[aosd-discuss] AOP and Modern OO approaches

[Donisthorpe C (AT)]

Dean,
 
Your suggestion that 'its a paradox that modularizing global, cross-cutting behaviours require very fine-grained control' is  interesting and prompts the following thought.  
 
It would be more efficient to limit the effect of cross-cutting behaviours and reduce the overhead of 'fine-grained control' in the software.  This would have the benefit of simplifying the software development task. It could be simplified if crosscut influence were minimised or constrained at the system level prior to software design.
 
I think that crosscuts can be tackled at different levels in the development process and that early identification can make the detailed design task easier.   EA could simplify the system architecture and reduce the need for crosscutting effects by identifying and developing the headline aspects.  
 
Perhaps, this analysis approach could be enhanced to help reduce the possibility of system failure as not all crosscut effects can be predicted within a large complex system.
 
 
Regards
 
Charles
 

________________________________

From: discuss-bounces at aosd.net on behalf of Dean Wampler
Sent: Wed 09/05/2007 14:07
To: vamsidhar sharma
Cc: discuss at aosd.net
Subject: Re: [aosd-discuss] AOP and Modern OO approaches



Since I wrote the presentation, perhaps I should field the question ;)

All I meant by this statement is that AOP expands the options for 
changing program behavior at the level of the class, individual 
objects, and even individual methods and fields in an object. The OO 
mechanisms you mention take you most of the way and they are great 
when you can choose which subclasses to define and instantiate. Then 
you can override methods as needed to change the behavior locally.

You don't always have that freedom in some real-world systems, so 
it's nice to have tools with sophisticated "join point models" that 
let you reach into existing classes and objects and modify their 
behavior, even dynamically. The better AOP tools let you specify 
conditions for when this behavior should occur. For example, you can 
say that "new behavior" N should only be added to a particular method 
M if it is being called in the context of another method M1 and data 
D has a particular value, etc., etc.

However, the important point isn't that you have more fine-grained 
control over the objects in the system. Rather, the important point 
of AOP is that you can specify in one place (a "module") the state 
and behaviors you want that are shared among an arbitrary number of 
classes and objects that might not have any other relationship.

Perhaps it's a paradox that modularizing these global, cross-cutting 
behaviors requires very fine-grained control.

Hope this helps.

Dean

On May 9, 2007, at 5:55 AM, vamsidhar sharma wrote:

> While understanding AOP I found this article by Robert Martin
>
> http://objectmentor.com/resources/articles/AOP_in_Ruby.pdf
>
> In this the author says that modern OO desgin approaches like 
> inheritance, design patterns, Inversion of control containers etc. 
> work at a coarse grained level of interaction..
>
> Can anyone clarify what that means.. the coarse-grained level?
>
> Thanks
> Vamsi
>
>
>
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Dean Wampler, Ph.D.
dean at objectmentor.com
http://www.objectmentor.com <http://www.objectmentor.com/> 
http://www.aspectprogramming.com <http://www.aspectprogramming.com/> 
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