A step back from the bleeding edge

In an earlier post, I blogged about my gamble with using AspectJ. Well, I've been having Eclipse performance and stability problems for a while now, as I've upgraded Eclipse from 3.1.x to 3.2 to 3.2.1 and kept updating my AspectJ plugins. I've had issues with Maven and AspectJ, especially with Corbetura and AspectJ.

For what? Some clever defensive programming ideas (automatic null checking of parameters), a little bit of concurrency help, and a few additional cases.

Much as I liked the automatic null checking, I found increasingly that I was supressing it (with a special annotation) in many cases. In fact, the most useful place for such checking is in bridge code between user application code and the public Tapestry API ... and that's really not a lot of code.

The concurrency support was nice, but expensive. I found that in most cases I could convert to using copy-on-write, threadsafe collections instead. For the couple of cases where I couldn't I put together a utility class to manage the reentrant read/write lock on behalf of other code.

So ... goodbye AspectJ (for the meantime). Positive improvements: shrunk the size of the JAR by about 30% (657K down to 449K), plus no runtime dependency on AspectJ. Everything's running great. No problems.

Dissapointing. AspectJ still has a raft of very important uses, but the cost (in terms of developer frustrations) outweighs the benefits, at least for nice clean, new code like the Tapestry 5 code base.

Tapestry 5 Screencast #2

This one shows how to use built-in Tapestry components, touches on the exception page, transient and persistent properties, and component event handler methods. Along the way, we see just how great it is to be able to change code on the fly! Tapestry 5 Technology Preview #2 -- 20 Oct 2006

The screencast clocks in at about 9 minutes.

For Tapestry 4 users, the two big things to pay attention to:

• Action handler methods, not listener methods
• Action requests send a client refresh, not updated HTML

The latter one is a big change from Tapestry 4, and implies that more data will have to be persistent between requests; the good news is that client property persistence, as well as flash persistence, will be supported fairly soon.

The constant question is: When will it be done? We'll be getting to the point where the other Tapestry developers can join the fun pretty soon, once I get basic forms and input validation working. I can see a useful platform ready in the spring and a final release, with some form of Spring and Hibernate integration, in the summer. Of course, my schedule is anything but fixed and set (I do have to earn a living around all of this!).

By the way, these screencasts are all done in a single take. What you see, complete with me fumbling with System.out.println, was my third full run through.

Page response is really that fast, even in the face of code changes. I'm not editting out pauses or any tricks like that. It's not just fast due to my dual-core monster desktop either; I've seen just as nice results on my more puny laptop. It's going to be hard to work on any other platform where I actually have to restart or redeploy just to see changes to my code!

HiveMind now an Apache Top Level Project

Finally ... HiveMind is now a top level project at Apache. This is great news, because it will allow the team to bring in HiveMind extensions from all over and put them under one roof.

I've been neglecting HiveMind for a while now as I concentrate on Tapestry 5, which is a shame, but unavoidable. Certainly, the people working on it now are quite capable. In fact, as often as not, if you see a clever idea in HiveMind, it was suggested or even implemented by James or Knut or one of the others.

Tapestry 5 Screencast #1

I've just put together a 6 minute screencast about Tapestry 5. It covers creating a new project (using Maven), setting up dependencies and structure, and creating a page template and seeing changes to the live application when you change a Java class.

Tapestry 5 Technology Preview #1 -- 17 Oct 2006

Class reloading is a key feature of Tapestry 5 and is exceptionally important to the stellar productivity Tapestry 5 will enable. Just as people fastened on to the Tapestry 3/4 templating system, I think many people will fasten on to class reloading. Don't be mistaken; there's a lot more to this enchilada than that one feature. But it's a great feature to hook people early on!

The Ajax Experience -- Next Week

Just a reminder that The Ajax Experience is just over a week away.

Jesse Kuhnert and I will be presenting: Tapestry and Dojo: The Peanut Butter and Jelly of the Ajax World:

Dojo is an open source JavaScript library that provides an improved programming model for JavaScript and a suite of client-side tools and widges. Tapestry is an innovative open source client-side Java framework for building componentized web applications. At first glance, these two look like the Odd Couple, but pull back the covers a bit and you'll see a similar event model and design philosophy that makes these frameworks a cinch to put together. Tapestry 4.1 with Dojo brings about client-side Ajax joy without server-side Java pain.

I just got back from ApacheCon 2006, which was a fun time. I got a chance to talk Tapestry with members of the Shale team and with a few Tapestry users; I even demoed some of the new Tapestry 5 features (resulting in a few dropped jaws). Catch me at The Ajax Experience for more of the same! I also got a bunch of speakers hooked on the Hive boardgame.

It's interesting that one of Tapestry's core concepts, that the controller and view are tightly bound together, is a stumbling block for the Struts/Shale folks. They've been forced to deal with this outlandish, awkward, counter-productive separation between their business logic and their presentation/output for so long you can just see the gears gnashing together when thinking of something else, something that doesn't require tons of tedious coding and configuration. I'm in the process of adding some "Tapestry for Struts Programmers" documentation to the Tapestry 5 site, to try and outline the issues with action frameworks, and the solutions Tapestry offers.

Tapestry: A Component-Centric Framework

While I was on the road last week, I never had a chance to blog about a new article on OnJava: Tapestry: A Component-Centric Framework.

As usual, there are a number of things that rub me the wrong way. For example, I never use the class attribute of the page or component specification, I configure Tapestry to find my pages and my classes in appropriate packages.

The formatting of the examples in the article is a bit odd. I'm not sure who this article serves ... the article claims to show "how simple it is to develop a web application in Tapestry" but it doesn't come close. Actually, if I didn't know Tapestry not only would I not be interested in pursuing it because of this article, I would almost certainly be persuaded not to research further.

Nice to see more Tapestry in print, but as they say, if you want something done right ...

You'll be much better of reading Warner Onstine's Tapestry 101 once that's available. I've been doing the technical edits of this book as each chapter is ready and it's much closer to the mark!

eZing Builder -- WYSIWYG Builder for Tapestry

It's very unfortunate that Spindle has stalled, short of adding Tapestry 4 support. Fortunately, it's a big world and others have started stepping in to fill the gaps. On approach is Cognition, which uses a visual builder tied to a data model driven architecture.

Another one just brought to my attention is eZing Builder. From what I can tell (the site's a little short on documentation, and SourceForge is currently down for maintenance), it's a general purpose WYSIWYG editor for web applications, with specific Tapestry extensions. Built on Eclipse 3.2, and open source. Looks nice.