The idea behind modules

["C.F. Scheidecker Antunes" <na...@antunes.eti.br>]

Hello all,

I was reading about modules and I wonder if anyone had ever used them.
As far as I can see by the examples, if you have different modules you still
run only one ActionServlet.

Hence modules seem to be useful only for group programming and bigger 
projects.
Am I right on this?

Thanks,

C.F.

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Re: The idea behind modules

[Craig McClanahan <cr...@gmail.com>]

On 8/11/05, Joe Germuska <Jo...@germuska.com> wrote:
> At 6:18 PM -0600 8/10/05, C.F. Scheidecker Antunes wrote:
> >Hello all,
> >
> >I was reading about modules and I wonder if anyone had ever used them.
> >As far as I can see by the examples, if you have different modules you still
> >run only one ActionServlet.
> 
> It is true that you would only have one ActionServlet, but the
> ActionServlet does very little work in Struts after initialization;
> once an application is initialized, per-module RequestProcessor
> objects do just about everything.
> 
> >Hence modules seem to be useful only for group programming and
> >bigger projects.
> >Am I right on this?
> 
> This is probably right.  After implementing one or two projects with
> modules, I personally found that they don't fit my team's development
> style.   My feeling is that the original design of modules was for
> software components that were pretty independent of each other, and
> there are pretty substantial "walls" between modules.  Yes, they
> share the same ServletContext, but Struts tries to isolate modules
> from each other, where I was frequently looking for more integration.
> 
> Personally, once I realized that you can use any number of
> struts-config.xml, tiles-definition.xml and validation.xml files
> without using modules, I had no further interest in "making modules
> work" for my projects; the main gain I sought from them was
> decomposing monolithic config files.
> 
> Perhaps someone else can provide a testimonial on why modules helped
> them do something?
> 

There were at least a couple of original motivations for the creation
of modules:

* Cases where the developer wanted to combine several
  semi-independent Struts-based apps into a single webapp,
  so that they could share session state and/or simulate
  "single sign on" type login.

* Cases where the application was so large that naming
  collisions on actions, forwards, and form beans were
  occurring ... modules give you separate namespaces
  for most of these things.

IIRC, Ted Husted has also talked about using individual modules for
each use case (or "story" in his terminology), just as a way to
enforce logical separation and avoid undesirable cross dependencies.

> Joe
> 

Craig

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Re: The idea behind modules

[Joe Germuska <Jo...@Germuska.com>]

At 6:18 PM -0600 8/10/05, C.F. Scheidecker Antunes wrote:
>Hello all,
>
>I was reading about modules and I wonder if anyone had ever used them.
>As far as I can see by the examples, if you have different modules you still
>run only one ActionServlet.

It is true that you would only have one ActionServlet, but the 
ActionServlet does very little work in Struts after initialization; 
once an application is initialized, per-module RequestProcessor 
objects do just about everything.

>Hence modules seem to be useful only for group programming and 
>bigger projects.
>Am I right on this?

This is probably right.  After implementing one or two projects with 
modules, I personally found that they don't fit my team's development 
style.   My feeling is that the original design of modules was for 
software components that were pretty independent of each other, and 
there are pretty substantial "walls" between modules.  Yes, they 
share the same ServletContext, but Struts tries to isolate modules 
from each other, where I was frequently looking for more integration.

Personally, once I realized that you can use any number of 
struts-config.xml, tiles-definition.xml and validation.xml files 
without using modules, I had no further interest in "making modules 
work" for my projects; the main gain I sought from them was 
decomposing monolithic config files.

Perhaps someone else can provide a testimonial on why modules helped 
them do something?

Joe

-- 
Joe Germuska            
Joe@Germuska.com  
http://blog.germuska.com    
"Narrow minds are weapons made for mass destruction"  -The Ex

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