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Scratch

Posted by daniel on August 12, 2004 at 9:47 AM PDT

Capture signatures on a touchscreen-enabled J2ME device

Some java.net featured articles cover important technology and some are just cool. Scott Davis' article on Scratch. Scratch lets you use a Palm or other J2ME device to capture signatures in the field. He takes you through what Scratch does out of the box and then shows you how to customize it. Scratch consists of three screens: ScratchList, ScratchForm, and ScratchCanvas. The model is the Scratch object, ScratchController is, of course, the controller, and ScratchDao is used to store and retrieve Scratch objects from the filesystem.


In today's Weblogs, Chet Haase asks "Ever wondered what kind of image to use in your application? Or which of the several methods of creating images you should use to create it? This article tries to make this pretty huge topic just a tad clearer..." he suggests ToolkitBufferedVolatileManagedImage Strategies.

Alex Toussaint looks at the SOA promise to Deploy Once Deliver Anywhere. He writes that "The core of the idea is pretty straightforward - take all your software and make them available as services on the network. Making this happen is the challenge."

Satya Komatineni takes A journey through IT. He writes "Recently where I work I had a request to create a web page that displays some data from a database. Well I figured I could do that. This reminded me of Leonardo Da Vinci writing to a prospective employer that he could architect war machines while only on the last line of that long letter that he would mention that he could paint as well if an occasion arises."


In
Also in Java Today
, Jack Shirazi and Kirk Pepperdine's most recent Eye on Performance article Determining the riskiness of change is really about code coupling. When you compile a class, how many other classes need to be compiled. Afferent coupling measures "how many classes depend on me" while efferent coupling measures "how many classes do I depend on". These metrics help you determine how much a change may ripple through and effect your system - they are mainly interested in the implications to bug introduction during late performance tuning. Most often, loosely coupled code is the answer, but they do provide examples of where bad coupling is desirable.

Anil Sharma presents his thoughts on the EJB 3.0 spec in the JavaWorld article EJB 3.0 in a nutshell. He praises much of the work of the committee and details the changes in EJB 3.0 in a concise and useful summary. He ends the article with concerns that include worries about the number of annotations already being used and a hope that "the model won't turn out to be as complex and excessively SQL-bound as it seems at this stage."


You can continue to share your thoughts on EJB 3.0 in today's
Forums. The moderators respond to reader comments about the new EJB, "We hear what you're saying. If EJB 3.0 gives us simplicity without breaking good design principles, we would have nothing against it. Unfortunately, a lot of ugliness and potentially problematic behaviour is built into the model, and we need to get them addressed. We're reviewing our model as well, strengthening our story on DTOs and testability, and identifying the potential for further simplification without sacrificing good design principles."

Jimothy writes that you should not always leave your optimization til the end. "As programmers gain experience, we learn things that are almost always ineffecient, and learn to avoid writing things in those ways to begin with. [..] A second problem is that [w]hen optimization is saved for late in the project, the code that was carefully tested is not the code that is about to be deployed."

Should you always Refer to objects by their interfaces? JWenting writes of "cases where I had a single class (I thought) but then an extra requirement creeps in causing for a slightly different execution flow which is best handled by just taking a slightly different implementation of that same class. Voila, you now have 2 classes already. Another option here would be abstract base classes, which serve a similar purpose."


In Projects and Communities, Daniel Brookshier, a
JELC
community leader posts a list of new projects in that community along with descriptions that range from a digital library to a graphical tool to simulate IP datagram routing.

The javaserverfaces project in the Java Enterprise community
is the official standard implementation of JSR 127. Download a recent slide presentation, User Docs, Developer Docs, and the latest weekly build.


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