Hoang Tran's blog

Turn back to Bochs

2011-06-09T04:07:00.000-07:00

After a few days tried to use QEMU as an emulator for studying low-level software, it turned out to me that QEMU doesn't support much for debugging. Things like step-by-step run, set break points,... is unable. Then I went back to have a try with Bochs. It's amazing that Bochs is not that hard as I've ever thought. It even provides very good debugging features.

Here're some of my notes on Bochs installation and use:

1. Download Bochs source code at http://bochs.sourceforge.net/getcurrent.html

2. Extract Bochs code
$ gunzip -c bochs-version.tar.gz | tar -xvf -

3. Configure to use debugger
$ ./configure --enable-debugger --enable-disasm

4. Install

    $ make

$ sudo make install

5. There an example Bochs configs file name .bochsrc at extracted dir

6. Using Bochs debugger
http://bochs.sourceforge.net/doc/docbook/user/internal-debugger.html

Intel vs AT&T syntax

2011-05-29T03:42:00.000-07:00

There're two popular assembly syntaxes: Intel and AT&T. Intel syntax is popular in Windows world. In Linux, AT&T syntax is more popular though GAS (Gnu Assembler) supports both.

The following lists some major differences of the two syntaxes:

AT&T prefixes register with % sign
* Intel:
eax, ebx, ecx,...
* AT&T:
prefix by % sign: %eax, %ebx, %ecx,...
AT&T prefixes immediate value with $ sign, Intel is not
* Intel: 10, 80h
* AT&T: $10, $0x80
AT&T and Intel syntax use opposite instruction operands
* Intel:      mnemonic destination, source
   Ex: mov eax, 100
* AT&T: mnemonic source, destination
   Ex: movl $100, %eax
AT&T suffixes instruction to specify instruction's operand size (1 byte: b, 2 bytes: w, 4 bytes: l) but Intel uses directive before operands (1 byte: byte ptr, 2 bytes: word ptr, 4 bytes: dword ptr)
* Intel:
mov al, byte ptr foo
* AT&T:
movb foo, %al

Assembly Language

2011-05-28T03:08:00.000-07:00

Assembly can be seen as machine language but in symbols/mnemonics instead of 0s or 1s. So one can make use of any aspect of computer's power if writing programs in assembly.

Assembly is specific to machine architecture. IA32 (also called x86, i386) is the most popular architecture for PC.

Register
Can be classified in 4 types:
- general purpose (eax, ebx, ecx, edx)
- pointer/index (esp, ebp, esi, edi)
- instruction pointer (eip)
- flags (eflags)

These are all 32 bits. Each register contains 8-bit and 16-bit parts. Ex: eax (32 bits), ax (16 bits), ah (8 bits), al (8bits).
Instruction
- arithmetic/logic: add, sub, and, or,...
- control: jmp,..
- data movement: mov,..
Operand
- register: operand value is contained in register
- immediate: operand value is a constant
- memory: operand value is in memory
Addressing mode
Addressing mode is the way to specify a memory address.
- absolute:
  address = a value
- register:
  address = register content
- displacement:
  address = register content + a value
- indexed:
  address = register content + a value + another register content (index) * another value (scale)
Subroutine
- subroutine is a set of instructions
- parameters passed to subroutine are usually pushed on stack

Some notes on QEMU

2011-05-17T08:48:00.000-07:00

I am finding a computer emulator so that I can use to experiment some low-level softwares. There are two prominent free and open-source emulators: Bochs and QEMU. Bochs seems more popular but lacks of documentation. So I have decided to use QEMU because it's quite simple to use and well documented.

1. Installation (on Ubuntu)
   $ sudo apt-get install qemu

2. Start emulator
   $ qemu [options] [disk_image]
   --> This means start an emulator with specified options and disk_image (usually contains OS)

   Ex:
   $ qemu linux.img
   --> Start an emulator with default options and its hard disk contains linux.img

   There are lots of options which specify how your emulated computer could be such as what type of its cpu, hard disk, video card, sound card,... You can get more details on each option in QEMU documentation.

3. Monitoring
   QEMU provides a way to monitoring your emulator in which you can inspect your emulator, control it, change its devices, query its status,...

   You can switch back and forth between the emulator and its monitor with keystrokes: Ctrl+Alt+2 and Ctrl+Alt+1

   Some monitoring commands:
   (qemu) help or ? [cmd]
   (qemu) change device setting
   (qemu) x/fmt addr
   Virtual memory dump starting at addr
    (qemu) xp/fmt addr
   Physical memory dump starting at addr
   ...

Use helpers in controller

2011-05-16T07:48:00.000-07:00

Rails applied Restful as part of its design.

To follow Restful, you should:

1. Model your web app as resources
2. Manipulate your app's resources through a conventional interface

Ex:
- if you have Product resource then urls to CRUD (Create, Edit, Update, Delete) this resource would be:

Action	Urls	Web Method	Restful Interface
Create	/products	POST	products_url
Edit	/products/1/edit	POST	edit_product_url
Update	/products	PUT	product_url
Delete	/products	DELETE	product_url

Then to get links to delete/edit a product through Restful interface, we can use link_to method as below:

link_to 'Edit', edit_product_path(product)

link_to 'Remove', product_path(product), :confirm => 'Are you sure?', 
        :method => :delete

By default, you can only use above interfaces in View layer. How can we use those in Controller layer?

In Rails 2, call through @template variable
@template.link_to('Edit', edit_product_path(product))

In Rails 3, call through view_context method
view_context.link_to('Delete', product_path(product), :confirm => 'Are you sure?', :method => :delete)

References

[1] http://stackoverflow.com/questions/3300582/rails-3-template-variable-inside-controllers-is-nil

[2] http://railscasts.com/episodes/132-helpers-outside-views

Code folding in Emacs

2011-04-12T01:25:00.000-07:00

Code folding is a feature to wrap or unwrap a block of code. It can help you to see an overview of your code. This is a quick and simple way to have that feature in Emacs. I modified it a little bit to make it more flexible as the way I want.

;; code folding

(defun toggle-selective-display (level)
  (interactive "nEnter indentation level: ")
  (set-selective-display level)
  )

(global-set-key "\M-3" 'toggle-selective-display)

So, if I have this code:

class User < ActiveRecord
  has_many :projects
  has_many :assignments

  def full_name
    "#{first_name} #{last_name}"
  end

  def show_project_names
    projects.each do |prj|
      puts prj.name
    end
  end
  
end

then when I press Alt+3 4, all code that was indented at level 4 (4 spaces) will be wrapped as below:

class User < ActiveRecord
  has_many :projects
  has_many :assignments

  def full_name...
  end

  def show_project_names...
  end
  
end

if I press Alt+3 2, all code indented at level 2 will be wrapped:

class User < ActiveRecord...

end

if I press Alt+3 0, wrapped code will be unwrapped again.

class User < ActiveRecord
  has_many :projects
  has_many :assignments

  def full_name
    "#{first_name} #{last_name}"
  end

  def show_project_names
    projects.each do |prj|
      puts prj.name
    end
  end
  
end

It's quite fun, right?

A simple URL shortening algorithm

2011-03-20T02:38:00.000-07:00

Shortening a URL is a convenient way to save long URL to make use of space when posting. It's especially popular on Twitter where message is limited to 140 words. Many websites provide this service such as tinyurl.com, bit.ly,...

There some gems or wrapper to use that service in your Rails app. But the shortened URLs belong to another domain (ex: http://bit.ly/ek8Hhe which belongs to bit.ly). If you want to make it belonged to your domain (ex: http://example.com/wfds7i), you must implement your own URLs shortener.

This is a simple way to do that.

Basically, the problem is:

given a URL, how to map it to a string which has pattern XXXXXX, where X belongs to {0..9a-zA-Z}. There would be 62^6 = 56800235584 such strings. That amount is almost enough.

Then the simple idea to solve that problem is:

map the URL to an integer in 1..62^6. That number must correspond to a string in space {XXXXXX} that could be calculated by using a 10-base to 62-base conversion algorithm (you can understand easily by figuring out how to convert a decimal number to hexa number).

Here is an implementation of mine in Ruby:

class URLShortener
  CHARSET = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
  BASE = 62
  CODE_LENGTH = 6

  def self.encode(id)
    code = ""
    while (id > 0) do
      code = CHARSET[id % BASE].chr + code
      id = id / BASE
    end

    (code.length > CODE_LENGTH) ? "" : "0" * (CODE_LENGTH - code.length) + code 
  end

  def self.decode(code)
    return -1 if code.length != CODE_LENGTH
    id = 0
    for i in 0..(CODE_LENGTH-1) do
      n = CHARSET.index(code[i])
      return -1 if n.nil?
      id += n * (BASE ** (CODE_LENGTH - i - 1))
    end
    return id
  end
end

Making ajax form

2011-03-20T00:13:00.000-07:00

Making an ajax form is a javascript code snippet that we see very frequently. So I've tried to write it as a pattern that could be easy to reuse when needed.

<form action="do_something" method="post" id="do_something_form"> 
  Field 1: <input type="text" name="field1" id="field1" /> 
  <br /> 
  Field 2: <input type="text" name="field2" id="field2"/> 
  <br /> 
  <input type="submit" value="Submit" /> 
</form> 

<script>
  jQuery('#do_something_form').submit(function(event){
    // stop normal form submitting
    event.preventDefault();
  
    // get form's fields
    var field1_val = jQuery('#field1').val(),
        field2_val = jQuery('#field2').val(),
        url        = jQuery(this).attr('action');

    // send request
    jQuery.post(url,                   // ajax url
                {
                  field1: field1_val,
                  field2: field2_val
                },                     // data passed to server side
                function(response){    // callback 
                  // do things with response data, ex:
                  alert(response["message"]);
                  if (response["success"] == true) {
                    // ... 
                  }
                },
                "json"                 // response's format 
    );
  });
</script>

Then at backend:

def create
  @form = params
  
  if some_condition
    @result = {
      :success    => true,
      :message    => "Resource has been created successfully!",
      :other_data => {}
    }
  else
    @result = {
      :success => false,
      :message => "Creation failed! Please try again!"
    }
  end

  render :text => @result.to_json
end

Reference:
http://api.jquery.com/jQuery.post/

Tổng quan về kinh tế học #1

2011-03-13T00:40:00.000-08:00

Nói đến kinh tế là nói đến quá trình sản xuất, trao đổi hàng hóa, của cải vật chất và tinh thần trong xã hội. Thông qua quá trình đó, con người tương tác với nhau để tạo ra của cải vật chất hay những giá trị mới, tái phân bổ chúng, phục vụ cho các nhu cầu trong cuộc sống, rồi lại lao động và lại tái tạo ra những giá trị mới khác,... Đó là tổng thể của cái gọi là nền kinh tế. Làm sao để nền kinh tế tạo ra thật nhiều giá trị? Làm sao để quá trình sản xuất và lưu thông hàng hóa hiệu quả hơn?... Đó là những vấn đề của kinh tế học.

Một trong những yếu tố cơ bản của nền kinh tế là thị trường và tiền tệ.

Nơi hàng hóa được đem ra trao đổi, mua bán được gọi là thị trường. Vd: thị trường bất động sản, thị trường chứng khoán, chợ,...

Hàng hóa có thể được trao đổi, mua bán trên thị trường dưới nhiều hình thức:
- Trao đổi trực tiếp:
   vd: 1 trâu đổi 100 thúng lúa
- Trao đổi gián tiếp (quy đổi sang một loại hàng hóa trung gian)
   vd: 1 trâu <-> 100 thúng lúa
   1 bò <-> 80 thúng lúa
   1 căn nhà <-> 1000 thúng lúa
   hoặc,
   1 trâu <-> 1 lượng vàng
   1 bò <-> 0.5 lượng vàng
   1 nhà <-> 100 lượng vàng

Yếu tố đóng vai trò trung gian trong trao đổi hàng hóa được gọi là tiền tệ. Thời xưa, tiền tệ cũng chính là hàng hóa (lúa, vàng, bạc,...), bản thân chúng có giá trị nội tại. Khi kinh tế ngày càng phát triển, nhiều hình thức tiền tệ khác ra đời làm cho quá trình trao đổi, lưu thông hàng hóa thuận tiện, nhanh chóng hơn như tiền đồng, tiền giấy, tiền điện tử,... Tiền tệ trở về với đúng bản chất của nó: làm trung gian trong trao đổi hàng hóa, bản thân nó không có hoặc có rất ít giá trị nội tại. Vai trò trung gian, đại diện cho giá trị thực đó của tiền tệ được đảm bảo bởi nhà nước và pháp luật.

Be careful writing hooks to Rack layer (middle ware layer) in Rails

2011-03-12T09:38:00.000-08:00

I've got this error from a Rails project:

ERROR NoMethodError: private method `split' called for 0:Fixnum

Following the link below gave me some clues:
http://rack.lighthouseapp.com/projects/22435/tickets/52-read-error-nomethoderror-private-method-split-called-for-0fixnum

1. something's wrong in Rack layer

2. someone wrote incorrect code that hooked to Rack layer

Case #1: rarely happened

Case #2: may be

I did some search and found this code in authentication module:

response.headers["Expires"] = 0

This must be the cause of the error.

Though the correct code is just:

response.headers["Expires"] = "0"

it still took me over a day to find out and fix that bug!!!

Simple but not simple!

A case of "Broken Pipe" error in Rails

2011-03-12T07:06:00.000-08:00

Have you ever seen "Broken PIPE" error in Rails?

It somehow like this:

*** Exception Errno::EPIPE in Passenger RequestHandler (Broken pipe) (process 22235):
    from /usr/lib/ruby/gems/1.8/gems/passenger-2.1.2/lib/phusion_passenger/rack/request_handler.rb:67:in `write'

This error seems appear when your program interacts improperly with external programs. In my case, it happened to me in a project that I used XMLRPC library to remotely communicate with some web services.

My implementation for that feature is as following:
- create a XMLRPC connection object
- use that XMLRPC object every time calling a webservice API

There some other guys had been headache with that error also:
http://gaveen.owain.org/2008/04/errnoepipe-broken-pipe-mysql-error-in.html
http://stackoverflow.com/questions/1082166/exception-errnoepipe-in-passenger-requesthandler-broken-pipe
http://stackoverflow.com/questions/4351624/ruby-on-rails-errnoepipe-broken-pipe

and the reasons they found come around Passenger or Mysql.

In my case, I've got the same thing even with upgrading Passenger or migrating to another web server.
After a lot of retries, I've found that if I call the API very often, "Broken pipe" doesn't appear, but if I stop doing anything for a while and then call the API, it does happen. That observation led me to a guess: XMLRPC connection object may be broken after a certain amount of time (timeout). Excellently, that's exactly right! I then changed my implementation so that every time calling a webservice API, I use a newly created XMLRPC connection object instead of using the same XMLRPC connection object for every API calls.

That solved my problem!

Django Overview

2011-02-22T09:08:00.000-08:00

(will add more soon...)

#1 Setup a basic Django project

2011-02-19T07:11:00.000-08:00

, I've been getting more and more interested in Django. I think why shouldn't I write a series about it. So, let's start with the basics first: how to setup Django development environment and build a basic Django project.

1. Setup environments

Install Python

   Get Python at http://www.python.org
   To verify if it's already installed, at console:
   $ python
   Python 2.6.6 (r266:84292, Sep 15 2010, 15:52:39)
   [GCC 4.4.5] on linux2
   Type "help", "copyright", "credits" or "license" for more information.

Install Django

   Download a Django release at http://www.djangoproject.com/download/
   $ tar xzvf Django.tar.gz
   $ cd Django
   $ sudo python setup.py install

   To verfiy what's your current Django's version
   $ python
   >>> import django
   >>> django.get_version()

2. Create a basic Django project

To initialize project

   $ django-admin.py startproject mysite
   This will create a basic Django project in mysite directory that looks as below
   mysite/
   __init__.py
   manage.py
   settings.py
   urls.py

Now run a development webserver to see if your Django site works

   $ python manage.py runserver
   Validating models...
   0 errors found.

   Django version 1.0, using settings 'mysite.settings'
   Development server is running at http://127.0.0.1:8000/
   Quit the server with CONTROL-C.

Goto http://127.0.0.1:8000 on your Web browser, you'll see a "Welcome to Django" page. It's works!

So, you have setup a very basic Django project. If you want to make more complex stuffs, you may need to use a database backend, create some models, build your site's templates, mapping urls to what will process & response the corressponding templates (Django call this "views"), add some caching mechanisms to boost performance,...

How caching works in Django

2011-02-18T07:42:00.000-08:00

Last time, I had a chance joining to a Django project. Django is a web framework written by Python. Though I've invested sometime before to study Django and been amazing with it, I haven't really done anything on Django yet. So that's a good opportunity for me to increase my Django knowledge. One of my tasks at start was to study caching supports in Django. Compare to what I knew with Ruby on Rails, I found that caching in Django is very strong and especially well-organized. So, it would be useful to put some summarizations down here.

General rule

given a URL, try finding that page in the cache
if the page is in the cache:
   return the cached page
else:
   generate the page
   save the generated page in the cache (for next time)
   return the generated page
More specific

Advantages and disadvantages of caching backends

	Advantages	Disadvantages
Memcached	- the fastest, most efficient type of cache available to Django - all cached data is stored directly in memory, so there’s no overhead of database or filesystem usage - cached data can be shared over multiple machines, so it’s excellent for scaling - being used by Facebook, Wikipedia,...	- cached data is stored in memory, so it will be lost if server crashes (but it’s not critical because cached data is just temporary) - need to have memcached daemon along the way
In-database cached	- cached data is persistent - could use multiple databases for caching	- setup & manage multiple caching databases would be tough
Filesystem cached	- cached data is persistent - simple to setup	- may not scale well
Local-memory cached	- simple - not nescessary to have runing an external cache server as memcached	- no cross-process caching means it’s not particularly memory-efficient - probably not a good choice for production, just nice for development

Reference
http://docs.djangoproject.com/en/1.2/topics/cache/

Quảng cáo trên Google

2010-10-25T03:15:00.000-07:00

Google cung cấp dịch vụ quảng cáo thông qua bộ máy tìm kiếm.

Có 2 nguồn thông tin mà bộ máy tìm kiếm của Google sẽ tìm khi người dùng gõ một từ khóa:

- thông tin của Google (do Google tự tạo ra)

- thông tin có sẵn trên internet (do người khác tạo ra, như các trang web...)

Kết quả tìm kiếm cũng dc hiển thị theo 2 dạng dựa vào 2 nguồn thông tin trên.

Do đó, chiến lược quảng cáo trên Google cũng gồm 2 hướng:

1. Thuê Google trực tiếp đăng quảng cáo của bạn. Google sẽ đưa thông tin của bạn vào nguồn "thông tin của Google", cái này gọi là dịch vụ Google AdWords, muốn xài cái này cần phải trả tiền, trả càng nhiều tiền thì thông tin của bạn càng dc quảng bá nhiều (tần xuất xuất hiện trên kết quả tìm kiếm trong ngày, vị trí xuất hiện,...). Cái này đòi hỏi người dùng phải có khả năng thanh toán online (Paypal, VISA card, ...) để trả tiền đăng quảng cáo cho Google.

Có 2 khoản cần thanh toán cho Google:

- Chi phí quảng cáo hằng ngày (trung bình khoảng 10$ mỗi ngày)

- Chi phí trả cho mỗi lần có ai đó click chuột vào quảng cáo (0.001$ ???)

Tham khảo:

http://www.youtube.com/watch?v=tx2L6EGa9DY&feature=related

2. Điều chỉnh thông tin của bạn (trang web) để Google dễ dàng tìm thấy (Google càng dễ tìm thấy thì trang web xuất hiện càng sớm trong kết quả tìm kiếm). Hướng này gọi là SEO (Search Engine Optimization). Hướng này đòi hỏi những điều chỉnh về mặt kĩ thuật đối với trang web của bạn sao cho thân thiện với bộ máy tìm kiếm như tối ưu hóa mã nguồn trang web, tạo nhiều liên kết từ bên ngoài tới trang web của bạn...

Ruby code snippets

2010-09-27T02:22:00.000-07:00

1. using 'any?' to check if something in a array/hash

# a = User.all
a.any? {|user| user.name == "Hoang"}

Some ways to refactoring Rails' code

2010-09-23T23:55:00.000-07:00

On the following, I list some ways I found to refactoring my Rails' code. This list would be added more as time's going.

1. Method delegation
   Assume you have two models:
   + User(id, name)
   + Account(id, number, user_id)
   It could be described in Rails as:

   class User < ActiveRecord::Base
   has_many :accounts
   end
   class Account < ActiveRecord::Base
   belongs_to :user
   end

Then if I have an Account instance named account, I could get it's user's name by: account.user.name or I can define an instance method in Account as follow:

class Account < ActiveRecord::Base

belongs_to :user

def user_name

user.name

end

Then you can get account's user name by: account.user_name. We can make the above code shorter by using delegation:

class Account < ActiveRecord::Base

belongs_to :user

delegate :name, :to => :user, :prefix => true ## this will generate user_name methods

end

2. Use define_method to dynamically generate similar methods
Given a model User(id, name, role) where role could be "admin", "moderator", "senior", "junior",... You can write instance methods to see whether a user is "admin", "moderator", ... as follow:

Before
class User < ActiveRecord::Base
  ROLES = {
   :admin => "admin",
   :moderator => "moderator",
   :senior => "senior",
   :junior => "junior"}

   def admin?
   role == ROLES[:admin]
   end

   def moderator?

role == ROLES[:moderator]

end

def senior?

role == ROLES[:senior]

end

def junior?

role == ROLES[:junior]

end

After
class User < ActiveRecord::Base
ROLES = {

:admin => "admin",

:moderator => "moderator",

:senior => "senior",

:junior => "junior"}

ROLES.each_pair do |key, val|

define_method(key.to_s + "?") { role == val}

end

Ruby's origins - a find

2010-05-28T03:01:00.000-07:00

Ruby is a pure Object-Oriented programming language. Everything in Ruby is objects, even classes. Amazing? Let's see why:

irb> 'hello'.class
=> String
irb> String.class
=> Class
irb> Array.class
=> Class
irb> Class.class
=> Class

See even further:

irb> Class.superclass
=> Module
irb> Module.superclass
=> Object
irb> Object.superclass
=> nil

irb> Module.class
=> Class
irb> Object.class
=> Class

So all classes are objects of class "Class". String, Array,.. are instances of class "Class".
Module and Object are super classes of "Class" but also instances of "Class"!!!

Install adva-cms on Windows

2010-05-25T04:36:00.000-07:00

Adva-cms is an open source CMS (Content Management System) platform based on Ruby on Rails. Installing adva on Windows could be a bit tough. Follow is the steps I've tried to get passed:

1. Make sure you already installed ImageMagick and some gems adva requires

2. Just follow adva's installation guide:

# Create your app
rails my-app
cd my-app
rm public/index.html

# Prepare the config/environment.rb and remove the public/index.html
# in config/environment.rb make sure you have:
require File.join(File.dirname(__FILE__), 'boot')
require File.join(File.dirname(__FILE__), '../vendor/adva/engines/adva_cms/boot') # this line

# You *must* use Rails' old routing recognition/generation mode in order for adva-cms to work correctly:
# in config/initializers/new_rails_defaults.rb set:
ActionController::Routing.generate_best_match = true

# Clone the adva-cms ( this might take a bit, grab a coffee meanwhile :) )
git clone git://github.com/svenfuchs/adva_cms.git vendor/adva # or use: git submodule add ...

# Install the core engines and copy the assets
rake adva:install:core -R vendor/adva/engines/adva_cms/lib/tasks # install adva-cms to vendor/plugins/
rake adva:assets:install # symlinks plugin assets to public/

...and get this error

$ rake adva:install:core -R vendor/adva/engines/adva_cms/lib/tasks
(in d:/Document/Projects/AdvaCMS/adva3)
installing engines: adva_activity, adva_blog, adva_cms, adva_comments, adva_rbac, adva_user
rake aborted!
unknown file type: ../adva/engines/adva_activity

(See full trace by running task with --trace)

Let's trace to see why it failed:

$ rake adva:install:core -R vendor/adva/engines/adva_cms/lib/tasks --trace
(in d:/Document/Projects/AdvaCMS/adva3)
** Invoke adva:install:core (first_time)
** Execute adva:install:core
** Invoke adva:install (first_time)
** Execute adva:install
installing engines: adva_activity, adva_blog, adva_cms, adva_comments, adva_rbac, adva_user
rake aborted!
unknown file type: ../adva/engines/adva_activity
c:/Ruby/lib/ruby/1.8/fileutils.rb:1256:in `copy'
c:/Ruby/lib/ruby/1.8/fileutils.rb:451:in `copy_entry'
c:/Ruby/lib/ruby/1.8/fileutils.rb:1325:in `traverse'
c:/Ruby/lib/ruby/1.8/fileutils.rb:448:in `copy_entry'
c:/Ruby/lib/ruby/1.8/fileutils.rb:423:in `cp_r'
c:/Ruby/lib/ruby/1.8/fileutils.rb:1396:in `fu_each_src_dest'
c:/Ruby/lib/ruby/1.8/fileutils.rb:1405:in `fu_each_src_dest0'
c:/Ruby/lib/ruby/1.8/fileutils.rb:1403:in `each'
c:/Ruby/lib/ruby/1.8/fileutils.rb:1403:in `fu_each_src_dest0'
c:/Ruby/lib/ruby/1.8/fileutils.rb:1394:in `fu_each_src_dest'
c:/Ruby/lib/ruby/1.8/fileutils.rb:422:in `cp_r'
d:/Document/Projects/AdvaCMS/adva3/vendor/adva/engines/adva_cms/lib/tasks/adva_cms.rake:139:in install'
d:/Document/Projects/AdvaCMS/adva3/vendor/adva/engines/adva_cms/lib/tasks/adva_cms.rake:126:in `send'
d:/Document/Projects/AdvaCMS/adva3/vendor/adva/engines/adva_cms/lib/tasks/adva_cms.rake:126:in `perform'
d:/Document/Projects/AdvaCMS/adva3/vendor/adva/engines/adva_cms/lib/tasks/adva_cms.rake:119:in `each'
d:/Document/Projects/AdvaCMS/adva3/vendor/adva/engines/adva_cms/lib/tasks/adva_cms.rake:119:in `perform'
d:/Document/Projects/AdvaCMS/adva3/vendor/adva/engines/adva_cms/lib/tasks/adva_cms.rake:35

...so there're something wrong in adva_cms.rake file. It took me a while to understand how this file does things and found the lines that caused bugs:

def source(type, subdir = nil)
"../adva/#{type}" + (subdir ? "/#{subdir}" : '')
end

...so maybe this relative path causes confusing. Let's make it full:

def source(type, subdir = nil)
"#{Rails.root}/vendor/adva/#{type}" + (subdir ? "/#{subdir}" : '')
end

now the engines installed ok, but there's still errors in installing plugins. It caused by paperclip initialization code that uses 'which' command to find path to 'convert' which is a tool provided by paperclip gem but 'which' command does not exist on Windows

d:/Document/Projects/AdvaCMS/adva3/vendor/plugins/adva_cms/config/initializers/p
aperclip.rb:1

Paperclip.options[:command_path] = %x[which convert].chomp.gsub(/convert/, '')

...so just go to ../vendor/adva/engines/adva_cms/config/initializers/paperclip.rb and remove 'which'

Paperclip.options[:command_path] = %x[convert].chomp.gsub(/convert/, '')

then adva's core installation gets passed!

$ rake adva:install:core -R vendor/adva/engines/adva_cms/lib/tasks
(in d:/Document/Projects/AdvaCMS/adva3)
installing engines: adva_activity, adva_blog, adva_cms, adva_comments, adva_rbac
, adva_user
installing plugins: adva_cells
copied 33 migrations to db/migrate
copied 33 migrations to db/migrate/app
copied 33 migrations to db/migrate
== CreateActivitiesTable: migrating ==========================================
-- create_table(:activities, {:force=>true})
-> 0.0050s
== CreateActivitiesTable: migrated (0.0060s) =================================
...

3. Next, install adva's assets and run it up

$ rake adva:assets:install -R vendor/adva/engines/adva_cms/lib/tasks
$ script/server

...and this is what I've got

An issue with Rspec on Windows

2010-05-17T03:51:00.000-07:00

Rspec is a very popular test framework used to test Rails application. I have tried to install and use it for my Rails projects on Windows. It raised a bug when I ran tests:

c:/Ruby/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:440:in load_missing_constant': uninitialized constant RbReadline::Encoding (NameError)

from c:/Ruby/lib/ruby/site_ruby/1.8/rbreadline.rb:4404

I traced back and found these causing lines:

   if defined? ''.getbyte
   @encoding = "X" # ruby 1.9.x or greater
   @encoding_name = Encoding.default_external.to_s
   end

It seems the Rspec uses Ruby Readline library for its command-line interface. It defined getbyte that uses Encoding module which hasn't been defined in this Ruby package on Windows. I then commented out the line using Encoding module and the bug get fixed...

   if defined? ''.getbyte
   @encoding = "X" # ruby 1.9.x or greater
   # @encoding_name = Encoding.default_external.to_s
   end

It's not common to pass over the issue by this way but hopefully it still works fine in my case.

Hello Ruby & Rails

2010-04-26T18:27:00.000-07:00

Ruby is a programming language and Rails (Ruby on Rails) is a web development framework written by Ruby. Those are attracting a lot of fans. Common philosophy that both Ruby and Rails based on is the simplicity, light-weight and beautifulness. You can find how easy it is to programming Ruby like talking. Also, bearing in mind with DRY (Don't Repeat Yourself) or CoC (Convention over Configuration) principles, Rails has made web developing simple and with least efforts.

Keeping track changes and sharing what I've learned from Ruby and Rails are the most important things I target to from this beginning.

So, let's say "hello Ruby & Rails"!

A quick setup for development environment of Rails on Windows

2009-02-08T22:17:00.000-08:00

1. Install Ruby
Use One Click Installer for Ruby

2. Update Gem
> gem update --system

3. Install Rails
> gem install rails

4. Install Sqlite3 & Sqlite3 driver for Rails
- download sqlite and extract to get 3 files: sqlite3.exe, sqlite3.dll, sqlite3.def
- copy 3 above files to ruby/bin
- $ gem install sqlite3-ruby
-> If errors, try another version of sqlite driver, ex:
$ gem install --version 1.2.3 sqlite3-ruby

hello world

2008-07-08T01:29:00.000-07:00

Hi everybody!!!