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From "Craig R. McClanahan" <craig...@apache.org>
Subject Re: [Design Discussion] DynaBean - JavaBeans with dynamic properties
Date Sat, 15 Dec 2001 22:39:53 GMT


On 15 Dec 2001, Bryan Field-Elliot wrote:

> Date: 15 Dec 2001 15:21:05 -0700
> From: Bryan Field-Elliot <bryan@netmeme.org>
> Reply-To: Jakarta Commons Developers List <commons-dev@jakarta.apache.org>
> To: Jakarta Commons Developers List <commons-dev@jakarta.apache.org>
> Subject: Re: [Design Discussion] DynaBean - JavaBeans with dynamic
>     properties
>
> It seems to me that Java was built from the start to be strongly-typed
> and compilation-centered. This follows in the strong tradition of C++
> and C.
>
> In contrast, languages such as Python (over which I am admittedly
> intruiged, but definitely no expert) are weakly-typed, and
> scripting-centered.
>
> Recently, the Java community has taken steps to move away from those
> core principles of Java -- in terms of moving away from being
> compilation centered, we have mechanisms like JSP, whichs seems to be an
> extremely complex layer on top of classical Java just to achieve that
> "dynamicness" (can anyone say that the Catalina JSP effort was trivial
> or obvious)?
>

It's somewhat amusing to note that the reflection APIs in Java (which IMHO
is just as much a distringuishing factor as anything else) have been
around just as long as the JavaBeans design patterns have.  It's hardly
"revolutionary" to leverage such capabilities in web apps, when it has
been used to very good effect in GUI apps and tools for a *long* time.

I'm not quite sure I understand your point about the "Catalina JSP
effort", but (being one of the core Tomcat developers) I'm interested in
hearing more about how you think it's applicable to this discussion.

> Now we are groping with limitations in strongly-typed development,
> coming up with things like the DynaBean. Again, we are introducing
> layers on top of classical Java in order to achieve development patterns
> not compatible with Java's original design principles (strong typing).
>
> It seems to me that if good patterns in web app design require these
> language traits, then perhaps the choice of language itself needs to be
> re-evaluated?
>
> Or, on the other hand, perhaps these design patterns need to be
> re-evaluated (e.g. do we really need a Dynamic Bean?), and instead, come
> up with new design patterns for web app development which are not only
> compatible with, but greatly benefit from, the language being
> strongly-typed.
>

Seems to me we already have that.  What I want to support, and what Struts
(I'm also the primary author of Struts <http://jakarta.apache.org/struts>)
have wanted for a long time, is the abillity to go beyond static typing
for certain use cases *without* having to throw away everything they
already have learned and built.  Fortunately, Java accomodates that for us
quite nicely.

> Perhaps I'm over the top here. I'm really just trying to stir up a
> little discussion. But it seems to me that JSP, and now the DynaBean,
> represent a whole lot of work to try to hammer a square peg through a
> round hole.
>
> Thoughts and discussion appreciated,
>

The discussion ought to be interesting!

> Bryan


Craig



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