Friday, December 24, 2010

Favorite Tech Links

We used to come across different links while we working on a particular work. Each link will give an idea. Some will serve our purpose and some will not. I just want to group all those links which helped a lot along with what type of purpose it served. Hence i start writing this post and i hope it will be helpful to the people who used to google it.
Cloud Computing
Scaling an Internet architecture - This link clearly tells the difference between horizontal and vertical scaling in cloud.
SAAS, PAAS, IAAS - Difference - This link clearly tells the difference between SAAS, PAAS & IAAS and also guidance for Cloud Computing.
Introduction to Multi-Tenant Architecture - This link gives a basic idea about how multi-tenant architecture is built with an example.
Cloud computing terms - In order to get a knowledge on cloud computing, we should know the terminologies used over there. This link listed down most of the terminologies used in cloud.

Dynamic Web Pages with JSON

Nivo Slider – The most awesome jQuery Image slider

JSF & RichFaces
Practical example of the JSF 2.0 event system
Using datatables in JSF
Rich Faces - Live Demo - Scrollable DataTable
Switching tab via javascript in RichFaces

Thursday, December 23, 2010

97 Things Every Programmer Should Know

1. Act with Prudence

2. Apply Functional Programming Principles

3. Ask, “What Would the User Do?” (You Are Not the User)

4. Automate Your Coding Standard

5. Beauty Is in Simplicity

6. Before You Refactor

7. Beware the Share

8. The Boy Scout Rule

9. Check Your Code First Before Looking to Blame Others

10. Choose Your Tools with Care

11. Code in the Language of the Domain

12. Code Is Design

13. Code Layout Matters

14. Code Reviews

15. Coding with Reason

16. A Comment on Comments

17. Comment Only What the Code Cannot Say

18. Continuous Learning

19. Convenience Is Not an -ility

20. Deploy Early and Often

21. Distinguish Business Exceptions from Technical

22. Do Lots of Deliberate Practice

23. Domain-Specific Languages

24. Don’t Be Afraid to Break Things

25. Don’t Be Cute with Your Test Data

26. Don’t Ignore That Error!

27. Don’t Just Learn the Language, Understand Its Culture

28. Don’t Nail Your Program into the Upright Position

29. Don’t Rely on “Magic Happens Here”

30. Don’t Repeat Yourself

31. Don’t Touch That Code!

32. Encapsulate Behavior, Not Just State

33. Floating-Point Numbers Aren’t Real

34. Fulfill Your Ambitions with Open Source

35. The Golden Rule of API Design

36. The Guru Myth

37. Hard Work Does Not Pay Off

38. How to Use a Bug Tracker

39. Improve Code by Removing It

40. Install Me

41. Interprocess Communication Affects Application Response Time

42. Keep the Build Clean

43. Know How to Use Command-Line Tools

44. Know Well More Than Two Programming Languages

45. Know Your IDE

46. Know Your Limits

47. Know Your Next Commit

48. Large, Interconnected Data Belongs to a Database

49. Learn Foreign Languages

50. Learn to Estimate

51. Learn to Say, “Hello, World”

52. Let Your Project Speak for Itself

53. The Linker Is Not a Magical Program

54. The Longevity of Interim Solutions

55. Make Interfaces Easy to Use Correctly and Hard to Use Incorrectly

56. Make the Invisible More Visible

57. Message Passing Leads to Better Scalability in Parallel Systems

58. A Message to the Future

59. Missing Opportunities for Polymorphism

60. News of the Weird: Testers Are Your Friends

61. One Binary

62. Only the Code Tells the Truth

63. Own (and Refactor) the Build

64. Pair Program and Feel the Flow

65. Prefer Domain-Specific Types to Primitive Types

66. Prevent Errors

67. The Professional Programmer

68. Put Everything Under Version Control

69. Put the Mouse Down and Step Away from the Keyboard

70. Read Code

71. Read the Humanities

72. Reinvent the Wheel Often

73. Resist the Temptation of the Singleton Pattern

74. The Road to Performance Is Littered with Dirty Code Bombs

75. Simplicity Comes from Reduction

76. The Single Responsibility Principle

77. Start from Yes

78. Step Back and Automate, Automate, Automate

79. Take Advantage of Code Analysis Tools

80. Test for Required Behavior, Not Incidental Behavior

81. Test Precisely and Concretely

82. Test While You Sleep (and over Weekends)

83. Testing Is the Engineering Rigor of Software Development

84. Thinking in States

85. Two Heads Are Often Better Than One

86. Two Wrongs Can Make a Right (and Are Difficult to Fix)

87. Ubuntu Coding for Your Friends

88. The Unix Tools Are Your Friends

89. Use the Right Algorithm and Data Structure

90. Verbose Logging Will Disturb Your Sleep

91. WET Dilutes Performance Bottlenecks

92. When Programmers and Testers Collaborate

93. Write Code As If You Had to Support It for the Rest of Your Life

94. Write Small Functions Using Examples

95. Write Tests for People

96. You Gotta Care About the Code

97. Your Customers Do Not Mean What They Say

Wednesday, September 1, 2010

Password protection to website directory - .htaccess

A simple technique to protect the website folder from access is as given below.

Step 1:

Create a simple file with an extension .htaccess

Step 2:

Create a simple file with an extension .htpasswd

Step 3:

Copy the given below commands in the .htaccess file and save it.

AuthName "folder name"
AuthType Basic
AuthUserFile /full/path/to/.htpasswd
Require valid-user

- the folder name is the website folder you need to do password protect
- /full/path/to is the full path of the .htpasswd file

Step 4:

Give the username and password as like below in the .htpasswd file and save it.


- username is the normal user name that you can give for protection
- password is the encrypted form of your password that you can give for protection
(You can get the encrypted code from the KXS website )

Step 5:

Place the .htaccess file in the folder where you need to protect.

Step 6:

Place the .htpasswd wherever you want inside the ftp but you need to specify the full path of the file in the .htaccess file. The full path may vary based on the hosting provider. An easy way is there to find the full path. Download the following php file Path Info. Place the file where you want to know the full path. Access the php file from the server. It will give you the full path.

Thats it! Now if you try to access the files inside the folder, it will ask for the username and password and your work is done.

For more information, you can visit this, HtAccess Tutorial site

Friday, August 6, 2010

Deploy Rails on Heroku

Heroku is one of the popular web based ruby hosting platform to launch our rails application. We can host our ROR demo applications free of cost to a certain level. Features like repository support, database support,etc are available. Using this we can host our application, work on that application from anywhere and update the application at anytime.
The following things are required in order to deploy the ROR application on Heroku.
1Heroku Account Setup
2GitHub Account Setup
3Repository Setup - Git Installation
4Public(ssh) key generation
5Repository Authentication
6Heroku Installation
7ROR Application setup
8Launch Application in Heroku
Heroku Account Setup

An account is needed in order to work with Heroku.create an account from the Heroku site. Your username and password credentials are required in order to deploy the application. You can also create an application inside the heroku account for checking purpose.

GitHub Account Setup

GitHub account is required in order to authenticate the public keys in repository.Create a free account in the Git Hub site
After you logged in to the account, you need to upload the SSH public keys generated in the Public(ssh) key generation.

Repository Setup - Git Installation
In order to work with heroku, git repository is required.Download the latest Git version and install it.
Public(ssh) key generation
A public SSH key is required in order to authenticate the remote servers.
There are different ways to create SSH public key.
If your Git repository installation is already done, you can create as like below.
Type the following in command prompt
set path=%path%;C:\Program Files\Git\bin; [setting the git path]
cd C:\Program Files\Git\bin [Move to the bin folder]
ssh-keygen -t rsa -C "emailid" [generating a key pair with your email id] and id_rsa files will be created. Use these two files wherever, ssh authentication is required.Copy the key from and paste it in the public key of github account.
For more information, refer Generating SSH keys
Repository Authentication

In order to test your git remote repository, you need to copy the SSH key files( and id_rsa) and paste it in .ssh folder in [C:\Program Files\Git\.ssh].

Type the following in the commmand prompt
if Successfully authenticated message comes, then your remote repository setup will be working fine.
Heroku Installation
In order to deploy rails on heroku, Heroku gem needs to be installed in your system.
Type the following in the commmand prompt
set path=%path%;c:\ruby\bin; [set the ruby path]
gem install heroku [Remote installation of heroku gem]
heroku list[To list down the deployed applications]
It will ask to enter your heroku user crendentials.If, No public ssh key found error will be displayed, it means that, ssh authentication key is required. For that, you need to copy the SSH key files( and id_rsa) and paste it in .ssh folder in C:\Documents and Settings\[user]\.ssh.
Now if you run heroku list command again, successful authetication occurs by entering the user credentials and it will list down the applications that are currrently running in your heroku account.
ROR Application setup

Before starting with heroku, we need to ready with our ROR application. If it is not ready yet, refer the blogs, Setting up Ruby on Rails Environment and Ruby on Rails for Beginners in order to get ready with the application.

Launch Application in Heroku
Now, all the setup is ready and we are ready to launch the application.
As a first step, move to rails application directory in the command prompt and initialise the git repository. Type the following in command prompt
git init [initialise the application directory]
git add . [add the files to the repository]
git commit -m "your comment" [commit the files in the directory]
Now your application is initialized and added to git repository.
As a second step, an application needs to be created on heroku and it has to be added to the remote repository.
heroku create app-name [creating the application on heroku with the specified name]
git remote add heroku [initialise the application to remote repository]
As a third step, push the code to the master repository.
git push heroku master [push the code to master repository on heroku server]
If it is first application to launch in heroku, then create .gems file with the rails version as shown below and put it in root folder to rectify the warning.
rails -v 2.3.8
Once done, run the following command for db creation in heroku
heroku db:migrate [creating db structure in heroku server]
Now the ROR application on heroku is ready and you can access it from anywhere.
1Heroku site
2Git Hub Site
3Ruby On Rails for Beginners
4Setting up Ruby on Rails Environment in Windows
5Hosting your Rails app – first look at Heroku
6Getting Started with Heroku on Windows

Sunday, August 1, 2010

Setting up Ruby on Rails Environment in Windows

Ruby on Rails, often shortened to Rails or RoR, is an open source web application framework for the Ruby programming language. It is intended to be used with an Agile development methodology that is used by web developers for rapid development.
The following things are required in order to set up the ROR environment.
1Ruby Installation
2Testing the Ruby environment
3Rails Installation
4Setting up the server
5Setting up the database
6Testing the ROR environment
Ruby Installation

Rails framework is created using Ruby language and hence setting up the Ruby environment is the first thing to proceed. Download the latest ruby file ruby186-26.exe for windows and install it.
Testing the Ruby environment
Before moving on to rails, we need to test whether our ruby environment is set up properly or not. There are many tutorials available for testing it and you can check this blog Execute RUBY program on Command Prompt which is very simple to check at this stage.
Rails Installation
Once the ruby enviroment is ready, it is the time to install rails.Type the following in command prompt

gem update --system [To update the system with latest gems for ruby]
Ex: C:\ruby\prg>gem update --system
gem install rails --include-dependencies [Installation of rails along with all dependencies]
Ex: C:\ruby\prg>gem install rails --include-dependencies
The above installation is completed by automatically downloading from ruby site.
Setting up the server
Once the application is installed, we need to check whether the server setup is completed.By default, WEBrick server is coming along with rails installation. There is no seperate installation required.
In order to check the server, a sample application is required.
Type the following in command prompt
rails MyRails [creating an application called MyRails]
Ex: c:\rails>rails MyRails
Ex: c:\rails>ruby script/server [start the server & You will get a message console as given below....]
=> Booting WEBrick
=> Rails 2.3.8 application starting on
=> Call with -d to detach
=> Ctrl-C to shutdown server
[2010-07-24 00:12:41] INFO WEBrick 1.3.1
[2010-07-24 00:12:41] INFO ruby 1.8.6 (2007-03-13) [i386-mswin32]
[2010-07-24 00:12:41] INFO WEBrick::HTTPServer#start: pid=14200 port=3000
Now you can launch the application, http://localhost:3000 and a default welcome page will be displayed.
If you have done the above process, then server setup is completed.
Setting up the database
Rails can be easily configured with SqlLite database.We can install the database by remote using the below command.
install -r sqlite3-ruby
Ex: c:\rails>install -r sqlite3-ruby [remote installation of sqlite3 database]
In order to run the database, dll file is required and you can download here sqlit3 DLL Download
Download and extract the file[sqlite3.dll, sqlite3.def] in C:\WINNT\system32 folder.

Now your system is ready for working with database.
There are some firefox Add-Ons available in order to view the SQLite database.
Testing the ROR environment

You can test the above environment by writing sample applications.One of the simple tutorial to get started with is given in the blog, Ruby On Rails for Beginners
Now the ROR environment is ready you can successfully run any type of applications in Rails.
1Rails Forum
2Derek Anderson's blog
3Ruby Forum
4Execute Ruby Program on Command Prompt
5SqLite Downloads
6Ruby on Rails for Beginners

Friday, July 16, 2010

How to post source code/syntax in Blog?

If you want to post the source code or highlight the syntax in Blogger, you can follow the below steps.
1. Login to Blogger and Go to design view
2. Edit HTML
3. Copy the CSS from Syntax Highlight CSS and paste it above the end of css section(i.e before ]]-->) in blogger template.
4.Download the code from Syntax Highlighter Support
and paste the code at the bottom after the comment, end outer-wrapper and above the end of body tag.
5. Save it and you are ready to use the syntax highlighter
Now you can post the code snippets by using “pre” or “textarea” tag as below.
In the pre tag just use, class="language" name="code". Language is the type of code we are going to put. For ex, ruby, java, xml, html etc..

Given below is the sample for ruby code.

def show_with_map
@incident = Incident.find(params[:id])
respond_to do format
render :text=>@incident.to_xml (:only=>[:latitude, :longitude, :title, :description], :root=>"data")


Thanks for the original source from Heisencoder Blog.

Monday, May 17, 2010

Cloud Computing

What is Cloud computing?
It is Internet-based computing, whereby shared resources, software and information are provided to computers and other devices on-demand.

Why do we need that?
Round the clock availability of resources is a must and we can achieve using this.