how to download a file using JSF

[Nutulapati, Krishna]

Hello All,
Can any one help me on how to  download a file into client system using
JSF. 
Soon after user clicks on download button on the webpage, some thing
like   File Chooser papers,user selects the file and clicks the save
button. 
File should be saved into the client system at specified location. Any
samples or examples with JSF/Backing Bean  would be very helpful. 
 
Environment:- JSF, SPRING , WEBSPHERE 6.1 RAD 7.0
 
Thanks
Krishna