IT.Signals

As discussed in the Rails and Sybase Adapative Server Anywhere (SQLAnywhere) article I had to modify the odbc_adapter.rb code to allow the adapter to be used with my SybaseASA DB. Making the change to the adapter code directly is not an acceptable solution and until the developers of the adapter apply the change I had to come up with an alternate solution.

The solution I came up with was to monkey-patch the method responsible for checking the DB type to allow SybaseASA to be seen as a valid DB. I added the following code to my environment.rb:

# Monkeypatch the ODBC Adapter so that it will work with SybaseASA
# see http://odbc-rails.rubyforge.org/index.html
module ActiveRecord
  module ConnectionAdapters
    class ODBCAdapter < AbstractAdapter 
      alias :orig_dbmsNameToSym :dbmsNameToSym

      def dbmsNameToSym(dbmsName, dbmsVer)   
        begin
          # Call original method
          symbl = orig_dbmsNameToSym(dbmsName, dbmsVer)
        rescue ActiveRecord::ActiveRecordError
            # Catch exception if db not found in existing list, check
            # if SybaseASA, if not raise exception
            if dbmsName =~ /adaptiveserveranywhere/i
              symbl = :sqlanywhere
            else
              raise ActiveRecord::ActiveRecordError, "ODBCAdapter: Unsupported database (#{dbmsName})"
            end
        end
        return symbl
      end

    end
  end
end

In a previous article (Sybase DB Adapter) I wrote how I tried to install the Sybase adapter in an attempt to get access to an existing SybaseASA 9.0.2 DB. After doing some research I found that this adapter only works for the Enterprise edition of Sybase (i.e. SybaseASE).

So I needed to find an alternative that would work with SybaseASA or SQLAnywhere. After a lot of searching I came across a group dedicated to this task, at this stage there is not a lot of activity. One of the postings from Bryan Lahartinger proved very helpful, in the article he mentions "odbc-rails". I did a google search and found there is a Ruby project ODBC Adapter for Ruby on Rails / Active Record that has been developing an ODBC adapter for use with Rails.

The latest release has added support for SQLAnywhere so I dowloaded and installed it. There is a home page for this project which provides detailed installation instructions. I do my Rails development on Windows using InstantRails, a quick check confirmed that Christian Werner’s ODBC module comes preloaded with InstantRails so I did not have to install it separately. I downloaded the gem file for V2.0 from rubyforge and installed it using:

gem install -l activerecord-odbc-adapter-2.0.gem –include-dependencies

I setup my database.yml file to use the DSN I had previously defined to access the DB, i.e.

development:
  adapter: odbc
  dsn: mydatabase
  username: uid
  password: pwd

I started my server which loaded without any problem but when I tried to run my application I got the following error:

ODBCAdapter: Unsupported database (adaptiveserveranywhere)

As SybaseASA is the same as SQLAnywhere I changed the following line in odbc_adapter.rb (line #:1585) to get me going from:

elsif dbmsName =~ /SQLAnywhere/i

to:

elsif dbmsName =~ /SQLAnywhere/i or dbmsName =~ /adaptiveserveranywhere/i

So far everything seems to working without any problems, I’ve asked if it will be possible to get this change added to the gem, if not I will need to monkeypatch the source. Next I will attempt to do an install under Suse Linux as this is where the application will ultimately reside.

Update: I’ve now added the monkey-patch to my application see Rails ODBC Adapter with Sybase Adaptive Server Anywhere (SybaseASA)

 Update: This adapter only works with the enterprise edition of Sybase (i.e. Sybase ASE) not with SQLAnywhere (Sybase ASA)

One of my Rails projects require me to connect to a Sybase ASA database, I quickly figured out that I needed to install the sybase adapter as in Rails 2.0.2 these and some of the other databases have been pulled out of Rails core. According to the information in this article you can achieve this by using this command:

gem install activerecord-sybase-adapter

When I tried this I got the following error:

ERROR:  could not find activerecord-database-adapter locally or in a repository

The only way I got it to work was to use the -s option ("Use URL as the remote source for gems"), i.e.

gem install activerecord-sybase-adapter -s http://gems.rubyonrails.org

We have been using the refresh_to plugin in one of our projects. For those who do not know, the refresh_to plugin adds a refresh_to method to the ActionController::Base which allows us to avoid the IE security warnings when moving from a secure SSL page to an insecure page.

We are using rspec for our testing and when I went to write some tests to test some code that uses the refresh_to method I found out that the standard redirect_to rspec matcher does not work with refresh_to. The same problem exist for the standard test method assert_response :redirect and assert_redirected_to my_url, but the plugin does supply replacement tests for these methods. The problem is that it does not supply a replacement for the rspec matcher so I had to write my own. 

# The standard rspec redirect_to matcher does not work with the refresh_to
# plugin methods, i.e. refresh_to and refresh_back_or_default.
# This is also the case with the with the standard Rails functional
# tests - assert_response :redirect and assert_redirected_to my_url.
# The plugin has replacement test methods for these but they do not
# have an rspec replacement for redirect_to so I’ve had to write my own.
#
module Spec
  module Rails
    module Matchers
     
      class RefreshTo  #:nodoc:

        def initialize(controller, expected)
          @expected = expected
          @controller = controller
        end

        def matches?(response)
          match_data = response.body.match(/<meta http-equiv="refresh" content="0;url=([\S]+)">/)
          return false if (!match_data)
          parts = match_data[1].split("http://test.host")
          @actual = parts.last
          return match()
        end
         
        def match
          case @expected.class.to_s
            when ‘String’
              parts = @expected.split("http://test.host")                      
              @expected = parts.last
              return @actual == @expected
            when ‘Hash’
              @expected = @controller.url_for(@expected)
              return match()
          end         
        end

        def failure_message
          return %Q{expected redirect to #{@expected.inspect}, got redirect to #{@actual.inspect}}
        end

        def negative_failure_message
          return %Q{expected not to be redirected to #{@expected.inspect}, but was}
        end

        def description
          "redirect to #{@actual.inspect}"
        end
      end
     
      # :call-seq:
      #   response.should refresh_to(url)
      #   response.should refresh_to(:action => action_name)
      #   response.should refresh_to(:controller => controller_name, :action => action_name)
      #   response.should_not refresh_to(url)
      #   response.should_not refresh_to(:action => action_name)
      #   response.should_not refresh_to(:controller => controller_name, :action => action_name)
      #
      # Passes if the response is a redirect to the url, action or controller/action.
      # Useful in controller specs (integration or isolation mode).
      #
      # == Examples
      #
      #   response.should refresh_to("path/to/action")
      #   response.should refresh_to("http://test.host/path/to/action")
      #   response.should refresh_to(:action => ‘list’)
      def refresh_to(opts)
        RefreshTo.new(controller, opts)
      end
    end

  end
end 

I’ve now completed the SMERF web site. On the site you will find details about SMERF including documentation, download information and so on. To go to the site now click on this link.

 

Update 11 January 2008: SMERF web site completed.

I’m happy to announce the release of SMERF V0.0.1!

I’m still in the process of setting up the official web site but the source is now available for download. The README file contains a lot of information about the plugin including installation and configuration notes. You can also checkout the documentation in the rdoc directory which includes the API docs and the README in a more readable format.

There are several ways to download SMERF:

Direct download

Get it from RubyForge

Subversion

**Create a new smerf directory in your /vendor/plugins directory and change into the new directory

Check out the stable release

svn checkout http://smerf.rubyforge.org/svn/stable .

or Check out a particular release

svn checkout http://smerf.rubyforge.org/svn/tags/REL-0.0.1 .

or Check out the development code

svn checkout http://smerf.rubyforge.org/svn/trunk .

See the README for details of how to install and configure the plugin.

Until I get my bug tracker sorted out if you have any problems please feel free to contact me on smerf at cascadia dot com dot au.

Enjoy!

 

 

Update 11 January 2008: SMERF web site completed.

Update 9 January 2008: SMERF Released! 

Update 8 January 2008: I’ve completed the documentation and testing. I’ve created a project on RubyForge which is waiting approval. If this is not ready by tomorrow I will make an alternate link available for download, so if all goes well I should have a download available tomorrow.

I am putting the final touches to a new plugin called SMERF which stands for Simple MEta Rails Form. The plugin is a result of me extracting the code I used for one of my projects which I discussed in an earlier article Ruby on Rails Survey Builder.

I’ve spend the past few weeks rewriting parts of it to make it more generic so that it can be used for all sorts of things including survey’s, questionnaires, data collection forms and so on. Some of the important changes I’ve made include

• Allow question validations to be written using Ruby code. You can now create your own validation methods as required, there are also a couple of standard system validation methods that come with the plugin. You can specify any number of validation methods for a question by comma separating each method name, e.g. validation: validate_mandatory_question, validate_date_format
• User responses are now stored in a DB table allowing you to perform analysis on the question responses using SQL.

ToDo V0.2

• Currently there are no tests
• Allow forms to be broken into smaller forms, currently you get all questions on a single form
• Allow the save of user responses as you move from form to form

I’m currently writing a plugin generator that will make installation of the plugin easier, hopefully I’ll have this done very soon. I then need to finish the documentation which is mostly done.

I will keep you informed and let you know when the plugin will be available.

 

In the Rails Cookbook there is an article describing how to clean up stale session records periodically, i.e. 13.14 Cleaning Up Residual Session Records. When I attempted to set this up as described in the book there was a couple of problems.

1. I have a few additional require statements in my config/environment.rb which includes some of my custom classes which I’m serializing.

require ‘app/models/survey_item’
require ‘app/models/survey_group’
…

The problem was that the cron job was failing as it could not find these files so I had to modify the cron job from the suggested

*/10 * * * * ruby /srv/www/htdocs/apps/<appname>/script/runner \
script/runner -e production SessionCleanup.nuke_old_db_session

to

*/10 * * * * cd /srv/www/htdocs/apps/<appname> && ruby script/runner \
-e production SessionCleanup.nuke_old_db_sessions

2. Now my cron job was running but if was deleting all my sessions, it was as if it was comparing the wrong time so the condition was always true. I use UTC time in my application and realised I had to make a slight modification to the function in the environment.rb that deletes the session records to take this into consideration, so I changed the function from:

# Clean up session
class SessionCleanup
  def self.nuke_old_db_sessions
    CGI::Session::ActiveRecordStore::Session.destroy_all(
      [’updated_at < ?’, 20.minutes.ago]
    )
  end
end

to

# Clean up session
class SessionCleanup
  def self.nuke_old_db_sessions
    CGI::Session::ActiveRecordStore::Session.destroy_all(
      [’updated_at < ?’, 20.minutes.ago.utc]
    )
  end
end 

By adding the .utc to 20.minutes.ago fixed the problem.

 

Ok so I’ve finished my new Rails application and it’s now time to deploy, which has turned out to be somewhat more challenging than I thought. I’m deploying to a dedicated host running SuSe 9.3.

Installation check list:

1. Ruby
2. RubyGems
3. Rails
4. Mongrel + Mongrel Cluster
5. Nginx
6. Subversion
7. Capistrano

So roll up your sleeves and lets get into it.

1. Ruby

We will build Ruby using the latest source that we will download from the Ruby web site. Before we can do this we need to do some initial setup which includes making sure the required packages are installed that will allow us to build Ruby from source.

1. Start YAST, Software, Install and Remove Software

2. Check if Ruby is already installed, remove it if it is

3. Install the following packages if they have not already been installed

• zlib-devel
• make
• gcc 
• openssl
• openssl-devel

We then need to download the latest version (1.8.6-p110 at time of writing) of the Ruby source which can be downloaded from the official Ruby web site. Once you have downloaded the source we can start the build process.

Create a temporary directory where we can save the source and do all of our builds:
mkdir /tmp/build

Save the Ruby source file to the new directory and extract all of the files using 
tar zxvf ruby-1.8.6-p110.tar.gz

Change into the new source directory created by the extraction process 
cd ruby-1.8.6-p110

Setup our make files
./configure –prefix=/usr –with–openssl

Build Ruby
make

Install 
sudo make install

Check installation worked
ruby -v
which should return the Ruby version, e.g. ruby 1.8.6 (2007-09-23 patchlevel 110) [i686-linux]

Remove the source files
rm -rf  ruby-1.8.6-p110

2. RubyGems

As we do not want to run Rails without installing RubyGems we need to download the source code and build it. Go to RubyForge and download the latest source code (0.9.4 at time of writing).

Save the source code in the temporary directory we created for Ruby above, i.e.
/tmp/build

Extract the source code using
tar zxvf rubygems-0.9.4.tgz

Change to the source directory created by the extraction process
cd rubygems-0.9.4

Perform the installation
sudo ruby ./setup.rb 

Remove source files
rm -rf rubygems-0.9.4

3. Rails

We can now install Rails which is something you may already have done in your development environment. Use the include-dependencies option to make sure all required files are installed.

Install Rails
sudo gem install rails –include-dependencies 

Verify the installation worked
rails -v
which returns the Rails version number for example Rails 1.2.5

4. Mongrel + Mongrel Cluster

To install Mongrel you will need to have Ruby 1.8.4 (or later) and RubyGems installed.

Install Mongrel
sudo gem install mongrel –include-dependencies

We will be using a cluster of three mongrel processes, you need to decide how many will be suitable for your application. To run a cluster of mongrel processes we need to install the mongrel_cluster gem, for details on this gem see the Mongrel web site.

Install the Mongrel Cluster gem
sudo gem install mongrel_cluster

Now that we have Mongrel and Mongrel Cluster installed we can continue with the configuration. I created a test Rails application to test my setup and make sure everything is working correctly. Later when I install my application I will make the required changes to these configs to work correctly with my "real" application.

Create the Rails application we will use for testing, I’m placing it in the apache root directory under a new apps directory. To find the document root go to /etc/apache2 and do a grep on documentroot, i.e. grep -i documentroot
cd /srv/www/htdocs/apps/
rails testapp

Create a user that will be used by the cluster
useradd -system mongrel

Create a cluster configuration file with three processes using ports 8001, 8002, and 8003. This will create a file in the config directory called mongrel_cluster.yml
cd /srv/www/htdocs/apps/testapp
mongrel_rails cluster::configure -p 8001 -e production -a 127.0.0.1 -N 3

I then modified the default configuration file to look like this:
—
user: mongrel
cwd: /srv/www/htdocs/apps/testapp
log_file: /var/log/mongrel.log
port: "8001"
environment: production
group: www
address: 127.0.0.1
pid_file: tmp/pids/mongrel.pid
servers: 3

Change permissions and owner of the Rails application. I am using the same group as used by my Apache system (see /etc/apache2/uid.conf) in my case it’s www
chown -R mongrel:www /srv/www/htdocs/apps/testapp

That takes care of the installation and configuration. We can test to make sure the cluster is working by starting it and connecting to it via a browser.

Start the cluster
cd /srv/www/htdocs/apps/testapp
mongrel_rails cluster::start

Check status of the cluster
cd /srv/www/htdocs/apps/testapp
mongrel_rails cluster::status

Run browser and connect to mongrel ports, you should see the standard Rails startup page
127.0.0.1:8001
127.0.0.1:8002
127.0.0.1:8003

To stop the cluster
cd /srv/www/htdocs/apps/testapp
mongrel_rails cluster::stop

To restart after a code change for example
cd /srv/www/htdocs/apps/testapp
mongrel_rails cluster::restart 

We need to setup the cluster so that it will be restarted when the server is rebooted. 

Create a new directory and create a new link to the mongrel cluster configuration file we created in the previous step
mkdir /etc/mongrel_cluster
ln -s /srv/www/htdocs/apps/testapp/config/mongrel_cluster.yml \
/etc/mongrel_cluster/testapp.yml

Copy the shell script supplied when the mongrel cluster gem was installed to the init.d directory. The shell script allows us to control the cluster including start, stop, status, and restart.
cp /usr/lib/ruby/gems/1.8/gems/mongrel_cluster_1.0.5/resources/mongrel_cluster \
/etc/init.d/
chmod +x /etc/init.d/mongrel_cluster
Usage: /etc/init.d/mongrel_cluster <status|start|stop|restart>

Add the mongrel cluster as a service
Add the service: chkconfig mongrel_cluster 35
To check the service: chkconfig –list mongrel_cluster
To delete the service: chkconfig –del mongrel_cluster

There was one modification I had to make to the mongrel_cluster script to get it to work without any errors: 
Edit: /etc/init.d/mongrel_cluster
Change: chown $USER:$USER $PID_DIR
To: chown $USER:$GROUP $PID_DIR  

5. Nginx

Now that we have a working mongrel cluster running three mongrel processes how are we going to do the load balancing for these processes? I initially looked at using Apache 2.2 + mod_proxy_balancer but as SuSe 9.3 does not have any pre-built packages for 2.2 and I did not want to face the daunting task of building Apache myself I had to look at some alternatives.

I initially considered Pen and Pound but then came across Nginx which seems to have a lot of positive feedback from users. From what I have read it seems that it only requires a small amount memory and is as fast if not faster than mod_proxy_balancer. So I decided to give it a try and so far I’ve been very happy with it.

Before we can install nginx we need to install some packages required during the build process.

1. Start YAST, Software, Install and Remove Software

2. Install the following packages if they have not already been installed

• pcre
• pcre-devel
• pcre++-devel
• openssl
• openssl-devel

I found that these packages where not available on my installation CD so I used packages I found using rpmfind. I connected to this site from the SuSe machine using Konqueror, which when I clicked on the required package, the package information window was displayed allowing installation via YAST.

We can now build and install nginx, one point to note is that I’m using the latest snapshot which includes the upstream_fair changes as discussed in Ezra Zygmuntowicz article A Fair Balancer for Nginx and Mongrel 

Download snapshot from the link below, save the file in the /tmp/build directory
http://git.localdomain.pl/?p=nginx.git;a=shortlog;h=upstream_fair

Extract all files 
tar xzvf nginx-x.x.xx.tar.gz

Change to the extracted source directory
cd nginx-x.x.xx 

Setup our make files
./configure –with-http_ssl_module –prefix=/usr

Build nginx
make

Install
sudo make install

Check installation worked
nginx -v
which should return the nginx version, e.g. nginx version: nginx/0.5.32

Remove the source files
rm -rf  nginx-x.x.xx

Now we need to configure nginx to work with our Rails application, to do this I used a modified version of  Ezra Zygmuntowicz configuration file as described in the Nginx, my new favorite front end for mongrel cluster article. The other change I made to the configuration file was to include the performance improvement tip described in another of Ezra’s articles New Nginx conf with optimization.

Create the nginx.conf file in the test Rails application config directory

I changed the ownership and rights of this file to be the same as the other config files, i.e.
chmod 664 nginx.conf
chown mongrel:www nginx.conf

Test nginx config file
cd /srv/www/htdocs/apps/testapp
nginx -t -c config/nginx.conf 

Start nginx using the new config file
cd /srv/www/htdocs/apps/testapp
nginx -c config/nginx.conf

Stop nginx
ps aux | grep nginx
kill -15 <pid>
where <pid> is the pid of the master process

Test nginx is working correctly, start a browser and connect to nginx using the port you specified in the config file listen directive, i.e. listen 80;. You should see the standard Rails welcome page.

We now need to setup nginx to run as a service so that it will be restarted when the server is rebooted. To do this I modified a script that I found in a slicehost article Ubuntu LTS - adding an ngnix init script, here is my modified version which I’m sure can be improved on but for now it does what I need it to do. Create this script in the /etc/init.d directory in a file called nginx.

#! /bin/sh

PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DAEMON=/usr/sbin/nginx
NAME=nginx
DESC=nginx
PIDFILE=/usr/logs/$NAME.pid
DAEMON_CONFIG=/etc/nginx/nginx.conf

test -x $DAEMON || exit 0

set -e

case "$1" in
  start)
        echo -n "Starting $DESC: "       
        start-stop-daemon –start –quiet –pidfile $PIDFILE \
                –exec $DAEMON — -c $DAEMON_CONFIG
        echo " started"
        ;;
  stop)
        echo -n "Stopping $DESC: "
 if [ -f $PIDFILE ]; then
                kill -15 `cat $PIDFILE 2>/dev/null`
        fi
        echo " stopped"
        ;;
  restart|force-reload)
        echo -n "Restarting $DESC: "
 if [ -f $PIDFILE ]; then
                kill -15 `cat $PIDFILE 2>/dev/null`
        fi
        sleep 1
        start-stop-daemon –start –quiet –pidfile $PIDFILE \
                –exec $DAEMON — -c $DAEMON_CONFIG
        echo " restarted"
        ;;
  status)
        echo "Status $DESC: "
        ps aux | grep -v grep | grep -v /bin/sh | grep $NAME
        ;;
  *)
        N=/etc/init.d/$NAME
        echo "Usage: $N {start|stop|status|restart}" >&2
        exit 1
        ;;
esac

exit 0

Steps to configure nginx as a service.

Create a new directory
mkdir /etc/nginx

Create a link to the nginx.conf file in the test Rails application config directory
ln -s /srv/www/htdocs/apps/testapp/config/nginx.conf \
/etc/nginx/nginx.conf

Make the script executable
chmod +x /etc/init.d/nginx
Usage: /etc/init.d/nginx <status|start|stop|restart>

Add it as a service
Add the service: chkconfig nginx 35
To check the service: chkconfig –list nginx 
To delete the service: chkconfig –del nginx

 

 

In  an attempt to see if I can get my "Ruby and Rails Naming Conventions" article back on Google I’ve created this entry to see if it gets listed.

Click on the link to access the actual article Ruby and Rails Naming Conventions

Sorry for the inconvenience.