Never POST to JSP

[M. Gagnon]

Bear,

In a response to someone else's question about using beans vs. servlets you answered:

"That's an easy one: never submit a form to a JSP. Period. JSPs should be restricted to creation of the view; all processing should be done in a servlet controller."

I have a demo web site for buying concert tickets. The shopping cart is quite simple in that one does not "browse" the site for different items to buy, but views one page of concerts and opens a ticket order that is sequential -- first the customer chooses the concert(s), then enters personal and payment info and finally confirms the order. The first pages submit form data to the next JSP and the order isn't submitted to a servlet until the customer confirms that all the data entered is correct. This design makes sense to me. Why add another layer of complexity/processing when all I'm doing in the first steps is storing data in a bean that isn't submitted to the database until the final step? I really can't think of a good reason to use a controller servlet in the first steps. If you can, please let me know.

Thanks,
m. gagnon

[Bear Bibeault]

The camel's nose and all..

It's very rare that a posted form's data can be used on JSP page without any processing whatsoever. If it is true, in your case, that the JSP is still only a pure "view" element, then while I would personally still go through a controller (because, sure as hell, as soon as I finish, some requirement that adds processing to the data will come up), then I'd say that posting to the JSP in this case would not be an architectural violation. But I caution that that's a slippery slope. So I reiterate: never send data directly to a JSP -- it's just too easy to fall into a trap.

[Ken Robinson]

I have had this situation before. Usually I keep a JSP and do not add a Servlet just to forward the request, but I register the JSP as a <servlet> in web.xml (use <jsp-file> instead of <servlet-class> ) and give it a mapping consistent with the servlet I would have created in normal circumstances. This way everything fits in a standard way, it's easier to add a servlet in the middle if requirements are added and I just feel better about it. I'm not a fan of having the HTML the client sees send to a JSP.
[ July 21, 2004: Message edited by: Ken Robinson ]