Arun Gupta's Blog

TOTD #52: Getting Started with Merb using GlassFish Gem

1. Install Merb: Merb 1.0 has some native dependencies in DataMapper and so cannot be installed as is with JRuby. However since Merb is ORM-agnostic, ActiveRecord can be installed as ORM layer. "gem install merb" uses DataMapper as the default ORM so a Merb installation in JRuby (for now) is:
   
   

   ~/tools/jruby-1.1.5 >gem install merb-core merb-more merb_activerecord JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL Successfully installed extlib-0.9.8 Successfully installed abstract-1.0.0 Successfully installed erubis-2.6.2 Successfully installed json_pure-1.1.3 Successfully installed rack-0.4.0 Successfully installed mime-types-1.15 Successfully installed thor-0.9.8 Successfully installed merb-core-1.0 Successfully installed ZenTest-3.11.0 Successfully installed RubyInline-3.8.1 Successfully installed sexp_processor-3.0.0 Successfully installed ParseTree-3.0.2 Successfully installed ruby2ruby-1.2.1 Successfully installed merb-action-args-1.0 Successfully installed merb-assets-1.0 Successfully installed merb-slices-1.0 Successfully installed merb-auth-core-1.0 Successfully installed merb-auth-more-1.0 Successfully installed merb-auth-slice-password-1.0 Successfully installed merb-auth-1.0 Successfully installed merb-cache-1.0 Successfully installed merb-exceptions-1.0 Successfully installed highline-1.5.0 Successfully installed diff-lcs-1.1.2 Successfully installed templater-0.4.0 Successfully installed merb-gen-1.0 Successfully installed haml-2.0.4 Successfully installed merb-haml-1.0 Successfully installed merb-helpers-1.0 Successfully installed mailfactory-1.4.0 Successfully installed merb-mailer-1.0 Successfully installed merb-param-protection-1.0 Successfully installed addressable-1.0.4 Successfully installed data_objects-0.9.6 Successfully installed dm-core-0.9.6 Successfully installed dm-migrations-0.9.6 Successfully installed merb_datamapper-1.0 Successfully installed merb-more-1.0 Successfully installed merb_activerecord-0.9.13 39 gems installed Installing ri documentation for json_pure-1.1.3... Installing ri documentation for rack-0.4.0... Installing ri documentation for mime-types-1.15... . . . Installing RDoc documentation for dm-migrations-0.9.6... Installing RDoc documentation for merb_datamapper-1.0... Installing RDoc documentation for merb_activerecord-0.9.13...

   
   It would be nice if this can be further simplified to "gem install merb --orm activerecord" or something similar.
   
2. Create a Merb application:  A "jump start" Merb application created using "merb-gen app" uses ERB templating and DataMapper for ORM. But as mentioned earlier DataMapper does not work with JRuby (at least for now) so a Merb application needs to be created using "merb-gen core". This command creates a Merb application with Ruby-on-Rails like structure and allows to plugin templating engine and ORM frameworks.
   
   Lets create our first Merb application with no ORM and default templating engine as:
   
   

   ~/samples/jruby/merb >merb-gen core hello Generating with core generator:      [ADDED]  gems      [ADDED]  merb.thor      [ADDED]  .gitignore      [ADDED]  public/.htaccess      [ADDED]  doc/rdoc/generators/merb_generator.rb      [ADDED]  doc/rdoc/generators/template/merb/api_grease.js      [ADDED]  doc/rdoc/generators/template/merb/index.html.erb      [ADDED]  doc/rdoc/generators/template/merb/merb.css      [ADDED]  doc/rdoc/generators/template/merb/merb.rb      [ADDED]  doc/rdoc/generators/template/merb/merb_doc_styles.css      [ADDED]  doc/rdoc/generators/template/merb/prototype.js      [ADDED]  public/favicon.ico      [ADDED]  public/merb.fcgi      [ADDED]  public/robots.txt      [ADDED]  public/images/merb.jpg      [ADDED]  Rakefile      [ADDED]  app/controllers/application.rb      [ADDED]  app/controllers/exceptions.rb      [ADDED]  app/helpers/global_helpers.rb      [ADDED]  app/views/exceptions/not_acceptable.html.erb      [ADDED]  app/views/exceptions/not_found.html.erb      [ADDED]  autotest/discover.rb      [ADDED]  autotest/merb.rb      [ADDED]  autotest/merb_rspec.rb      [ADDED]  config/init.rb      [ADDED]  config/rack.rb      [ADDED]  config/router.rb      [ADDED]  config/environments/development.rb      [ADDED]  config/environments/production.rb      [ADDED]  config/environments/rake.rb      [ADDED]  config/environments/staging.rb      [ADDED]  config/environments/test.rb      [ADDED]  public/javascripts/application.js      [ADDED]  public/stylesheets/master.css      [ADDED]  spec      [ADDED]  app/views/layout/application.html.erb

   
   ActiveRecord can be used as pluggable ORM by using the command "merb-gen core --orm activerecord hello". A future blog will cover creating a Merb scaffold using ActiveRecord.
3. Create a new controller as:
   
   

   ~/samples/jruby/merb/hello >merb-gen controller Runners Loading init file from /Users/arungupta/samples/jruby/merb/jruby-1.1.5/samples/merb/hello/config/init.rb Loading /Users/arungupta/samples/jruby/merb/jruby-1.1.5/samples/merb/hello/config/environments/development.rb Generating with controller generator: Loading init file from /Users/arungupta/samples/jruby/merb/jruby-1.1.5/samples/merb/hello/config/init.rb Loading /Users/arungupta/samples/jruby/merb/jruby-1.1.5/samples/merb/hello/config/environments/development.rb      [ADDED]  app/controllers/runners.rb      [ADDED]  app/views/runners/index.html.erb      [ADDED]  spec/requests/runners_spec.rb      [ADDED]  app/helpers/runners_helper.rb

   
   Notice the convention of controller name is a plural word and starting with a capital letter.
4. Edit application
1. Edit "app/controllers/runners.rb" and change the "index" action such that it looks like:
   
   

   def index     @message = "Miles to go ..."     render   end

2. Edit "app/views/runners/index.html.erb" and add "<br><%= @message %>" as the last line.
5. Run application:  Running a Merb application using the Gem is pretty straight forward. If JRUBY_HOME/bin is in PATH, just type the command "glassfish" in the application directory and now you are running a Merb application using GlassFish. The application is accessible at "http://localhost:3000" and the output looks like:
   
   
   
   The controller is accessible at "http://localhost:3000/runners" and the output is:
   
   

Comments

• Hi Arun! Thanks for the tutorial.
  I tried it with merb-1.1.0 and jruby-1.1.5 and it worked. The only problem I can not specify environment variable. It looks like -e option have no effect.

  Posted by: kolach on November 25, 2008 at 02:23 PM

• Thanks kolach, this is a known issue as described at: https://glassfish.dev.java.net/issues/show_bug.cgi?id=6767. It has been fixed and will be available during next gem refresh (coming soon).

  Posted by: arungupta on November 25, 2008 at 02:40 PM

• Good. I'm looking forward the update.

  Posted by: kolach on November 26, 2008 at 05:17 AM

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