I agree that this could be done elegantly without requiring the use of a
directive in the conf. files. But the issue I was addressing was
out-of-the-box use of servlets which could be available as components... in
this case, it would be beneficial to be able to chain them in some optimal
way without having to write code...
rajesh
> -----Original Message-----
> From: jon * [mailto:[EMAIL PROTECTED]]
> Sent: Monday, March 29, 1999 7:24 PM
> To: Java Apache Users
> Subject: Re: Chaining in JServ
>
>
> >>There are better ways to chain servlets...it is called
> >Class.forName().
> >
> > How??? Could you elaborate on this??
>
> some semi-pseudo code to get you into the picture...the idea
> being that you
> can dynamicially execute another "servlet" that implements
> the ServletChain
> interface.
>
> public interface ServletChain
> {
> public void execute (HttpServletOutputStream output);
> }
>
> ServletChain chain = null;
>
> String servletToExecuteNext = "myservlet";
> Class aClass = Class.forName ( servletToExecuteNext );
> chain = (ServletChain) aClass.newInstance();
> chain.execute( output )
>
> I'm working on an open source framework rightnow that
> mirror's the ideas of
> Stefano's excellent Cocoon servlet but instead keeps
> everything in Java by
> using the above approach to dynamicially load the next class
> in the chain.
> Imagine having a set of "templates" that just loads and
> executes the right
> files depending on what was requested in the HTTP GET/POST
> arguments. Not
> only that, but you can cache the result of the Class.forName
> line so that
> you only need to do that once (even though there isn't a very large
> performance penalty in Class.forName()).
>
> I have been using a framework like this for 2+ years now and
> it is the most
> flexible way to do things. I have one main "servlet" that
> simply loads and
> executes classes that implement the various interfaces. This
> has benefits of
> things like a single point to throw exceptions to as well as
> a single entry
> point for security control. It is also very easy for multiple
> developers to
> work on portions of the same project at the same time because
> all they have
> to do is work on a single "module" that implements the well defined
> interface.
>
> > How would it handle chaining servlets as in a piped
> chain... I think that
> > the ability to pipe output between servlets is a pretty
> good feature...
>
> It is good to chain servlets, but not as a piped chain. This
> is something
> that is extremely confusing to users and is very limiting in
> that all you
> can modify is the output of the previous servlet. Why not use
> the above
> approach to extend the "ServletChain" interface and make things more
> scalable and dynamic?
>
> -jon
>
>
>
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