Wednesday May 28, 2008 I received emails asking for BTrace BOF (JavaOne-2008) slides. Better late than never... I've uploaded PDF of the slides. The BOF was mostly around demos -- slides do not contain much. But, slides have few pointers that may be useful.
Friday May 09, 2008
Here are the few highlights from the talks that I attended today:
TS-5428 Java Technology Meets the Real World: Intelligence Everywhere.
This talk is about pervasive computing (a.k.a ubiquitous computing) with products from Sentilla. There was an interesting demo about humidity sensor detecting changes and sending a message to a host. The "motes" run CLDC 1.1 VM (+ proprietary profile for motes). These motes have ports for sensors and actuators and some built-in sensor. There were many interesting suggestions for embedded programming for such small devices (don't allocate in inner loops and there by leading to to GC kick-in, avoid too many static fields, avoid threads whenever possible and so on).
TS-7575 Using Java Technology-Based Class Loaders to design and implementing a Java platform, Micro Edition
The basic idea is to run JavaME applications (developed for different configurations/profiles/subsets of optional packages) on top of JavaSE. The extended JavaSE classes and packages not available in specific profile or optional package set [implemented by a specific phone] should not be made available to JavaME apps targeted. i.e., only the classes available to a specific phone model should be available. If the JavaME app tries to access any other class, it should receive ClassNotFoundException. The speakers explained how to achieve such "containers" by class loader based isolation. The problem is that they seem to solve only the class access. What about extended methods and fields? For example, platform core classes on JavaSE have superset of methods [more methods on the same class available on JavaME - eg. java.util.Hashtable has more methods on JavaSE). The application classes have to bytecode analyzed and instrumented to take care of field/method accces. It seems that their current product that does not address this yet.
PAN-5542 Developing Semantic Web Applications on the Java Platform.
The discussion started with some nice demos. There was a demo with AllegroGraph RDF store, Twine, a demo with using GRDDL and getting RDF triples by a proxy server. i.e., a proxy serves does the GRDDL transformations to get RDF triples from sites [which could be stored/analyzed with RDF stores subsequently] and a demo with FOAF files. Interesting take aways from the discussion include:
Thursday May 08, 2008
Today Bill, Chihiro, Jaya and I talked on Blu-ray. The talk was centered around the open source project @ http://hdcookbook.dev.java.net - a library and a set of tools to build Blu-ray discs. If you haven't checked out code/docs, you may want to checkout and play with the code. All you need is a laptop with blu-ray drive and a BD-RE disc. Optionally, for added fun you may want to have a hardware bluray player such as PS3 -- so that you can see the output on your TV rather than on a laptop. Other than the session, we also had a very informal BOF on blu-ray, OCAP etc. during the evening. It is good to meet experts in respective technologies in one place!
Other than the the blu-ray stuff, I did attend other talks/BOF. Just after Blu-ray session, I attended "TS-6000 Improving Application Performance with Monitoring and Profiling Tools" talk. This talk was about OS specific tools, JDK tools and third-party tools for profiling and monitoring. Gregg Sporar and Jaroslav Bachorik (NetBeans Profiler team) presented very well. There were many interesting questions/discussions as well. If you haven't done so already, you may want to download VisualVM. If you want bit more fun doing monitoring/profiling, you may want to check out the sources from http://visualvm.dev.java.net and build it yourself. You can build BTrace VisualVM plugin using the command:
c:\visualvm\plugins>ant build
assuming you have checked out VisualVM sources under "c:\visualvm". If you have already checked out BTrace sources under some other directory, say "c:\btrace", you can use
c:\visualvm\plugins>ant -Dbtrace.home=c:\btrace build
To run VisualVM with all the plugins that you built, you can use the following command:
c:\visualvm\plugins>ant -Dbtrace.home=c:\btrace run
Please let us know what features you'd like to see with BTrace and/or BTrace VisualVM plugin.
I attended and liked the "Class Loader Rearchitected (BOF-6180)" BOF. If you have ever written class loaders, chances are that you have faced mysterious deadlocks or ClassCastException that said "ClassCastException: Foo cannot be cast to Foo" or having to decide between overriding loadClass and findclass, you probably should have attended this talk and gave your opinions/suggestions/ideas 
If I understood properly, I think there was a suggestion to add class loader info. to the ClassCastException (something like class-loader-class-name@identity-HashCode style string?) so that one can quickly see it is a class loader issue. Also, there were many questions on loading classes from jar files. Looks like there will be changes to class loader API and class loading in VM for JDK 7.
Wednesday May 07, 2008 In today's sessions that I attended I liked the following:
JRuby: Why, What, How... Do It Now
This talk is a good introduction to (J)Ruby the language and important applications of (J)Ruby. And many pointers to related (J)Ruby sessions. Nice summary!
JavaScript programming language: The Language Everybody Loves to Hate
great talk by Roberto Chinnici. Nice summary of functional and prototype-based object orientation aspects of JavaScript. You can easily impress your friends will some neat snippets of JavaScript You may want to continue the fun by reading Doug Crockford's pages, if you have not do already!
At 7.30 PM, we (I and Kannan) talked about BTrace. There were many interesting questions/discussions -- both during and after the BOF! Today (Wed May 7) will be a Blu-ray day -- it starts with TS-5449 Java Technology for Blu-ray and TV: Creating your own Blu-ray Java Discs session. It is about the open source project @ http://hdcookbook.dev.java.net. Meet you all there!