The Loop

Step 1

Run the rake task to freeze rails 2.0.2 into the project so your not reading from gems:

rake rails:freeze:gems

Step 2

Remove the database.yml file from RAILS_ROOT/config/

Step 3

Change line 21 in RAILS_ROOT/config/enviroment.rb to:

config.frameworks -= [ :active_record ]

Bobs your uncle, that should be it!

Just a quick note that I have refactored the code base for the XMPie ICP extension for Merb 0.9.2 and added some extra cool things that are inherited by the ICP subclasses.

Now, its possible to add validation into the model subclass. Lets say we have a feild defined in our uPlan called ‘email’ and ‘user_name’. I need the ‘user_name’ field to be required, which you can now do like so:

class Visitor < Xmpie::Icp::Base
  validates_presence_of :user_name
end

# in your controller...
@visitor.valid? # => true if has a user_name, otherwise false

All exciting stuff! When XMPie make ICP a more viable persistance tier, then this will no doubt be the quickest and slickest way to implement front ends in. Furthermore, with the Engine Yard team working on mod_rubinus then we should see ruby web application performance finally get where it needs to be.

Further to my article about God, and using it for watching Merb it seemed like a good idea that I also post my capistrano recipe so people can get the complete picture :)

# MIT License
# 
# Copyright (c) 2008, Tim Perrett
# 
# Permission is hereby granted, free of charge, to any person 
# obtaining a copy of this software and associated 
# documentation files (the "Software"), to deal in the Software
# without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, 
# and/or sell copies of the Software, and to permit persons 
# to whom the Software is furnished to do so, subject to the 
# following conditions:
# 
# The above copyright notice and this permission notice shall 
# be included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 
# ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 
# TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 
# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 
# SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR 
# ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE 
# OR OTHER DEALINGS IN THE SOFTWARE.

set :application, "domain.com" 

set :repository, "svn://yourrepo.com/path/to/repo" 

# Set your SVN and SSH User
set :user, "sshuser" 
set :svn_user, "svnuser" 
#Set the full path to your application on the server
set :deploy_to, "/path/to/your/#{application}" 

# define your servers
role :app, "domain.com" 
role :web, "domain.com" 
role :db, "domain.com", :primary => true

desc "Link in the production extras" 
task :after_update_code do
  run "ln -nfs #{shared_path}/log #{release_path}/log" 
end

desc "Merb it up with" 
deploy.task :restart do
  # you need to add restart tasks for each port you plan 
  # to run merb on. Whilst this is a little long winded, 
  # it will ensure uptime compared to the sledge hammer
  # than is #{current_path}/script/stop_merb
  run "(cd #{current_path}; merb -k 4006); sleep 1; \
  #{current_path}/script/merb -u timperrett -G timperrett \
  -M #{current_path}/config/merb.yml -p 4006 \
  -e production -d" 
  run "(cd #{current_path}; merb -k 4007); sleep 1; \
  #{current_path}/script/merb -u timperrett -G timperrett \
  -M #{current_path}/config/merb.yml -p 4007 \
  -e production -d" 
end

Any problems, let me know :)

Before you start reading, this post only applies for Merb 0.5.3, any newer version is totally untested

When you take Merb out into the wild, it does, unfortunatly, suffer a lot of the same problems as the mongrel handler than runs Rails.

There is however a saviour out there – God – To clarify, im not talking about the man upstairs; rather the process monitoring tool which rocks at restarting bloated mongrel processes on *nix based OS.

The Merb handler does not have any way of restarting a running cluster, so you physically have to stop, then start a new merb process. This is somewhat out of sync with how the god process handling and restarting works in that you define start, stop and critically, restart paramaters. To get around this we have to use a hacky sleep then start method – its not ideal, but hey, it works :)

Rather than letting merb handle the process forking, what were going to do is let God handle the writing of Pids and managing of the process. Ok, less of all this talk and lets take a look at some configuration code for the God configuration.

# MIT License
# 
# Copyright (c) 2008, Tim Perrett
# 
# Permission is hereby granted, free of charge, to any person 
# obtaining a copy of this software and associated 
# documentation files (the "Software"), to deal in the Software
# without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, 
# and/or sell copies of the Software, and to permit persons 
# to whom the Software is furnished to do so, subject to the 
# following conditions:
# 
# The above copyright notice and this permission notice shall 
# be included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 
# ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 
# TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 
# PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 
# SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR 
# ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE 
# OR OTHER DEALINGS IN THE SOFTWARE.

SITE_LOCATION = "/var/www/sites/domain.com" 
MERB_ROOT = "#{SITE_LOCATION}/current" 
MERB_CONFIG = "#{SITE_LOCATION}/shared/config/merb.yml" 
MERB_ENVIROMENT = 'production'
PROCESS_USER = 'timperrett'
PROCESS_GROUP = 'timperrett'

%w{4006 4007}.each do |port|  
  God.watch do |w|

    pid_path = File.join(MERB_ROOT, 'log',"merb.#{port}.pid")

    w.name = "merb-#{port}" 
    w.interval = 30.seconds # default
    w.start = "#{MERB_ROOT}/script/merb -u #{PROCESS_USER} \
    -G #{PROCESS_GROUP} -M #{MERB_CONFIG} -p #{port} \
    -e #{MERB_ENVIROMENT} -d" 
    w.log = "/home/timperrett/godmerb.log" 
    w.stop = "(cd #{MERB_ROOT}; merb -k #{port})" 
    w.restart = "(cd #{MERB_ROOT}; merb -k #{port}); sleep 1; \
    #{MERB_ROOT}/script/merb -u #{PROCESS_USER} -G \
    #{PROCESS_GROUP} -M #{MERB_CONFIG} -p #{port} \
    -e #{MERB_ENVIROMENT} -d" 
    w.start_grace = 5.seconds
    w.restart_grace = 20.seconds
    w.pid_file = File.join(MERB_ROOT, "log/merb.#{port}.pid")
    # w.group = "merbs" 
    w.behavior(:clean_pid_file)

    w.start_if do |start|
      start.condition(:process_running) do |c|
        c.interval = 10.seconds
        c.running = false
      end
    end

    w.restart_if do |restart|
      restart.condition(:memory_usage) do |c|
        c.above = 51.megabytes
        c.times = [3, 5] # 3 out of 5 intervals
      end

      restart.condition(:cpu_usage) do |c|
        c.above = 50.percent
        c.times = 5
      end
    end

    w.lifecycle do |on|
      on.condition(:flapping) do |c|
        c.to_state = [:start, :restart]
        c.times = 5
        c.within = 5.minute
        c.transition = :unmonitored
        c.retry_in = 5.minutes
        c.retry_times = 5
        c.retry_within = 2.hours
      end
    end

  end
end

Im not sure that this is ideal, but it certainly seems to work for me and importantly keeps the site running without problems – which is a dang sight better than them becoming unresponsive!

I hope this might help someone, somewhere….

Well, I got board – what can I say!

If you have a signup.to account you can enjoy really seamless intergration with merb for sending messages :)

All you need to to send a SMS is write something like this in one of your controllers:

send_sms(ExampleMessenger, 
               :some_method, 
               { :from => "02UK", 
                 :to => "44123456789" })

Thats pretty dang sweet; its also all very MVC, using its own messaging controllers (complete with generators) and ERB files for the message content. Lovely.

If anyone gets use out of it, I would really love to hear about it – download the gems here

Firstly, I read this blog post by Zed Shaw. Quite frankly I was disgusted that someone who has given so much to our community has been treated so poorly by prominent figures within our very inner circles and the major vendors. I must point out I do not know Zed, Ive never met him, nor will I likely ever meet him, but yet he helped me many times way back in the early days of mongrel, as im sure he did with countless others – and for that, he gets my respects and applause.

His blog posts about the problems with Rails echoed conversations I have had multiple times of late with various other developers and architects. People feel rails is bloated and has a lot of inefficiencies – which is true, and whilst 2.1 is leaner, it could still do with a good going over at fat camp… That sounds bad I admit, but I am not ignorant of the fact that we do have an awful lot to thank Rails (and DHH especially) for – the ideas behind Rails have changed the way the whole development community look at there working practices from start to finish. The shear magnitude of that is mind-blowing.

Personally, Rails has changed the way I look at code, the way I think and more – this blog is even powered by rails. Despite all that, when I build a Rails project now, I cant help but feel, well, a little bit dirty. Initially in my Rails career I loved the way that the bulk of the complexity was abstracted far far away down the rabbit hole – thats not because I was an incompetent coder – it was just new and exciting, and seemed like such a great idea at the time (like so many other things…). Now however, I feel like we need more; more control, more transparency in our frameworks and tools. Less black boxes and more turner-prize type glass ones!

I ask you the reader one thing: Is it time we said farewell to Rails? Or is it a case of the grass is greener on the other side?

Some of you reading this might be thinking that this is all well and good, but what the hell are we going to use to build our projects. Well, I have been putting a lot of time into the Merb framework recently, and it is, categorically, awesome, not to mention thread safe ;) Working with it feels just, well, better. Ezra has crafted a great framework that has taken heed of Rails’ shortcomings, that my friends can only be a good thing…

Anyway, I’ll be posting some Merb tutorials up here soon, so I hope you will give it a try and let me know how you get on.

Happy coding guys, and farewell Rails, its been emotional!

Well its taken a while to put together, but I am finally reaching the point at which its really useable and sweet to work with. I would love to hear peoples thoughts on this - are you already using the DW controls? If so, what are your thoughts on this new style of working? Is it too limited by way of being too techie?

Its important to note that this framework is 100% cross platform any only requires Ruby, and the RubyGems package management; this screen-cast however was created on OSX Leopard.

MAKE SURE YOU VIEW FULL SCREEN TO READ THE TEXT

Enjoy!

Of late of been writing some nice gems makings heavy use of meta programming. If anyone is looking at doing something similar, I would high recommend you check out these resources:

http://www.infoq.com/presentations/metaprogramming-ruby

http://www.rubyplus.org/

The talk about self and its meaning was extremely interesting - its really surprising how flexible it can be in the right hands :)