Using JSP scriplets in the JSF tags

Question

Hi,
I haven't done that much JSP development using various tag libraries prior to looking at JSF, hence this very basic question:
I am declaring and manipulating Java variables in my JSP. Is there a way to access those in my JSF tags? It seems that something like:
<%
String myString="MyLabel";
%>
<h:view>
<h:outputText id="myID" value="<%=myString%>" />
</h:view>
blows up in the JSF processor.
I am porting some stuff to JSF and hence do not use backing beans in all cases.
Any suggestions/ideas/pointers are greatly appreciated.
Thanks in advance,
Vadim.

Answer 1

JSF action element attributes take JSF EL expressions, not Java expressions. A JSF EL expression has access to objects in one of request, session or application scope only, not to scripting variables. One way to get your example to work is by putting the String in one of these scopes within the scriptlet, e.g.:
<%
  String myString="MyLabel";
  request.setAttribute("myString", myString);
%>
<h:view>
  <h:outputText id="myID" value="#{myString}" />
</h:view>But, if you're porting a JSP-based application to JSF, I strongly recommend that you move all scriptlet code into beans; otherwise it's kind of pointless to migrate to JSF. The strength of JSF is its separation of UI layout and application logic.
Even though JSP happens to be one way to wire up a JSF view with JSF components, JSF has very little to do with JSP. You need to understand the basic JSF component model, event-driven development, and use JavaBeans to really gain any benefits. Don't be fooled into believing that JSF is "just a new JSP tag library" by the support for JSP as the default presentation layer; it's far more than that, and I personally believe that using JSP as the presentation layer makes using JSF a lot harder than it should be. In fact, most of the issues posted in this forum are issues with the JSP layer, not with the core JSF components or the infrastructure classes.
Hans Bergsten (EG member)