Hm, to check for the global version of the JSF implementation they already check for existence of Application.getExpressionFactory() That still does not answer the question if a particular component class is JSF 1.1 or 1.2. (Is it really possible at all to run a 1.1 component library on a 1.2 implementation?) Unfortunately UIComponent has default implementations for the new 1.2 methods that try to supply reasonable behaviour, e.g. getValueExpression() instantiates a ValueExpressionValueBindingAdapter. So one cannot check for methods in the component's class. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4071768#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...