July 6, 2004

The AOP panel at JavaOne was a big success. Maybe it was because of the provocative title ("AOP : The next big thing or giant leap backward"), which was concocted by the mischievous Graham. Maybe it was because James draws a lot of attendance. Or maybe, just maybe, it's that more and more people are getting extremely curious about AOP.

The panel was moderated by Simon Phipps and featured:

• Gregor Kiczales, as the "father of AOP".
• Graham Hamilton, as "the skeptic".
• Myself, as the "Conflicted AOP advocate"
• James Gosling, as... well, himself.

Somebody told me after the panel that not only was the main room full, but the overflow room was standing room only, which probably adds up to an audience of 2000-2500 people.

Simon opened the debate by asking a quick show of hands asking how many people had already heard of AOP, and I estimate that 90% of the hands came up. When the question was refined to "Who has used AOP?", a great deal of hands went down but quite a few remained up.

Gregor opened the debate by a ten-minute introduction on AOP, which is quite a tour de force. Using a simple application drawing shapes, Gregor quickly showed how concerns get scattered into your code, what aspects and pointcuts are and how they can help you write cleaner code.

Graham raised concerns about the loss of simplicity seen in the approach offered by AOP. He said that throughout the years, Sun has gone to great lengths to keep the language simple, but with AOP, a simple Java line such as "a = b * foo()" no longer means what you think it means.

When my turn came, I explained the reason for my internal conflict. In short, I see a lot of potential in AOP but I still perceive it as extremely complicated and representing a steeper learning curve than most Java developers are willing to climb. I will expand on these ideas in a separate blog entry.

Finally, James offered his ideas on AOP, starting by his very simple opening: "I like AOP a lot". His concerns are a bit different from Graham's, though: James is more afraid of the paradigm shift represented by AOP while we are just barely getting used to OOP.

The panel went by really quick and unfortunately, I don't remember most of the questions we were asked (except one likening AOP to Lisp, which offered many features similar to AOP, especially Lisp dialects that offered a Meta-Object Protocol).

I have the feeling we achieved something important last week. There was no bickering about technical details on AOP frameworks nor any personal agendas pushed in outrageous ways. It was a simple exchange of views from people genuinely interested in helping developers write better code,

If anything, we showed the audience that AOP was taken very seriously and considered in very pragmatic terms by a lot of people these days. Whether you think you will be using AOP in your work or not, I strongly recommend you take some time to study its major concepts. I guarantee that even if you day job is to write C code, you will end up reusing these concepts in your own way and your code will greatly benefit from it.

About the author