dan.thoughts » Ruby

Debugging PHP applications in terminal

Dan Sosedoff — Sat, 03 Jul 2010 05:45:39 +0000

Most of Ruby web frameworks have terminal logging in development environments. It makes application debugging process much easier than using file logging. Especially for AJAX requests. Of course there is simple solution – use Firebug and javascript console. Unfortunately it is not that convenient.

So, one day i came up with idea to make the same ruby-like style of application logging, even with colorized output.
I decided to use EventMachine library as a server platform. And API is based on JSON packets, via json/pure. Simple, isnt it?

And i called it DebugServer. Pretty understandable

Installation

To install just type

$ sudo gem install debugserver

And for information type:

$ debugserver -i

Usage: debugserver [options]
    -h, --host HOSTNAME              Server hostname
    -p, --port PORT                  Server port
    -i, --info                       Get usage information

By default it will start on localhost:9000.

Usage in PHP

First, download library from GitHub repository: http://github.com/sosedoff/debugclient-php

And then:

// place it into app initialization file
$debug = DebugClient::instance();
$debug->connect();
 
// .... and write it to terminal output
$obj = array(
  'id' => rand(0, 0xFFFF),
  'name' => 'Sample name',
  'time' => strftime('%m-%d-%Y', time())
);
 
// these functions are globally defined
debug_clear(); // clear terminal
debug('This is a plain text message.');
debug_info('This is an informational message.');
debug_warning('This is a warning message.');
debug_error('This is an error message.');
debug_dump($obj);
 
// optional
$debug->close();

Results:

Sources

DebugServer: http://github.com/sosedoff/debugserver
PHP Client: http://github.com/sosedoff/debugclient-php

Generate sitemaps with Ruby and XmlSitemap gem

Dan Sosedoff — Fri, 18 Jun 2010 23:10:38 +0000

Made a simple gem for website sitemap generation. Could be used in any Ruby/Rails/Merb/Sinatra application. It does not have any caching in that case if you want to use framework built-in cache methods.

Installation:

$ sudo gem install xml-sitemap

Example

pages = Page.all(:order => [:updated_at.desc] # DM model
map = XmlSitemap::Map.new('somedomain.com') do |m|
  m.add(:url => '/', :period => :daily, :priority => 1.0)
  m.add(:url => '/contractors', :period => :daily, :priority => 1.0)
  pages.each do |p|
    m.add(
      :url => url_for_page(p),
      :updated => p.updated_at,
      :priority => 0.5,
      :period => :never
    )
  end
end
# render the sitemap
puts map.render

Sinatra Example

# ... your code
 
get '/sitemap.xml' do
  map = XmlSitemap::Map.new('domain.com') do |m|
    m.add(:url => '/')
    m.add(:url => '/posts', :period => :weekly)
  end
 
  headers['Content-Type'] = 'text/xml'
  map.render
end
 
# ... more code

Options

:url – page path, relative to domain (ex.: /test), String.
:period – freqchange attribute, Symbol, :none, :never, :always, :hourly, :daily, :weekly, :monthly, :yearly
:priority – priority attribute, Float class,(0.0..1.0)
:updated – (optional) last_update attribute, Time class

Source Code

http://github.com/sosedoff/xml-sitemap

Using Amazon product images on your website

Dan Sosedoff — Tue, 15 Jun 2010 06:20:17 +0000

Amazon has an awesome image service. You can use their product images on your site, adjusting them for you needs. All you have to know – one image url of your product. Having that string will provide you an access to its dynamic image scaling service which i had to use recently.

So, lets say you have books on your website, but you dont have any good images for them. There is 2 ways to solve your problem: 1) download it from whatever place and resize 2) use amazon!

Here goes small overview.

Unfortunately, i didnt have any time to play with image service for different countries, but i assume that wont change that much. Lets take a look on a regular image:

http://ecx.images-amazon.com/images/I/41ygBmdaIfL._SL500_SS100_.jpg

It has different parts:
1) URL base: http://ecx.images-amazon.com/images/I/
2) Image code: 41ygBmdaIfL
3) Size format (surrounded by underscores): _SL500_SS100_
4) Format: jpg/gif/png

Some words about image format. It can vary from square thumbnails to images with specific max width and height. For example: _SX100_ will produce image that 100 pixels wide, height will be calculated proportionally. SH100 will give opposite result, scaled by 100 pixels maximum height, SS100 – 100×100 pixels thumbnail. And so on, you can find other similar crop codes while exploring amazon store on different pages, all you need is to take a look on image sources.

Now, we need to use this with Ruby:

require 'net/http'
 
module Amazon
  # parse amazon image url and get image code and extension
  def self.parse_image(url)
    result = url.scan(/^http:\/\/ecx.images-amazon.com\/images\/I\/([a-z0-9\-\%]{1,})(.*)_.(jpg|jpeg|gif)/i)
    unless result.nil?
      unless result[0].nil?
        match = result.first
        return {:code => match.first.to_s, :extension => match.last.to_s}
      end
    end
  end
 
  # make a new amazon image url based on code and size
  def self.make_image(image, size)
    "http://ecx.images-amazon.com/images/I/#{image[:code]}._#{size.upcase}.#{image[:extension]}"
  end
 
  # check if actual image exists
  def self.check_image(url)
    begin
      uri = URI.parse(url)
      req = Net::HTTP::Get.new(uri.path)
      res = Net::HTTP.start(uri.host, uri.port) { |http| http.request(req) }
      return res.code == '200' && res.content_length.to_i > 0
    rescue Exception
      false
    end
  end
end

And usage:

url = 'http://ecx.images-amazon.com/images/I/51O65dIoZCL._SX117_.jpg'
info = Amazon.parse_image(url)
unless info.nil?
  new_url = Amazon.make_image(info, 'sx100')
  if Amazon.check_image(new_url)
    puts "Cool! Resized image: #{new_url}"
  else
    puts "Sorry, this image does not exist!"
  end
else
  puts "Cant identify image!"
end

Some notes about the process. The only reason why method “check_image” uses GET method instead of HEAD is because if image cannot be generated or not found in amazon`s cache the response is still valid sometimes. I`ve checked it on 50k images and sometimes HEAD request indicates that response is valid while it not supposed to. Otherwise i would use HEAD.

Handy HTTP requests with Curb and Ruby

Dan Sosedoff — Sun, 13 Jun 2010 05:43:49 +0000

While working on one of the projects, i tried to find multi-purpose HTTP request class that can use different network interfaces/ip addresses with retry option (if connection slow or server not responding for some reason).

Here is a small class wrapper build on top of Ruby Curb implemented as a module:

module ApiRequest
  USER_AGENTS = [
    'Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3',
    'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727)',
    'Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.3) Gecko/20100423 Ubuntu/10.04 (lucid) Firefox/3.6.3',
    'Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_3; en-US) AppleWebKit/533.4 (KHTML, like Gecko) Chrome/5.0.375.70 Safari/533.4',
    'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.2) Gecko/20100323 Namoroka/3.6.2',
    'Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100401 Ubuntu/9.10 (karmic) Firefox/3.5.9'
  ]
 
  CONNECTION_TIMEOUT = 10
 
  @@interfaces = []
 
  # get random user-agent string for usage
  def random_agent
    USER_AGENTS[rand(USER_AGENTS.size-1)]
  end
 
  # get random IP/network interface specified in @@interfaces
  def random_interface
    size = @@interfaces.size
    size > 0 ? @@interfaces[rand(size-1)] : nil
  end
 
  # perform request, assign_to - specify network interface/ip
  def perform(url, assign_to=nil)
    puts url
    interface = assign_to.nil? ? self.random_interface : assign_to
    req = Curl::Easy.new(url)
    req.timeout = CONNECTION_TIMEOUT
    req.interface = interface unless interface.nil?
    req.headers['User-Agent'] = self.random_agent
    begin
      req.perform
      if req.response_code == 200
        return req.downloaded_bytes > 0 ? req.body_str : nil
      else
        nil
      end
    rescue Exception
      return nil
    end
  end
 
  # perform request by number of attempts
  def fetch(url, attempts=3)
    result = nil
    1.upto(attempts) do |a|
      result = self.perform(url)
      break unless result.nil?
    end
    return result
  end
end

And sample usage:

class TestRequest
  include ApiRequest
 
  def foo
     body = self.fetch('http://google.com')
  end
end

If module variable “@@interfaces” is array of ip addresses or network interfaces then one of them (randomly selected) will be used to perform request. Also, function “fetch” has parameter “attempts” which set to 3 by default. It means that operation will be invoked n times until result is downloaded from url. Otherwise – it returns nil.
Function perform has a parameter “assign_to” (which it not used in “fetch” function) that allows to bind request to specified interface. It is useful if you have situation when you might use different workers that bound to exact interface or just one that uses random ip`s. Also, class ApiRequest has a list of user agents which it uses randomly for each performed request.

Pastie: http://pastie.org/private/j19j3hbebte9bjqaydslmg

Making HTTP requests from different network interfaces with Ruby and Curb

Dan Sosedoff — Thu, 10 Jun 2010 04:31:17 +0000

At some point you will find that you have reached requests per IP limit while using some API or crawling resources. And if you`re doing it via standard Net::HTTP you`ll face the problem that you cannot assign request class to specified network interface (or IP). Bummer? No. Even if you cant do it with core class you might take a look on Curb – libcurl ruby binding. It has everything that you need to make regular get/post/etc requests. And of course – easy.

A simple example (real ip`s are changed):

require 'rubygems'
require 'curb'
 
ip_addresses = [
  '1.1.1.1',
  '2.2.2.2',
  '3.3.3.3',
  '4.4.4.4',
  '5.5.5.5'
]
 
ip_addresses.each do |ip|
  req = Curl::Easy.new('http://www.ip-adress.com/')
  req.interface = ip
  req.perform
  result_ip = req.body_str.scan(/<h2>My IP address is: ([\d\.]{1,})<\/h2>/).first
  puts("for #{ip} got response: #{result_ip}")
end

Output (ip`s are changed):

for 1.1.1.1 got response: 1.1.1.1
for 2.2.2.2 got response: 2.2.2.2
for 3.3.3.3 got response: 3.3.3.3
for 4.4.4.4 got response: 4.4.4.4
for 5.5.5.5 got response: 5.5.5.5

At least its working. Havent done any performance tests.
Sample on pastie: http://pastie.org/private/afxlcuk1npwjov3wer5hw

Making colorized console output with Ruby

Dan Sosedoff — Wed, 02 Jun 2010 03:23:04 +0000

If you develop some console application you might want your output be more informative, have different colors for operations or logging purposes. It is possible to do with general ANSI escape codes, which are supported by most common console terminals.

The ASCII escape structure is pretty simple. It begins with “ESC” symbol, which is code 27 in ASCII table. Then “[” symbol. Parameters that goes after “[” symbol are separated by “;” and finally ends with closing sequence: “ESC[0m“.

You can extend basic ruby String class with following code:

class String
    # colorize functions
    def red; colorize(self, "\e[1m\e[31m"); end
    def green; colorize(self, "\e[1m\e[32m"); end
    def dark_green; colorize(self, "\e[32m"); end
    def yellow; colorize(self, "\e[1m\e[33m"); end
    def blue; colorize(self, "\e[1m\e[34m"); end
    def dark_blue; colorize(self, "\e[34m"); end
    def pur; colorize(self, "\e[1m\e[35m"); end
    def colorize(text, color_code) "#{color_code}#{text}\e[0m" ; end
end

And sample usage code:

puts "Starting some job...".blue
puts "Processing thing 1 [#{"OK".green}]"
puts "Processing thing 2 [#{"FAIL".red}]"
puts "Oooops! This is a warning!".yellow
puts "Another color!".pur

The output:

Nice and useful.

How to test mailers in Sinatra, Rails and Merb

Dan Sosedoff — Tue, 04 May 2010 04:06:12 +0000

Once you need to test mailers within your Sinara, Rails or Merb application you wish to see a real output. No need to setup delivery via SMTP. Just create an executable ruby script somewhere, for example: /usr/bin/fake-sendmail.sh with following content:

$ touch /usr/bin/fake-sendmail.sh 
$ chmod +x /usr/bin/fake-sendmail.sh  # make it executable (will require root priv.)

#!/usr/bin/ruby
path = "/tmp/fake-mailer"
Dir.mkdir(path) if !File.exists?(path)
File.open("#{path}/#{Time.now.to_i}.txt", "w") do |f|
    f.puts ARGV.inspect
    $stdin.each_line { |line| f.puts line }
end

And then configure your mailing system:

1. Sinatra

There is a plugin for Sinatra (ported from Merb, http://github.com/foca/sinatra-mailer),

Sinatra::Mailer.config = {:sendmail_path => "/usr/bin/fake-sendmail.sh"}
Sinatra::Mailer.delivery_method = :sendmail

2. Merb

Edit your development configuration file (config/environments/development.rb)

Merb::BootLoader.after_app_loads do
    Merb::Mailer.delivery_method = :sendmail
    Merb::Mailer.config = { :sendmail_path => '/usr/bin/fake-sendmail.sh' }
end

3. Rails.

Edit your development environment file with following options:

config.action_mailer.delivery_method = :sendmail 
config.action_mailer.sendmail_settings = {:location => "/usr/bin/fake-sendmail.sh"}

Jabber bot with Ruby

Dan Sosedoff — Wed, 20 May 2009 22:20:39 +0000

Ruby has very powerful tools to create random jabber bots with XMPP protocol. In this article i`ll show just a small sample with a few commands available.

I got xmpp4r-simple library from Google Code page – http://code.google.com/p/xmpp4r-simple/. Its kinda old, not updated since 2006, but the sources are really easy to read and understand, and probably modify.

First, we need to install dependencies (gems):

$ gem install xmpp4r
$ gem install xmpp4r-simple

And now, the actual ruby code:

#!/usr/bin/ruby
require 'rubygems'
require 'xmpp4r'
require 'xmpp4r-simple'
 
$jabber_login = "YOUR_JABBER_ID_HERE" # test@jabber.org
$jabber_password = "YOUR_PASSWORD_HERE" 
$client = nil
 
# create jabber connection
def jabber_connect()
  begin
    conn = Jabber::Simple.new($jabber_login,$jabber_password)
    return conn
  rescue
    return nil
  end
end
 
# send message to jabber client
def jabber_respond(to, msg)
  $client.deliver(to,msg,:chat)	
end
 
# get sender jabber id
def jabber_get_jid(str)
  matches = str.match(/([a-z\d_.\-]{1,32})@([a-z\d.-]{1,32})\//i)
  return "#{matches[1]}@#{matches[2]}"
end
 
# ------------------------------------------------------------------- #
 
# send server time
def app_time(jid)
  jabber_respond(jid, "Server time is: #{Time.now}")
end
 
# send some 'help' :)
def app_help(jid)
  jabber_respond(jid, "Nobody can help you. You`re alone.")
end
 
# process received message
def app_parse_msg(jid, msg)
  cmd = msg.body.strip
  begin
    case cmd
      when /^help$/i then app_help(jid)
      when /^time$/i then app_time(jid)
      when /^jid$/i then jabber_respond(jid, "Your jabber id: #{jid}")
      else
        jabber_respond(jid, "Unknown command. Try something different.")
    end
  rescue Exception => ex
    jabber_respond(jid, "SYSTEM_ERROR: #{ex}")
  end
end
 
# ------------------------------------------------------------------- #
 
puts "Connecting to jabber server..."
$client = jabber_connect()
if $client
  puts "Connected. Waiting for messages..."
  loop do
    $client.received_messages do |message|
      jid = jabber_get_jid(message.from.to_s)
      puts "Received message from #{jid}: #{message.body}"
      app_parse_msg(jid, message)
    end
    sleep 0.1
  end
else
  puts "Cannot connect. Please try again later."
end

I think, the comments in source code are enough to understand what this bot supposed to do. There are 3 commands available: ‘help’, ‘time’, ‘jid’

Download script here – http://files.sosedoff.com/204ab61c/

WebDAV client in ruby

Dan Sosedoff — Sat, 02 May 2009 05:03:30 +0000

Here is a simple example how to make native WebDAV client with Ruby sockets. No additional gems or extensions needed – just all basic classes.

class WebDAV
	attr_reader :host, :port, :protocol, :chunk_size
	@socket = nil
 
	def initialize(host,port=80,protocol='HTTP/1.1',chunk=8096)
		@host = host.to_s
		@port = port.to_i
		@protocol = protocol
		@chunk_size = chunk.to_i
	end
 
	def build_header(method, path, content_length=nil)
		header = "#{method} #{path} #{@protocol} \r\n"
		header += "Content-Length: #{content_length}\r\n" if !content_length.nil?
		header += "Host: #{@host}\r\n"
		header += "Connection: close\r\n\r\n"
		return header
	end
 
	def request(method, path)
		open
		header = build_header(method, path)
		if @socket.write(header) == header.length then
			return @socket.gets.split[1]
		end
	end
 
	def delete(path)
		request('DELETE', path)
	end
 
	def head(path)
		request('HEAD', path)
	end
 
	def mkcol(path)
		request('MKCOL', path)
	end
 
	def put(path, localfile, auto_head=true)
		if !File.exists?(localfile) || !File.readable?(localfile)
			raise "File not exists or not accessible for reading!"
		end
 
		open
 
		datalen = File.size(localfile)
		header = build_header('PUT', path, datalen)
 
		begin
			if @socket.write(header) == header.length then
				written = 0
				File.open(localfile,'r') do |f| 
					until f.eof? do
						written += @socket.write(f.read(@chunk_size))
					end
				end
 
				if written == datalen
					close
					if !auto_head
						return true
					else
						return head(path)
					end
				end
			end
		rescue Exception => e
			puts e
			return false
		end
	end
 
	def open
		begin 
			@socket = TCPSocket.open(@host,@port)
			return true
		rescue Exception => e
			puts e
			return false
		end
	end
 
	def close
		begin
			return @socket.close
		rescue 
			return false
		end
	end
end

This class supports only basic http/dav methods (PUT, DELETE, MKCOL, HEAD) and can be extended very easily and designed to work with all files, reading them by small chunks (default is 8096 bytes).
Im using this class sometimes with nginx.

Deps:

require 'socket'
require 'digest'

Usage:

# create connection
conn = WebDAV.new('your.host.com')
 
# upload file (without autocheck), return true/false value
result = conn.put('/test.mp3','/home/.../..../..../file.mp3', false)
 
# upload file with autocheck, returns http response code (201, 404, ... ) so you`ll know what exactly happened
result = conn.put('/test2.mp3','/home/.../file.mp3')

Also, here is a wrapper class to produce MD5, SHA1 file hashes that supports big files.

class FileHash 
	def self.md5(path)
		d = Digest::MD5.new
		File.open(path,'r') do |f| 
			d.update(f.read(8192)) until f.eof?
		end
		return d.hexdigest
	end
 
	def self.sha1(path)
		d = Digest::SHA1.new
		File.open(path,'r') do |f| 
			d.update(f.read(8192)) until f.eof?
		end
		return d.hexdigest
	end
end

Usage:

FileHash.md5('/path/to/file')
FileHash.sha1('/path/to/file')

This webdav class not pretending to be stable in production environment, but can be useful for some “one-time” tasks with less code.

inet_ntoa and inet_aton in Ruby

Dan Sosedoff — Thu, 16 Apr 2009 07:22:15 +0000

Here is two small functions to convert IP addresses from string representation to integer and vice versa.

def inet_aton(ip)
    ip.split(/\./).map{|c| c.to_i}.pack("C*").unpack("N").first
end
 
def inet_ntoa(n)
    [n].pack("N").unpack("C*").join "."
end