On Tuesday 01 April 2003 02:30 pm, Thorin Linderholm wrote:
> I have been tasked with porting an existing web application with it's own
> proprietary controller architecture to using Struts.
>
> As they are both web controller architectures, they have many similarities,
> but I'm running into one difference in overall architecture that I'm having
> difficulty resolving.
>
> This difficulty is most closely related to the 'action chaining' posts I've
> been able to find in the mailing list archives.
>
> Specifically, I have over 400 pages mapped to various actions (our
> controller calls them that, and they're roughly synonymous with struts
> actions.) However, our controller allows specifying a list of actions to
> execute on a per-page, and per-page-set basis. In other words, we can
> assign an action like 'Ensure Session initialization has been
> completed/Initialize session' to every page in the site with a single
> mapping (assuming you've already listed all the pages.) Or you can assign
> it to 90% of your pages if you happen to desire. We have approximatly ten
> actions that happen on between 60-99% of the pages on our site. If we were
> to directly translate this to the struts mapping system we would end up
> having to re-specify those ten actions on most of those 400+ pages,
> creating long action chains for each page (a whole lot of duplication: hard
> to maintain, easy to get wrong, etc.)
>
> So, conceptually, I want to be able to apply a few different bits of logic
> to whole sets of pages. Some of those 'bits of logic' (actions if you
> will,) interrupt the process and forward to a different page (page access
> rules for instance.)
>
> There are several possible solutions that I've come up with, but so far all
> of them involve either hacks, extending struts (which happens to partialy
> eliminate the reason I'm being required to move to Struts, and so isn't
> very favored by my supperiors,) some complicated java inheritance hierarchy
> where I inherit non-related functionality in those ten actions into a set
> of compound actions, each inheriting in the set of functionality we want
> (lame,) or I could implement a 'view preprocessor' of some kind that
> parallels the struts-config and defines processing that I need to do for
> each view page (which requires me to have two completely redundant sets of
> page mappings, and apears to me to obsolete the need for Struts in the
> first place (if we were to ignore it's tag libraries and other helper
> classes which we also already have proprietary equivalents to.)
>
> I'd love to hear from anyone about other possibilities, or (even better,)
> pointers to somebody/some package already solving this problem.
>
> Another way to look at the whole thing: How have other people solved the
> problem of being able to apply a set of page access rules to arbitrary sets
> of pages without having to create a system parallel to struts that
> re-defines every page in the application? Or do people consider a parallel
> system that respecifies every page as the proper design?
>
> Thorin
Ever thought of defining functionality equivalent to your proprietory
"actions" in classes that don't extend the Struts framework and chaining
calls to instances of these classes in your Struts Actions?
This is a static solution as opposed to having struts-config.xml support some
sort of action chaining tags but Struts Actions are only HTTP adapters, and
chaining them violates the spirit of the framework. That's why I think
implementing "chaining" with non-Struts classes is a better idea.
Your "actions" seem to be pretty fine-grained ("Ensure Session initialization
has been completed/Initialize session"). If session in this case refers to
the HttpSession, then they are almost as low-level as the Servlet API (why?).
If they are a business tier concept, Struts should have nothing to do with
chaining them.
Paul
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