example: a controller named ajaxhandlerController
it can receive several ajax request types,
each type should have separate block in the layout xml
in layout for index of ajaxhandler i would write
<mymodule_ajaxhandler_index>
<block some block></block>
</mymodule_ajaxhandler_index>
How do I change from index to save for example if there is $request[‘type’]==”save”; so I can use
<mymodule_ajaxhandler_save>
I would forget about layout XML. An simply instantiate a Core_Block_Html_Template and assign the correct template to using the setTemplate method according the the request type received.