Using vnstat in CentOS to Monitor and Log Network Traffic

1. install rpmforge repository

2. yum install vnstat

3. vnstat --testkernel

4. reference: Monitoring bandwidth usage with vnStat under CentOS 5 Linux

Javascript and PHP AES encrypt decrypt library

This is a Javascript AES encrypt decrypt library
AES Advanced Encryption Standard

And this is a PHP AES encrypt decrypt library
AES in PHP

Symfony theme for NetBeans

A nice guy make a symfony color theme for NetBeans. You can download from his googlecode page: Symfony Color Scheme for NetBeans v1.3

解決 DejaVu Sans Mono 字型在 NetBeans 下中文顯示成方塊的問題

1. 找到 NetBeans 安裝路徑, ex: C:\Program Files\NetBeans 7.0.1
   進入 etc 資料夾 ex: C:\Program Files\NetBeans 7.0.1\etc
   打開 netbeans.conf 並搜尋 netbeans_jdkhome 參數
   該參數存放的是 JRE 的路徑 ex:"C:\Program Files\Java\jre6"
2. 進入 JER 的路徑, 並進到 lib 資料夾 ex: C:\Program Files\Java\jre6\lib
3. 複製一份 fontconfig.properties.src 並更改檔名成 fontconfig.properties
4. 編輯 fontconfig.properties 檔
   

   新增下列的內容
   filename.DejaVu_Sans_Mono=DejaVuSansMono.ttf
   filename.DejaVu_Sans_Mono_Bold=DejaVuSansMono-Bold.ttf
   filename.DejaVu_Sans_Mono_Bold_Oblique=DejaVuSansMono-BoldOblique.ttf
   filename.DejaVu_Sans_Mono_Oblique=DejaVuSansMono-Oblique.ttf
   
   修改下列的內容
   sansserif.plain.alphabetic=DejaVu Sans
   sansserif.bold.alphabetic=DejaVu Sans Bold
   sansserif.italic.alphabetic=DejaVu Sans Oblique
   sansserif.bolditalic.alphabetic=DejaVu Sans Bold Oblique
   monospaced.plain.alphabetic=DejaVu Sans Mono
   monospaced.bold.alphabetic=DejaVu Sans Mono Bold
   monospaced.italic.alphabetic=DejaVu Sans Mono Oblique
   monospaced.bolditalic.alphabetic=DejaVu Sans Mono Bold Oblique
   sequence.sansserif.x-windows-950=
     alphabetic,chinese-ms950,dingbats,symbol,chinese-ms950-extb
   sequence.monospaced.x-windows-950=
     alphabetic,chinese-ms950,dingbats,symbol,chinese-ms950-extb
       

5. 做完上述的修改後, 再進入 NetBeans -> Tools -> Options -> Fonts & Colors -> Syntax -> Default -> Font, 選擇 Monospaced 字型, 這樣就可以正確地顯示 DejaVu Mono 的字型了, 收工!

Usful link for Symfony2

Symfony2 Base Path and Root Path

StofDoctrineExtensionsBundle

Symfony2: Checking Coding Standards

Creating your own services for the Symfony2 DIC
Symfony2 and Dependency Injection
Symfony2: Moving Away From the Base Controller

Sage - Online Mathematical Software

Sage is an mathematical software, the coolest point is it can run with any web browser.

I tried a sample plot function below, the usability is awesome too!

x=var('x')
plot(-0.3+(x+0.6)^0.5, (0,100))

Benchmarks for mt_rand() and rand()

Benchmarks results as below:

mt_rand() 10000000 times for 4.7026278972626 seconds
each one average is 0.00000047 seconds
rand() 10000000 times for 4.7438910007477 seconds
each one average is 0.00000047 seconds

The test machine is Amazon EC2 High-CPU Instances (20 ECU)

Another test as below:

mt_rand() 10000000 times for 2.4974269866943 seconds
each one average is 0.00000025 seconds
rand() 10000000 times for 2.4646849632263 seconds
each one average is 0.00000025 seconds

The test machine is Amazon EC2 Micro Instances (1 ECU)