Thursday March 29, 2007

eBay Internals

javablogs.com -> ostas.blogspot.com -> addsimplicity.com :

It's a presentation on the internal architecture of eBay. Some statistics : 212,000,000 registered users, 2 Petabytes of data, 26 Billion SQL executions, and over 1 billion page views (!!) per day.

Under the section "Scaling the Application Tier - Massively Scaling J2EE", they have a "Step 1 - Throw out most of J2EE. eBay scales on servlets and a rewritten connection pool". That's interesting :)

(2007-03-29 10:50:09 SGT) [Java] Permalink Comments [3]

Tuesday March 27, 2007

IBM J9 JDK in Eclipse

Instructions for setting up the Windows edition of the IBM J9 JDK for local development of mobile applications in Eclipse.

1. Install the IBM J9 JDK for Windows (aka WEME - "Websphere Everyplace Micro Environment").

2. Look for, and unzip weme-win-x86-ppro11_6.1.1.20061110-161633.zip into an empty directory. I chose c:\weme-6.1.1 - just change the references below if you choose a different directory.

3. From Eclipse, go to Windows, Preferences, Java, Installed JREs and click Add.

4. Browse to the directory that was unzipped to earlier (c:\weme-6.1.1).

5. You will get an error message : "Target is not a JDK Root. Java executable was not found"

6. To fix that, copy c:\weme-6.1.1\bin\j9.exe to java.exe in the same directory

7. If you try Step #3 again, you will get another error message : "Target is not a JDK Root. System library was not found."

8. Not a problem : just create the directory c:\weme-6.1.1\jre\lib and copy
c:\weme-6.1.1\lib\jclFoundation11\classes.zip to c:\weme-6.1.1\jre\lib\rt.jar

9. There should be no further complaints from Eclipse at this point.

10. Enter a name for the JRE, let's say, weme-6.1.1

11. Uncheck "Use default system libraries", click Add External Jars, and add the required libraries :

12. Select weme-6.1.1 as your default JRE, click OK, and your project will now re-compile under the J9 JDK.

13. If you try running your application, you will get this error message :

JVMJ9VM011W Unable to load jclfoun10_23: The specified module could not be found.
JVMEXEX013E Internal VM error: Failed to create Java VM
JVMEXEX014I Run C:\weme-6.1.1\bin\java.exe -help for usage

14. Go back to Installed JREs and edit your weme-6.1.1 JRE

15. Under Default VM Arguments, add -jcl:ppro11

16. Your application should now run under the J9 JDK. You should be able to debug as well.

17. (optional) - If you would like to browse the JDK source code, add the source attachment settings :

- Skip the error messages above and enter all the required settings directly to save time. Just showing them here for my own reference.

(2007-03-27 18:19:48 SGT) [Java] Permalink

Monday November 13, 2006

Sun makes Java tech. open-source project

news.yahoo.com :

Computer server and software maker Sun Microsystems said that it had begun to make its Java technology an open-source software project available for free on the Internet. The announcement represents one of the largest additions of computer code to the open-source community - and it marks a major shift for a company that had once fiercely protected the source code used in 3.8 billion cell phones, supercomputers, medical devices and other gadgets.

Making Java an open-source project allows programmers from around the world to examine, modify, fix bugs and contribute new features in Java's underlying code. It requires that any changes be made public. All the Java source code is expected to be released by March 2007. The move covers all Java technology, which includes software that runs on handheld devices, personal computers and servers. Analysts said the decision would likely extend the life of Java, which was released more than a decade ago, and boost business for the company.

See also :

1. Q&A with Tim Bray

(2006-11-13 13:41:40 SGT) [Java] Permalink

Friday December 02, 2005

JDK 1.5.0_06 released

Get the "latest and greatest" Sun Java J2SE 5.0 JDK 1.5.0_06 here.

(2005-12-02 09:18:45 SGT) [Java] Permalink

Thursday October 20, 2005

Dynamic bean sorting

Biow was asking for a way to dynamically sort an ArrayList of bean objects. The beans are your typical JavaBeans with private attributes and getter/setter methods for each attribute. The JDK Collections.sort() method provides for a custom Comparator that you can implement yourself, but it gets tedious very quickly to have to write a bunch of Comparators to sort each field and also having to take into account ascending/descending order.

I had something in mind about using reflection to dynamically invoke the getter method, and then getting the values, and putting that to work in a custom Comparator, but of course someone must have encountered the same problem before. York Davis has written an article on Dynamic Sorting With Java with source code for a DynamicComparator which does exactly what is needed. It accepts Collection, which is even better, which means you can throw in not only ArrayList, but also Vector and so on.

(2005-10-20 11:09:28 SGT) [Java] Permalink Comments [2]

Thursday September 08, 2005

WebLogic Domain/Cluster runtime information

mttech.com, samspublishing.com :

Needed a "proper" way to get the ListenAddress and ListenPort settings that were defined in the WebLogic server's config.xml file (besides opening and parsing the darn file directly, of course, lol). The links above include code for a servlet called InfoCluster which can be adapted to do just that.

This stemmed from a requirement to get the "localhost" address for a multi-homed server. If you just do an InetAddress.getLocalHost(), it appears that, for a multi-homed machine (one with more than one local IP address, due to multiple network cards or virtual adaptors), you will get just one of the available IP addresses, and the order of obtaining that address is implementation-specific to the JDK you're using (!)

On the other hand, obtaining the "ListenAddress" this way now makes the code WebLogic-specific (you know - gain some, lose some). Another way might be to use your system's configuration mechanism (whatever it is) and just do a config.getString() (for example - whatever the API is). And *then* your configuration mechanism will have to take care of deployment onto different machines - which, hopefully, at this point, it is not *your* problem :)

(2005-09-08 13:11:00 SGT) [Java] Permalink Comments [2]

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