Can WebLogic do Servlet chaining?

Question

Is there any way to do servlet chaining, or more specifically, for a servlet
          to process the output of another servlet efficiently in WebLogic?
          Sure a servlet can make another HTTP request on its own servlet engine but
          that seems way too inefficient and heavy handed.
          J.
          James Strachan
          =============
          email: [email protected]
          web: http://www.metastuff.com
          

Answer 1

Check out XSPs from cocoon. xml.apache.org
          -- bk
          James Strachan wrote:
          > JSP includes go straight to the HTTP response - there's no way of
          > redirecting them to some internal buffer for post processing. (*)
          >
          > I'd like to be able to do simple Servlet chaining at the Servlet or JSP
          > level. i.e. I want to post process the output of one servlet / JSP page to
          > do things like caching or XSL styling. This is a totally reasonable request
          > IMHO. Imagine a complex portal with alot of included JSP files - I'd like to
          > be able to cache whole chunks of the page - a chunk may have many includes
          > inside it..
          >
          > Right now there is no way of doing such a thing in WebLogic AFAIK. You have
          > to go through every JSP file and add caching / styling to it rather than
          > being able to 'pipeline' or 'servlet chain' which is less than ideal. (Also
          > remember there is a 64K code size limit on the bytecode that can exist in a
          > Java class - so JSP files should be kept small to void hitting this
          > barrier). I can't quite believe noone else has hit this problem.
          >
          > There are workarounds such as to do the include using seperate internal HTTP
          > requests, RMI calls or JMS messages all of which seem to be far too
          > heavyweight.
          >
          > (*)
          > <aside>
          > One side effect of the JSP include always going straight to the response
          > means that you can't use WebLogics <cache> tag if you are using any kind of
          > JSP include. e.g. the following snippet doesn't work as expected :-
          >
          > <cache>
          > something
          > <jsp:include file="foo.jsp" flush="true"/>
          > something else
          > </cache>
          >
          > since you are not allowed to do an include inside a body tag,. Even if you
          > were the output of the include goes straight to the response, not the body
          > tag.
          >
          > So you have to close and reopen the cache tags around each include which may
          > break your XML complience for complex pages and is error prone and much more
          > inefficent to boot:-
          >
          > <cache>
          > something
          > </cache>
          > <jsp:include file="foo.jsp" flush="true"/>
          > <cache>
          > something else
          > </cache>
          >
          > </aside>
          >
          > --
          > J.
          >
          > James Strachan
          > =============
          > email: [email protected]
          > web: http://www.metastuff.com
          >
          > "Jaggu Dada" <[email protected]> wrote in message
          > news:[email protected]...
          > >
          > > Hi --
          > >
          > > Why not use JSP includes? The only servlet "chaining" that is
          > > reasonable
          > > is to use a servlet to process an initial request, and make some
          > > decision
          > > (based on the querystr, for example) then, without having written
          > > anything
          > > back to the client, do a server side redirect (with RequestDispatcher)
          > > to
          > > a servlet or JSP that does some work. If I understand you correctly,
          > > servlets
          > > were not designed to do what you are proposing.
          > >
          > > Hope this helps,
          > >
          > > -jaggu
          > >
          > > James Strachan wrote:
          > > >
          > > > Hi Joe
          > > >
          > > > Thanks for that. Sure that would work too though its probably a heavier
          > > > weight than just plain old HTTP.
          > > >
          > > > I was looking for something a little more lightweight such that I could
          > > > include 10-20 servlet chains per web page on a complex portal without
          > too
          > > > much performance hit. i.e. using synchronous servlet 'pipelining' to
          > > > generate complex pages without having to do many internal HTTP / JMS
          > > > requests.
          > > >
          > > > --
          > > > J.
          > > >
          > > > James Strachan
          > > > =============
          > > > email: [email protected]
          > > > web: http://www.metastuff.com
          > > >
          > > > "Joe Trung" <[email protected]> wrote in message
          > > > news:[email protected]...
          > > > >
          > > > > Hi Jim,
          > > > > I chain my servlets via jms: the queue is output/input bin
          > > > >
          > > > > Joe
          > > > >
          > > > >
          > > > > "James Strachan" <[email protected]> wrote:
          > > > > >Is there any way to do servlet chaining, or more specifically, for a
          > > > servlet
          > > > > >to process the output of another servlet efficiently in WebLogic?
          > > > > >
          > > > > >Sure a servlet can make another HTTP request on its own servlet
          > engine
          > > > but
          > > > > >that seems way too inefficient and heavy handed.
          > > > > >
          > > > > >J.
          > > > > >
          > > > > >James Strachan
          > > > > >=============
          > > > > >email: [email protected]
          > > > > >web: http://www.metastuff.com
          > > > > >
          > > > > >
          > > > > >
          > > > >