Posted by editor
on May 21, 2008 at 7:21 AM PDT
Bots for beginners... also:
Featured Podcast: j1-2k8-mtT04: TrackBots, Greenfoot, and the RoboSim Contest: a How-To
Java Today: OpenJDK in Fedora 9, GlassFish LinkedIn group, and wildcards in generics
Weblogs: More on Java enums, NetBeans certification, and nigrating WebLogic's JSP TagHandler example to GlassFish
Forum Posts: WSDL doc tool, getting the same stateful bean through different means, and RMI and garbage collection
Bots for beginners
Having been in attendance for most of this year's Community Corner mini-talks, one thing that impressed me was how the robots on the other side of the booth were accurately simulated in the Greenfoot programming environment, as displayed in several mini-talks. Credit for this goes to the trackbot-greenfoot project , which allows you to try out the very simple trackbot API before downloading it onto a real device.
To get people interested in trying out trackbot programming and setting them loose in the maze, Shawn Silverman gave a daily mini-talk introducing the trackbots, their API, and the Greenfoot environment. The first of these is
today's JavaOne Community Corner Podcast . In
j1-2k8-mtT04: TrackBots, Greenfoot, and the RoboSim Contest: a How-To , Shawn
describes the basics of how to simulate a TrackBot using the Greenfoot environment. By the end of the session, attendees should understand how to use the robot's sensors to interact with the environment.
In Java Today ,
the Red Hat Magazine article Open source project: OpenJDK by Andrew Haley offers a history of the incorporation of OpenJDK into Fedora 9. "At the 2006 JavaOne conference, Sun announced plans to open source Java. This wasnâ€™t exactly a surprise to those of us working on Java at Red Hat, given that there had been rumblings before. But this was a real announcement. We were immediately interested in learning exactly which license Sun would choose. [...] We were thrilled to hear Sun announce in November 2006 that it had selected the exact same license as GNU Classpath."
The Aquarium reports that a LinkedIn "GlassFish" group is now available : "GlassFish now has a LinkedIn group . Thank you to Ryan for setting this up! My understanding is that all GlassFish users are welcome to join, and this includes GlassFish Portal, GlassFish ESB, Sailfin, etc."
One of the most complicated aspects of generics in the Java language is wildcards, and in particular, the treatment and confusing error messages surrounding wildcard capture. In the Java theory and practice article Going wild with generics , veteran Java developer Brian Goetz deciphers some of the weirder-looking error messages emitted by javac and offers some tricks and workarounds that can simplify using generics.
In today's Weblogs , John FergusonÂ Smart offers
A Short Primer on Java Enums - Part 2 .
"In the first part of this article, we looked at the basics of how to use enums in Java 5. In this part, we look at some more advanced use cases, including how to use enums with Hibernate."
NetBeans Platform Certification and training , MasoudÂ Kalali asks,
"do you know that you can get certified in developing software based on NetBeans platform?"
Finally, SekharÂ Vajjhala discusses
Migrating WebLogic's JSP TagHandler example to GlassFish .
"I migrated WebLogic's JSP TagHandler example from WebLogic Samples to GlassFish. This is next in my series of examples describing migration to GlassFish from different application servers. Here is my experience with the migration."
Today's Forums section begins with a
project query from samarth rastogi.
"We are a team of 5 working on the project: "WSDL Doc tool". Project description: To develop a tool that reads WSDL and generate human readable HTML description (like xsddoc and javadoc does for XSD and java, respectively). The goal will be to develop an engine of this tool in a reusable way so that it can be used from CLI, Ant, or integrated into Metro runtime so that it can be used with live endpoints So if anyone has any info abt this project, please inform me."
Miroslav Nachev would like to know
How to take the same Stateful Bean from Remote RMI-IIOP and Local Stateless Bean .
"After few tests I found that when one Stateful Bean is retrieved (doLookup) through RMI-IIOP the instance is the same which must be. The problem is when the same Stateful Bean is retrieved from the server side from Stateless or Stateful bean. My question is there any way from server side to retrieve the same Stateful Bean as from client side (RMI-IIOP)?"
Finally, Russ Petruzzelli is working through concerns with
RMI and garbage collection .
"Documents state that RMI needs to force a GC to ensure remote objects are unexported. Why it is bad that the server doesn't know if a remote client has dropped its reference to the server's exported remote objects? (This is the stated reason for RMI forcing GCs.) Is it that the remote jvm can't clean up its own objects in its JVM if the server is still hanging on to it? It seems the server, if left to its own devices, (ie no forced GCs) will clean up whatever objects are unreferenceable in its own time, whether RMI related or not."
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