control to the welcome page after being called.

 2. Providing Spring Configuration:

Application Context Configuration

Add application level configuration file, whose entry is usually provided in web.xml. This file is used for declaring application level beans and configuration. For this sample we do not have any, so leaving it blank

Make Following entry to web.xml

Portlet Configuration :

You need to provide information about the handler, your controller and view resolver you are using. Add following Spring configuration for the portlet :

Make an entry into portlet.xml

At this point you are done with Spring configuration and basic portlet code for the sample portlet. 

Deploying and Testing Sample Portlet 

Now add this EAR to Portal Server and publish it. 

Now hit the browser http://localhost:10039/wps/myportal/ [ FOR WPS 7.0 ] and you would see the welcome message of the portlet.

This article describes setting up and testing a basic JSR 286 Portlet implemented using Spring 3.0 Portlet MVC on WebSphere Portal 7.0 using Rational Software Architect. 

Hope this helps--

Download the Source Code

[gauravdaga]

Play with HTTP Status code : Handling Exception in AJAX Calls in Portlets and Servlets

As the Web Application are getting richer day by day, implementation complexity also increased proportionality. When you make a AJAX call and in case any application exception occurs at server while processing your request then How would you handle it at the client browser..? As script executing at browser is not in position to detect real-time status for server side processing. We can not scripts intelligent enough to detect error/success at server processing.

To overcome this challenge, I used setting up status code for HTTP Response, I am preparing. To know more about the HTTP Status code have a look at this link. Basically there are some standard (reserved) codes which are used by HTTP and there is range of numbers which are not being used by current HTTP version. So while sending response from the server, you can pretty much use one of these non-used status code and at script level check for the response with specific status code. So when exception has occurred at server side while processing your request, you can pretty much write error specific information and set pre-standardized status code before writing the response to browser stream. 

When you are working for portlets you can use following method of javax.portlet.ResourceResponse to set the status code :

    ResourceResponse.setProperty(ResourceResponse.HTTP_STATUS_CODE, "477");

                ResourceResponse.getWriter().write();

Where

477-- Status code pre-defined.

StringObjectRepresetingResponse -- Response which you plan to write on the output stream.

When you are working with Servlets, you can pretty much use following method:

   javax.servlet.HttpServletResponse.sendError(int sc,String msg)throws IOException

  javax.servlet.HttpServletResponse.sendError(int sc)throws IOException

At the scripting level, you can detect status code as below:

If you are using Plain JavaScript (no library like dojo, jquery etc)

          var req;

          function makeAJAXCall(){

if(typeof XMLHttpRequest != "undefined") {

req = new XMLHttpRequest()

} else if (window.ActiveXObject) {

req = new ActiveXObject("Microsoft.XMLHTTP");

} req.open("GET", <URL TO BE REQUESTED>, true); req.onreadystatechange = handleResource; req.send(null); } function handleResource(){

if (req.readyState == 4) {

     if (req.status == 200) {

      // Handle success case, put logic whatever you want

     }

     else if (req.status == 477) { // custom header code

       // Handle response accordingly..

     }

     }

      }

In case you are using dojo, probably you can write your error handler for dojo.xhr as follows:

handleErrorResponse:function(errorText,ioargs){

if(ioargs.xhr.status == 477){

//When Error will come in handle JSON scenario,it might fail

}

}

      },

It works perfect. This pointer leads to make your scripting in more intelligent way.. for example is script is expecting a HTML response and during processing request you realize that server should send the response not as HTML rather as XML or JSON then you while sending response you can set pre-standardized custom status code.. and appropriate script block would be invoked. So I think I am good to play with HTTP Status code.. let's play with HTTP Status code.. :) 

Please note: that when you are using servlet response's sendError method, response message is translated to HTML by App Server as per the servlet specification. In case you are sending HTML content, then it will not be a problem but in case you are sending a JSON/XML response with erroneous status code then you will have to put extra logic at script level to parse HTML Content and extract your JSON/XML Response.

[gauravdaga]

Article: Implementation approach for Spring Framework in WebSphere Environment

Below here is the nice article I found for Spring Integration with WebSphere. Team of experts has suggested approach for the best practices when you are planning to use Spring on WebSphere Environment. Sharing here, probably it can help you :

http://www.ibm.com/developerworks/websphere/techjournal/0609_alcott/0609_alcott.html

This article also talks about possible security leaks in Spring framework which worth considering while making a choice on Framework for your application. Though this article does not talk much about Spring Integration with WebSphere Portal, but general J2EE Technic can be adopted. I will try to share my experience on Spring Portlet Framework which I am focusing currently.

[gauravdaga]

J2EE Design Patterns

For a programmer, knowledge of programming language is equally important as of design pattern. If you have good understanding of design pattern, then you wont have much trouble in understanding any complex application.. at the same time if you are designing solution for your problem this knowledge will help you design better solution.. in turns longer lifetime of the application. On Sun;s website, there is one good tutorial covering this book only, click here to go to the tutorial. Link mentioned is a book covering various design patterns used in J2EE technologies.. I likes this book and thought of sharing it. If you want to see the book here.. then also I tried little my scripting knowledge and tried embedding book here itself. function sayHi(){document.getElementById('a1').innerHTML='<iframe frameborder="0" scrolling="no" style="border:0px" src="http://books.google.com/books?id=1dx34EMVyi8C&lpg=PP1&dq=Core%20J2EE%20Patterns%3A%20Best%20Practices%20and%20Design%20Strategies&pg=PR26&output=embed" width=500 height=500>';document.getElementById('a1').style.display='block';} Click Me to continue reading here only