leongz.tech

Tomcat 's Clustering vs Load Balance

2006-04-06T16:10:00.000+08:00

Clustering involve Session Replication, ensure the session in TomcatA still works when TomcatA was die, and move to the same session to TomcatB for process.

Load Balance, can't work like Clustering, only ensure the load still able to process in TomcatB if TomcatA dies. Divides into JK Native connector, HTTP Server with mod_proxy, balancer webapps.

More details for Clustuering and Load Balance.

PHP in MQ series ..

2006-02-22T11:12:00.000+08:00

Did a google on PHP + MQ.

Here are some useful result.

http://www.tjonahen.nl/mqseries/

http://pecl.php.net/package/mqseries

PHP Still can work with MQ. Just that IBM doesn't provide that.

Y2038 Bug

2006-02-15T08:58:00.000+08:00

Found a Unix Bug that might give Y2K like of effect

Y2038 bugs in Chinese

Apache + Tomcat

2005-11-17T14:34:00.000+08:00

Found some mystery Error on the Apache Error Log

1)[DATE TIME][warn] (OS 64)The specified network name is no longer available. : winnt_accept: Asynchronous AcceptEx failed.

2)[DATE TIME][warn] (OS 121)The semaphore timeout period has expired. : winnt_accept: Asynchronous AcceptEx failed.

3)[DATE TIME] [notice] Parent: Created child process 6420
[DATE TIME] [notice] Child 6420: Child process is running
[DATE TIME] [notice] Child 6420: Acquired the start mutex.
[DATE TIME] [notice] Child 6420: Starting 250 worker threads.

WTF?

Power PS command

2005-09-09T16:41:00.000+08:00

ps -p -o vsz = to print out certain column in PS result

ps lU --forest = to see the user's processes.

Tips to change the Tomcat's Log

2005-09-08T12:29:00.000+08:00

<Logger className="org.apache.catalina.logger.FileLogger"
directory="D:/" prefix="localhost_examples_log." suffix=".txt"
timestamp="true"/>

In order to specify the Log file's location, specify the "directory" clause

Win XP to Mac OS

2005-08-29T10:44:00.000+08:00

Well.. Found a site that can change the Win XP Theme to Mac OS ! without having the OS change ! Cool huh?

Emulation Manual - A complete guide on how to change your Windows XP to Mac OS X
By alang

Mustang the Java SE 6

2005-08-19T18:28:00.000+08:00

Found the j2se 6.

Don't have chances to play around for J2SE 5 Tiger. It comes the Mustang!!

some of SOA

2005-08-18T18:12:00.000+08:00

Service-Oriented Architecture (SOA) and WSDL is under this SOA!

AOP

2005-08-16T11:15:00.000+08:00

Aspect Oriented Programming concern more on crosscuting of issues before implementing a System. What a cool topics!

File in Dos and Linux

2005-08-09T14:56:00.000+08:00

mv file.txt file.bak; tr -d '\r' < file.bak > file.txt

The above command will help to save the day!

myisamchk To Recover DB!

2005-08-03T12:26:00.000+08:00

Source From this : http://builder.com.com/5100-6375-5193721.html

Data corruption is every DBA's worst nightmare. There's nothing quite like the experience of coming to work one morning, finding that four years of hard-earned corporate data has just been corrupted, and the entire organization is looking to you to recover it. It sure beats coffee for a wake-up call.

If your database is MySQL, though, there's still hope. Over the course of this article, I will show you how to use MySQL's built-in crash recovery tools to check your database, and hopefully recover all the data you just lost.

Built-in tools
When it comes to repairing and checking tables, MySQL offers two options:

The MySQL distribution ships with a tool called "myisamchk," designed specifically to check and repair MyISAM tables (the default table type used by MySQL). This tool can scan your databases, identify problems, optimize tables for faster lookup, and optionally repair corrupted tables. The myisamchk tool is invoked from the command line.
In addition to the tool above, MySQL also allows you check and repair tables using SQL commands. The CHECK TABLE, REPAIR TABLE, and OPTIMIZE TABLE commands can be used on a running MySQL server and need to be entered through a MySQL client.

Most of the time, it's preferable to use myisamchk because it is significantly faster than using SQL commands.

Checking tables
If you're having trouble accessing a table, first try checking it for errors. To check a table, shut down the server and type myisamchk at the command prompt, followed by the table's file name, as shown below:
$ myisamchk /usr/local/mysql/data/db2/payroll.myi
Checking MyISAM file: /usr/local/mysql/data/db2/payroll.MYI
Data records: 1153 Deleted blocks: 0
- check file-size
- check key delete-chain
- check record delete-chain
- check index reference
- check data record references index: 1
- check record links

Use the complete path to the table file instead of just the table name. Remember to include the file extension as well.

You can pass myisamchk command line arguments, including those shown in Table A, to control how intensively it checks the table.
Table A

Argument	Description
myisamchk --fast	Perform a quick check, only verifying if the table handler closed successfully
myisamchk --medium-check	Perform a faster check, by calculating a checksum for the indexes in each record and verifying that checksum against the index tree
myisamchk --extend-check	Perform a thorough check of the table, verifying the data in each record

Command line arguments for myisamchk

Repairing tables
If your check reveals errors, or if you see cryptic error messages about table handlers or corrupt indexes, then you need to try repairing the table. Unplug the phone, turn off the Blackberry, and cancel your appointments, because you're going to be busy for a while.

The first—and most important—thing you can do before repairing a corrupted table is to back it up. Never try running a repair operation on a table without backing it up; if you fail, your data might be in worse shape than originally and may even become unsalvageable. Backing up the original table file allows you the option of trying a different technique if your first attempt doesn't work.

Next, shut down the MySQL server. This is because myisamchk makes changes to the table file itself, so you don't want other users accessing or otherwise manipulating the file during the repair operation. Remember, don't just terminate the server with a call to "kill"; instead, use the mysqladmin SHUTDOWN command to ensure that MySQL closes all open tables gracefully and doesn't further compound your problem.

Once the table file is backed up and the server down, you can run myisamchk with the --recover option, as shown below:
$ myisamchk --recover /usr/local/mysql/data/db2/payroll.myi
- recovering (with sort) MyISAM-table '/usr/local/mysql/data/db2/payroll.MYI'Data records: 1153
- Fixing index 1

The --recover option reconstructs the MySQL table index file after weeding the corrupted table of invalid or previously deleted records that could be causing a problem.

In the unlikely event that the --recover option fails, revert to the original table file and try the --safe-recover option. This is slower, because MySQL needs to scan through the records in the data file one by one and them restore the index, but it can sometimes work better than a regular repair operation.
$ myisamchk --safe-recover /usr/local/mysql/data/db2/payroll.myi
- recovering (with keycache) MyISAM-table '/usr/local/mysql/data/db2/payroll.MYI'
Data records: 4

If you still have no luck, it usually means that the table's index and/or description files are corrupt. Typically, the only way around this is to create new, empty files and con MySQL into using the new "good" files instead of the original "bad" ones. This process is quite complex and thoroughly documented in the MySQL manual and mailing lists, so I won't repeat it here—suffice it to say that it's worked like a charm on the few occasions I've had to use it. Most of the time, you won't need to go this far, as the regular --recover option will fix most common corruption problems.

Quick tip: If your MySQL tables get corrupted because of frequent server crashes, it could be because of insufficient disk space available to the server. Try increasing the disk quota limits for the "mysql" user and see if the problem goes away.

Using CHECK TABLE and REPAIR TABLE
As noted previously, you can also run check and repair operations from a MySQL prompt, via the CHECK TABLE and REPAIR TABLE commands. In this case, however, the server must not be taken down. Instead, since these commands can only be sent to the server via a client, the server must be running throughout the process. To avoid other users accessing the table from another client on the network, you can shut down and restart mysqld with the --skip-networking option, which tells MySQL not to accept any TCP/IP connections from the network, so you can work on it alone.

Consider the following example of running a CHECK TABLE command:
mysql> CHECK TABLE articles;
+--------------+-------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------+-------+----------+----------+
| db1.articles | check | status | OK |
+--------------+-------+----------+----------+
1 row in set (0.02 sec)

You can add the FAST, MEDIUM, and EXTENDED keywords to the command to obtain behavior similar to that available in myisamchk. For example:
mysql> CHECK TABLE articles EXTENDED;
+--------------+-------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------+-------+----------+----------+
| db1.articles | check | status | OK |
+--------------+-------+----------+----------+
1 row in set (0.02 sec)

When it comes to repairing tables, too, MySQL offers the REPAIR TABLE option, as below:
mysql> REPAIR TABLE articles;
+--------------+--------+----------+----------+
| Table | Op | Msg_type | Msg_text |
+--------------+--------+----------+----------+
| db1.articles | repair | status | OK |
+--------------+--------+----------+----------+
1 row in set (0.01 sec)

As with the myisamchk tool, the REPAIR TABLE command can take one of two additional options: QUICK, which tries a quick repair, and EXTENDED, which rebuilds the index after reading each record in the table.

An option here is to use the mysqlcheck utility, which provides a command line front end to the CHECK TABLE and REPAIR TABLE commands, allowing you to check and repair tables without first taking the server down. Everything that you can do with CHECK TABLE and REPAIR TABLE can be done with mysqlcheck, by passing appropriate command line options to the program.

Final thoughts
Since MySQL's tools are quite sophisticated and will do most of the work for you, there isn't too much else for you to do when it comes to salvaging data from your tables. Most of the time, the myisamchk tool works very well and will get your data back; for the more extreme cases, the manual suggests some last-ditch options.

What you should take away from this tutorial, though, is one important note: While crash recovery is fine and MySQL's tools are sophisticated enough to get you out of most jams, prevention is always better than a cure. So create a backup schedule for your data, and follow it rigorously. Backing up your data on a daily, weekly, or monthly basis (depending on how often it changes) is the first step to insuring yourself against data loss.

SHOW STATUS in Mysql

2005-08-03T12:01:00.000+08:00

Beyond the basic SHOW STATUS statistics I described earlier, the command also offers more technical data which can be used to assess things like memory usage, cache performance, and resource allocation. Here are some of the important variables in this category.

Open_tables, Opened_tables
This statistic shows you the number of tables currently open, while the Opened_tables variables shows the number of tables opened since the server was last restarted. These values provide a good indication of whether your table cache is of the right size; a high value for Opened_tables indicates that your cache should be larger.

Slow_queries
This statistic indicates the number of queries that have taken longer than a predefined per-query time limit. A large value here indicates that the server is not able to process queries at the speed it should and is a cause for concern (although you should make this determination after checking the slow query log, which contains the actual query strings, to see if it's the queries themselves that are unusually long or complex).

Select_scan
This statistic shows the number of joins which required a full scan of the first table named in the join. Since a full table scan is time- and resource-intensive, a high value here means that your queries are operating inefficiently and perhaps require further optimization.

Select_full_join
This statistic reveals the total number of joins performed without making use of indexes. An index speeds up table searches and is advisable on all fields that are queried frequently. Therefore, a high value here means that MySQL is not using indexes and is therefore taking longer to build a result set. The problem can be corrected (or at least mitigated) by indexing important fields of the join.

Qcache_hits
This statistic shows the number of accesses to the new MySQL query cache. The query cache stores the results of frequently-used queries so as to speed up response time; a high value here means that MySQL is working efficiently by using the cache instead of rebuilding result sets every time the same query is fired.

Save Point n Roll Back!

2005-08-02T15:01:00.000+08:00

BEGIN;
UPDATE accounts SET balance = balance - 100.00
WHERE name = ’Alice’;
SAVEPOINT my_savepoint;
UPDATE accounts SET balance = balance + 100.00
WHERE name = ’Bob’;
-- oops ... forget that and use Wally’s account
ROLLBACK TO my_savepoint;
UPDATE accounts SET balance = balance + 100.00
WHERE name = ’Wally’;
COMMIT;

Postgres SQL

2005-08-01T12:17:00.000+08:00

su - postgres
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
/usr/local/pgsql/bin/postmaster -D /usr/local/pgsql/data >logfile 2>&1 &
/usr/local/pgsql/bin/createdb test
/usr/local/pgsql/bin/psql test

but it works for me in this way.

su - postgres
initdb -D /usr/local/pgsql/data
postmaster -D /usr/local/pgsql/data > /usr/local/pgsql/data/pgsql.log &
createdb test
psql test

PHP + Flash

2005-07-22T17:43:00.000+08:00

PHP + Flash + SMS Tutorial Site

java.sql.SQLException: Communication link failure:

2005-07-18T15:32:00.000+08:00

Wondering what's worng with this?

install Tomcat

2005-07-13T14:26:00.000+08:00

// extract the jakarta-tomcat-xxx.tar.gz to ur path example /var/tomcat
tar -zxvf jakarta-tomcat-xxx.tar.gz /var/tomcat

// write a shell script example tomcat-startup.sh

# tomcat-startup.sh
#!/bin/sh
export JAVA_HOME="YOUR JAVA PATH"
sh /var/tomcat/bin/startup.sh
# end of file

// start the tomcat with the command
sh tomcat-startup.sh

Install JAVA in Linux

2005-07-13T14:23:00.000+08:00

With j2sdk-1_4_2_08-linux-i586.rpm

rpm -ivh j2sdk-1_4_2_08-linux-i586.rpm

rpm -qa j2sdk

updatedb

to Remove:
rpm -e j2sdk

Bash Edit:

export JAVA_HOME=/usr/java/j2sdk1.4.2_02
export J2EE_HOME=/usr/java/j2sdkee1.3.1
export JVMSTAT_HOME=/home/MNC_SW/jvmstat
export MY_SQL=/home/MNC_SW/mm.mysql-2.0.14-bin.jar
export CLASSPATH=.:/$JAVA_HOME/lib/tools.jar:$MY_SQL:$CLASSPATH
export PATH=.:$JAVA_HOME/bin:$J2EE_HOME/bin:$JVMSTAT_HOME/bin:$PATH
export LD_LIBRARY_PATH=.:/home/MNC_SW:$LD_LIBRARY_PATH

PHP Frameworks

2005-07-07T14:41:00.001+08:00

Consist of Cake, Plankton, Mojavi, Seagull

source : timwilling.com's blog

PHP or Java?

2005-07-07T14:41:00.000+08:00

Here some note on that

PHP or Java

Flash Player, Here you come!

2005-07-06T15:55:00.000+08:00

Thanks to Bill. Got the Flash Player 1.1 for Nokia 6600!!

Hacking

2005-07-06T15:54:00.000+08:00

Been busy Hacking Pass few day :D

REPAIR TABLE name

2005-07-01T18:46:00.000+08:00

Stupid got this Problem at Mysql.

[249] ERROR 1030: Got error 127 from storage engine

Got this solve with the following:
http://www.issociate.de/board/post/224834/Got_error_127_from_storage_engine.html

REPAIR TABLE name

Got Another Stupid Solution to solve is is

FLUSH TABLE

It gona refresh all ur Database. something like Stop and Start again!

Save the New Line SMS

2005-07-01T13:31:00.000+08:00

String strMessageSend = URLEncoder.encode(strRSMessage);
strMessageSend = strMessageSend.replaceAll("\\+%5Cn", "%0D%0A");
strRSMessage = strMessageSend;

Made me find out the whole morning.

Same Apps Different Language

2005-07-01T10:46:00.000+08:00

Check this.. trying build 99 Bottles of Beer with 727 Programming Language

99 Bottles of Beer

Idea that might works

2005-06-30T21:19:00.000+08:00

Having some idea, where maybe can provide some platform that able to sell.. with Flash Lite. Should start looking into those things!

wjview

2005-06-30T21:17:00.000+08:00

Hahaa... found this command... but can't work.... no idea

China Linux

2005-06-29T21:41:00.000+08:00

Found a china linux site. seem this on cool

http://www.douzhe.com

http://www.chinaunix.net/

MMS

2005-06-17T19:55:00.000+08:00

How MMS works?

I wish to figure out that!

PHPEclipse

2005-06-16T12:18:00.000+08:00

manage to get that run finally!!! that is cool...
setting the PHP in Eclipse...
test ur PHP with ECLIPSE!!

Open Source n Microsoft

2005-06-14T20:37:00.000+08:00

Which one are you? Open Source? Microsoft? There is a trend where people are moving from Microsoft to Open source... any reasons why? Saving more money? huhh??? i totally disagree..
Expertise/Skills workers might cost u bigger amount....

SAP

2005-06-10T22:59:00.000+08:00

get some ebook for my friend on SAP. so lucky and nice that having chances to explore in SAP... Wish i can = )

SWF 2 SIS for Flash Lite

2005-06-10T16:22:00.000+08:00

Play flash@swf in ur mobile with SIS.!
Check this.

swf2sis

route command in WIN

2005-06-10T15:39:00.000+08:00

ROUTE command - The function and syntax of the Windows ROUTE command is similar to the UNIX or Linux route command. Use the command to manually configure the routes in the routing table. (source)

Bluetooth Sensor

2005-06-10T15:04:00.000+08:00

We can have sensor in our Phone Now!
It use to be my dream to make the similar project. But can't really turn ON due to laziness.!
Anyway say Thanks to Developer behind! What a lovely project.
Check this.

Nokia Bluetooeh Sensor

Tomcat in Eclipse

2005-06-10T11:15:00.000+08:00

Hooraayy..

Make Tomcat run in my Eclipse.
Here some note:

EclipseAndTomcatTutorial

Hello World.

2005-06-10T11:14:00.000+08:00

Decided to post all IT relevant matter here.!