Populate the values at runtiime on some value selection - JSF

In JSF, if you select a value from drop down box and depending on this value if you want to forward a request to server and populate related other values on the screen.
This can be handled with the following example

If my screen shows following fields on the screen
1. drop down of student's roll numbers
2. Text box for student's name
3. Text box for student's class
4. Text box for student's address

Information is stored in database in 'STUDENTS' table.

On selection of student's roll number, to populate the other fields my code will look like


<h:outputtext id="rollNumberLbl" value="Roll Number">

<h:selectonemenu id="rollNumComboBx" styleclass="normalTxtBox" value="#{studentBean.rollNo}" valuechangelistener="#{studentBean.getStudentByRollNumber}">

<f:selectitems id="rollNumList" itemvalue="#{rollNum.rollNo}" value="#{studentBean.rollNumbersList}" var="rollNum">

<a4j:support ajaxsingle="true" event="onchange" rerender="studNameTxt,studClassTxt,studAddrTxt">

</a4j:support>



<h:outputtext id="nameLbl" value="Student Name : ">

<h:inputtext id="studNameTxt" value="#{studentBean.studentName}">



<h:outputtext id="classLbl" value="Student Class : ">

<h:inputtext id="studClassTxt" value="#{studentBean.studentClass}">



<h:outputtext id="addrLbl" value="Student Address : ">

<h:inputtext id="studAddrTxt" value="#{studentBean.studentAddress}">





</h:inputtext></h:outputtext></h:inputtext></h:outputtext></h:inputtext></h:outputtext></f:selectitems></h:selectonemenu></h:outputtext>