I describe this in more detail in the book, but my take on this is that Struts and JSF are focused on different parts of the application. They also overlap in some areas, however, which is probably the cause for this endless discussion.
In particular, I've noticed that a simple "hello world" application with two screens (paint form and respond to POST) looks very similar in JSF and Struts, at least on the surface:
- Form beans are "model objects" in JSF
- both Struts and JSF have their own tag library for defining HTML form fields. (at first glance the main advantage of JSF is having validation inline with HTML form tags)
- you have FacesServlet instead of ActionServlet
- navigation rules instead of action-forwards
- ApplicationHandlers and EventListeners instead of Actions
JSF has a much more robust component and event handling model, though, which makes it more like a "real" GUI framework to work with. (Struts is almost like a base case of JSF, with only one type of event.) The advantage is that JSF is better suited for dealing with more complex UIs where you have lots of components with independent state to manage.
Here's one example of something that should be much easier with JSF than Struts: Imagine a page with three sortable tables. When you click a header on table #1, the page reloads, re-sorting table #1. But the current sorting on tables #2 and #3 should remain constant. This is obviously possible with Struts, but requires you to futz with URL vars somewhere or rely on session scope. JSF insulates you one layer from all that, providing component state management as part of the framework.
The _disadvantage_ to JSF is that when your UI is *simple* (closer to hello-world in complexity), JSF seems to be more work to deal with. I've found that the insulation from the details of HTTP/request-response makes doing simple things much more difficult, while Struts is more gentle-slope. You don't have to use Tiles and Validator right away, and there's an obvious, easy path to migrate an ad-hoc/Model 1 servlet or JSP to Struts.
-- Bill -- Bill Schneider Chief Architect
Vecna Technologies, Inc. 5004 Lehigh Road, Suite B College Park, MD 20740 [EMAIL PROTECTED] t: 301-864-7594 f: 301-699-3180
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