JNI Refreshment

Today one of my colleague asked me some questions on JNI implementation. The knowledge seems fading away from me. To avoid it happens again, I recorded the basic steps:

1. Delare your native methods in a normal Java class, for example, HelloJNI.java.
2. javac the java file(HelloJNI.java).
3. javah -jni HelloJNI to generate the .h file(s).
4. Write your native code, using the .h file generated in step 3; copy the function prototye from the .h file into your .c file.
5. compile by using Visual Studio 2005 command shell(cl command).
6. Modify your java class to load the library; recompile it; ready to run it!!!

Reference:

1. http://java.sun.com/docs/books/jni/html/jniTOC.html
2. http://patriot.net/~tvalesky/jninative.html
3. http://java.sun.com/developer/onlineTraining/Programming/JDCBook/jniexamp.html#comp
4. command to compile your c file: c:\test\jnitest>cl /I"C:\Program Files (x86)\Java\jdk1.6.0_24\include" /I"C:\Program Files (x86)\Java\jdk1.6.0_24\include\win32" -LD HelloJNI.c -Felibnative.dll
5. JNI in package
   
   

Decoding IBM DB2 error message

Ever get an IBM DB2 error message like "SQL0407N Assignment of a NULL value to a NOT NULL column TBSPACEID=n1, TABLEID=n2, COLNO=n3 is not allowed. What actually does "TBSPACEID=n1, TABLEID=n2, COLNO=n3" mean? Don't ask me, you should ask IBM DB2, but how?

SELECT C.TABSCHEMA, C.TABNAME,
C.COLNAME
FROM SYSCAT.TABLES AS T,
SYSCAT.COLUMNS AS C
WHERE T.TBSPACEID = n1
AND T.TABLEID = n2
AND C.COLNO = n3
AND C.TABSCHEMA = T.TABSCHEMA
AND C.TABNAME = T.TABNAME

Install Oracle Developer Suite 10g on Windows 7 (64bit)

Recently, I got a task to install Oracle Developer Suite on Windows 7(64bit), but there seems lots of hassles to achieve this goal. There is a thread on Oracle forum on that topic. Here I log what I did to get it installed on my Windows 7(64bit) with 8G RAM.

• extract the setup files (version 101202) downloaded from otn.
• right click the install\setup.exe property, set compatibility to Windows XP SP2
• edit the virtual memory size to custom size from 1024m to 8000m, restart it
• run the install\setup.exe

Hope this helps.

Oracle 11g alert log location

Oracle alert log contains much useful information about your Oracle database, but do you know where is it located and how could you find it out?

1. Connect to the database with SQL*Plus or another query tool, such as SQL Developer.

2. Query the V$DIAG_INFO view as shown in "Viewing ADR Locations with the V$DIAG_INFO View".

3. To view the text-only alert log, without the XML tags, complete these steps:

   1. In the V$DIAG_INFO query results, note the path that corresponds to the Diag Trace entry, and change directory to that path.

   2. Open file alert_SID.log with a text editor.

4. To view the XML-formatted alert log, complete these steps:

   1. In the V$DIAG_INFO query results, note the path that corresponds to the Diag Alert entry, and change directory to that path.

   2. Open the file log.xml with a text editor.

How to use Android Market on Android Emulator 2.2

After some digging, finally I got android market working on Android emulator 2.2 running on Windows Vista. Here is the steps,:

• Start SDK Setup.exe and create an AVD - android-2.2
• Copy system.img coming with the SDK platform to the newly created AVD.

cd c:\Users\dliu\.android\avd\android-2.2.avd
copy c:\labs\android-sdk-windows\platforms\android-8\images\system.img .

• Start the emulator by using command line:

c:\labs\android-sdk-windows\tools>emulator -avd android-2.2 -partition-size 96

• Pull build.prop from the emulator for editing:

c:\labs\android-sdk-windows\tools>adb.exe pull /system/build.prop .

• Comment out ro.config.nocheckin=yes line from the build.prop file just pulled out from the emulator.
• Push back the updated build.prop file to the emuloator

C:\labs\android-sdk-windows\tools>adb.exe remount
C:\labs\android-sdk-windows\tools>adb.exe push build.prop /system/build.prop

• Grab the MoDaCo Custom ROM for Nexus
• Push GoogleServicesFramework.apk, Vending.apk to emulotor, and remove SdkSetup.apk
  

C:\labs\android-sdk-windows\tools>adb.exe push c:\labs\r21-update-nexusone-modacocustomcustomrom-withadditions-chinese-signed\system\app\GoogleServicesFramework.apk /system/app
C:\labs\android-sdk-windows\tools>adb.exe push c:\labs\r21-update-nexusone-modacocustomcustomrom-withadditions-chinese-signed\system\app\Vending.apk /
system/app
C:\labs\android-sdk-windows\tools>adb shell rm /system/app/SdkSetup.apk

• Stop the emulator and delete the files: userdata-qemu.img, userdata.img, cache.img
  
• start the emulator by using command line again, you should get the Android Market in your emulator.
  

SAP IDES 4.7

The best place to start learning SAP is to try out the SAP IDES, International Demonstration and Education System. Here are some of the default settings for IDES 4.7 after installation:

• Client ID: 800

• Login user/pwd: sap*/06071992

• Login user/pwd: ddic/19920706

How to remote debug Tomcat server code?

Either you are a developer of Tomcat or you would like to see how the Tomcat works in a live mode, you may want to set a few break points in the Tomcat codes and to see the code in the live run. How could you set up remote debug for tomcat? Thanks for the JPDA(Java Platform Debug Architecutre) we can easily achieve this goal.

• Start tomcat server with remote debug enabled with JVM parameters: -Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=y and make sure you setting suspend=y to let the tomcat server suspend and wait for debugger to attach to it.
• Start your debugger, I am using Intellij Remote Debug, and here is the settings: Host: localhost Port: 8000
  

That is all. Happy debugging.