Java EE (Java Enterprise Edition) General Discussion

in html we can call a user define function at any event and include the function within <script> </script>.
eg:
<script language="javascript">
<!--
function GetData() {
// do something
]
-->
</script>
.
.
.
<input type="submit" text="submit" onclick="GetData()">


but how are we going to call the function GetData() in jsp ..... are we using this tag <% %> ?? how does the syntax like ??

Please assist... thanks