On 3/25/2010 10:31 AM, Jon Stevens wrote:
I don't mind using JSP's for some of the (separated) control logic.
For example, you have a form action:
<form action="email_confirm_submit.jsp">
Inside of it, it looks like this:
http://code.google.com/p/subetha/source/browse/trunk/web/email_confirm_submit.jsp
That said, look at that code. The logic for determining the next page
to redirect to is either in the <t:action> or within the JSTL within
the email_confirm_submit.jsp. Generally, it is nice to have it in JSTL
because a UI person can change the location of the final page without
having to modify java code to do so.
The point being that by the time you get to the view layer (ie: a jsp
that doesn't have _submit.jsp at the end), you don't do a redirect.
You are depending on what is effectively a bug in Resin that has now
been fixed in a newer version. You should modify your code to change
that dependency because you can (and should) be doing it differently.
jon
On Thu, Mar 25, 2010 at 8:18 AM, Aaron Freeman
<aaron.free...@layerz.com <mailto:aaron.free...@layerz.com>> wrote:
It's not in the view layer. We segregate our controller JSPs from
our view JSPs. So you will change your argument to say that we
should not use JSPs at the control layer, and of course _most_ of
our control logic is in pure Java, but there are cases where
having our controller logic written in JSTL (and separated from
other model/view JSP pages) is a substantial advantage for us.
So the question still stands, is there a global way to change the
commit point so we don't have to constantly reset a connection to
clear the buffer?
Aaron
On 3/25/2010 10:02 AM, Jon Stevens wrote:
This is why you don't put application logic into the view layer.
Before you 'push' your data into the view, figure out if you want
to do the redirect or not.
jon
On Thu, Mar 25, 2010 at 7:49 AM, Aaron Freeman
<aaron.free...@layerz.com <mailto:aaron.free...@layerz.com>> wrote:
We take some fairly lengthy queries (lengthy row based on row
count), and push the data into hashmaps in JSTL pages. After
that sometimes we evaluate the hashmap and sometimes have to
redirect the request to another page. In 3.0.23 it works
with no problems. In 4.0.5 we get
"java.lang.IllegalStateException: Can't sendRedirect() after
data has committed to the client."
The reason being, that the for loop is causing a ton of white
space to be sent to be buffered up, and at some point a
buffer size limit has been hit with only whitespace, causing
Resin to then send the HTTP headers and commit the request.
So in the for loop I can do this to "fix" the problem:
<c:forEach items="${requestScope.getRewriteUrlsQuery.rows}"
var="rewriteUrlsQuery">
<% response.reset(); %>
....
</c:forEach>
The question is, is there a setting in the resin.xml where I
can change the buffer size globally, or do we have to go to
modify all JSPs that potentially have this problem? Was the
default commit point changed between 3.0.x and
4.0.x, or some other architecture change, as we have never
seen this until now?*
*
Thanks,
Aaron*
*
So the code example, from a style stand-point, is almost spot on with
how have laid our model/view/controller JSPs. I don't know what a t:
library, is but I am sure its some custom way to call your model code.
We do a <jsp:include> instead, but it's stylistically the same -- the
model is separated from your example controller.
In a JSP-based controller we are parsing the results of the model data
into a hashmap and then processing the elements in the hashmap to
determine if we need to redirect before we call the view. So our
controller looks like:
<jsp:include page="/model/grab-data.sql"/>
<%-- Process the results of the model --%>
<c:forEach items="${requestScope.hashMap.values()}" var="rewriteUrlsQuery">
....
</c:forEach>
<c:choose>
<c:when test="${redirect == 'true'}">
<c:redirect ...>
</c:when>
<c:otherwise>
<jsp:include page="/view/..."/>
</c:otherwise>
</c:choose>
So I am not quite tracking with you on what we need to differently in
our controller? We are trying to do a redirect before we get to the
view layer, as you suggest, and as your code is suggesting.
Right or wrong, this is a style we have used in several places, and
instead of modifying a lot of code it would be much easier if we can
simply change the buffer size commit point. We definitely didn't intend
to exploit a bug, we are just trying to follow easy to maintain good MVC
practices and ran into this hiccup.
Fortunately through all of our testing this is the only show stopper for
us from rolling out to the newest version of Resin 4.0.5 with our
existing code base.
Thanks for you help,
Aaron
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