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Divide and Conquer

Posted by tball on April 1, 2008 at 9:07 AM PDT

As anyone following the JavaFX Script compiler project knows, we have a schedule gun to our heads to finish a useful tool quickly, so the interpreter-based prototype shown at last year's JavaOne can be retired. It's a big job since the language doesn't have a specification yet, but our team of four engineers plus some really good volunteers are set to deliver what looks to be a great product. Of course I'm biased in this appraisal since I'm one of its contributors, but feel free to browse the project's source or subscribe to its dev and/or commits email aliases and make your own assessment.

Unfortunately, it has become more obvious as the project progresses that when our clients say "compiler" they really mean a full SDK, similar to what is delivered by the JDK. In particular, our management just assumed that a version of the javadoc tool which understands JavaFX Script would magically appear without any stated requirements or staffing. So we had a sub-project with a short deadline, no engineer available, and frustrated customers.

To make matters worse, javadoc engineers are hard to find since the job requires two unique skill sets: compiler engineering and web designing. Why does the JDK's javadoc output look dated? Because compiler engineers have owned it for the past few years. Why was it lagging behind the language a few years ago? You guessed it, our doc-writers were supporting it.
Now, our team understands compilers, obviously, but none of us have any design skills worth noting. However, we have some engineers with great design skills on other teams. The "correct" solution would be to pull one engineer from each team and have them work together, but there wasn't time nor anyone available. Sound familiar?

What we did was follow the Unix rules for tool development: break the task apart, define a tool for each part, and use ASCII text to communicate between them. I wrote a simple doclet that dumped all information available from the Doclet API to an XML file (other people have done this over the years), then copied the JDK's javadoc source and enhanced it to provide JavaFX Script-specific information for that doclet (the doclet also works with Java sources when used with the JDK's javadoc). Joshua Marinacci then wrote an XSLT translator to generate XHTML pages similar to what javadoc's standard doclet creates. We use this tool to generate the project's UI Runtime documentation, and soon, all JavaFX Script-based API. The full tool source is here.

This divide-and-conquer strategy really pays off. Neither Josh nor I put much time into this project (as shown by how short both the doclet and XSLT script are), so our main jobs weren't impacted much. This approach also makes it much easier for our community to contribute: don't like the (currently primitive) output? An XSLT file is much less intimidating than javadoc's source, so jump in and make it better. But why limit ourselves to one output format? Just use the tool's -xsltfile option to use your own translator. And why limit ourselves to documentation generation? That XML file defines a model of any JavaFX Script and/or Java-based program, which can be used by other tools. As the Unix tool masters learned early on, breaking a big tool up into smaller, specialized tools opens the door to all kinds of unanticipated uses.

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Hi, great job, again! It's up to date, contains API for animation package and I'm sure we will see some great looking documentation soon:) Thanks a lot, Jiri