Extending Struts Tags

Hi All,

i am using struts 2 for our current project, to implement field level security. I have to extend the Struts general componet Tags to implement additional features. I dont know where to start. Can you please provide me with an example to do this would help me lot.

For Eg. I have a text box it should be displayed as Read Only for certain users, Editable for certain users and label for some users. So i am planning to pass role as input parameter, which will decide to dispaly the field accordingly.

Thanks in Advance.