This post originated from an RSS feed registered with Java Buzz
by Ted Leung.
Original Post: SeaJUG 9/20/2005
Feed Title: Ted Leung on the air : computers/programming/java
Feed URL: http://www.sauria.com/blog/computers/programming/java?flav=rss
Feed Description: Ted Leung on the air: Open Source, Java, Python, and ...
It's been quite sometime since I made it to a SeaJUG meeting. Jayson Raymond, our host, mentioned that SeaJUG's 10 year anniversary is coming up, but I haven't been gone quite that long. It's just that SeaJUG is (apparently -- I'm not up on JUG lifetimes) one of the older JUGs. In fact it's been so long that I didn't even know that we were meeting in a new location. Normally I ride over with a friend who lives in Seattle, but he wasn't available, so a bunch of us from Bainbridge piled into a car and drove over.
Last night's meeting was a presentation by Ramnivas Laddad on "What's new in AOP". This was our yearly preview presentation ahead of the excellent Pacific Northwest Software Symposium. Several years ago I did a SeaJUG presentation on AspectJ, and I was curious to see how much things have changed.
There are now more syntaxes for expressing pointcuts and advice. You can have your choice of AspectJ syntax (nice because the AspectJ compiler can verify your pointcut expressions), Jave 1.5 annotations (nice because you aren't learning a special syntax, except that you are because you have to learn the mini-language for specifiying pointcuts), and even an XML based syntax (handy for instantiating abstract aspects at deployment time).
Also, you can now write pointcuts that rely on JDK 1.5 metadata. This is controversial. You get more control if you limit your pointcuts to annotations, but then you have to add annotations, which goes against the AOP idea of not having to modify the crosscut code.
The tooling has improved a lot. There's now very decent support in Eclipse (and some other IDE's), and that support does cool stuff like show you all the advised methods and so forth. There's also a history view that lets you view how aspects have been added or removed to parts of the system over time -- a nice usability improvement would be the ability to do this between revisions in the version control system.
When I gave my presentation, we had a long discussion about applications of AOP. I wish that there had been more discussion about this topic. It's easy to see the application of AOP to systems types of concerns, logging, performance testing, security, transactions, and so forth. It would be nice to see some patterns of aspect use as it relates to problem domains. Of course, the whole field is still pretty new, so it's understandable that there isn't a lot of data about this just yet. One interesting usage the was discussed was to advise constructors or factory methods as a way of injecting mock objects for use during unit testing.
I'm not doing a lot of Java these days, but I like to keep my nose in what's going on. As I was listening, I was thinking about having some of these capabilities in Python. Of course, you can do a lot of AOP style things fairly easily in Python, because various kinds of interception are easy to do. The things that I think are really missing are the pointcut expression language for expressing where interception is to take place, and whatever runtime support is needed to do the weaving. It sure would be handy...
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