Millstone

Recently I was playing with Millstone, an open-source "web user interface component library." It makes you feel like you're writing a Swing-style UI, in Java source, and it creates the web interface for you. The nice thing is that if you happen to like the default "theme" (look-and-feel, presentation details), you never to have to get your hands dirty with the HTML or Javascript details. I find the optional Eclipse plugin highly useful, as it features an automatic end-to-end refresh -- you edit the source, and suddenly, it has recompiled everything and refreshed a browser with the new UI (displayed within Eclipse).

Of course, many applications will require some kind of customized theme, which can be done by tweaking, or overhauling, the XSL stylesheets. I have not played sufficiently with XSL to just go in and do this, especially compared to the kind of sweeping changes I like to envision, but it's nice to know that the smart Millstone engineers have achieved such a clean separation that I can do this without modifying my application's Java source code.

One area I want to play with more was validation. Millstone has a nice model for this, with a Validator and Validatable and ErrorMessage classes. Validators can be composed and a bunch of them can be added to a Property or a component, and the ErrorMessage is something that can be stuck onto a component so it shows a little error icon where you click for more info. Of course that's the default behavior and can be customized. It seems like a pretty flexible interface. However, in my brief time I had difficulty getting my Validators to be invoked. According to the Millstone forums, the validation used to be completely automatic, and now you must invoke it explicitly. This doesn't seem surprising, as I'm guessing the automatic stuff didn't completely suit everyone, and enough users needed explicit control. But I had difficulty getting this going. My goal was to use a text field where the user would enter a port number, so I decreed that the text field is only valid when it has a number from 0 to 65535, or simply blank (where a default is inferred). At first I tried adding a change listener which would invoke the validator, but it didn't seem to be invoked after I typed an invalid value ("-1" or "abc") and hit "return". It's quite possible my page needs some kind of submit button, I don't know. When I set setInvalidAllowed(false) on my TextField, the validator did seem to run, and I would get the expected red error icon if I entered an invalid value. One interesting thing the system did on these errors is to reset the text field to blank. I find that intiguing, because I'm not generally used to a UI control changing its value on its own. Presumably you can override or nullify this behavior somehow, because I could envision the text field holding some long text string with a single typo, and the user looking on with dismay to see it disappear forever. Maybe the text field has an undo history, I don't know.

Despite this experience, I'm impressed with the Millstone package and would like to see it come more into the mainstream, because it looks like a well-designed package with plenty of room to grow.

Welcome, gentle reader. JFKBits is about software and life; hopefully how to make life better, or less painful, through software. I would like to publish several things here:

1. What's new (or old) in technology -- what's out there, what I'm finding useful, what could be better. I don't necessarily stay very up to date, so don't be surprised if I write about something that's 10 years old, if I just started experiencing it.
   
2. Stories -- "war stories" and "bug stories" about my own software experience, and generate discussion on what we can learn from these
3. Tips and tricks that I find for debugging specific problems. An ideal for me on this front is that whenever I encounter an error message or a funny bit of behavior, I blog it along with any solution I find. I feel this would be helpful in terms of replicating useful information, as well as adding to the reference count of any useful web sources.
4. Theory Stories -- My own attempts to explain, for myself mostly, some concept or technology. In particular I would like to finish a project I started in my master's thesis where I was attempting to explain what I had learned, in a manner that was less formal than is required by a thesis.
5. Reflections on technology and how it fits into the rest of life. I intend most of my audience to be tech-focused, and I think we tend to assume technology *is* life, or at least an important element of Life As it Was Intended To Be, but we should probably force ourselves to admit, occassionally, that technology serves some higher purposes. If we have to do that, might as well use bits.
   

Those are the goals. I'm looking forward to this.

--JFK