This blog provides how you can get started with Merb on JRuby 1.1 RC3.

Merb is another MVC framework (just like Rails) but with a pluggable ORM, JavaScript library and Template language. Rails has built-in support for these using ActiveRecord, Script.aculo.us and ERB templates. Making it pluggable keeps the core very lightweight and still providing support for a particular feature using plugins. Another big advantage of Merb is that unlike Rails it's thread-safe.

There are already third party supports for ActiveRecord, DataMapper and Sequel ORMs. I will hopefully be able to build support for Java Persistence API ORM in Merb. Until then, here is how you install and get started with Merb on JRuby 1.1 RC3.

Install Merb on JRuby as:

Macintosh-187:jruby-1.1RC3 arungupta$ bin/jruby -S gem install merb mongrel JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL Updating metadata for 339 gems from http://gems.rubyforge.org ......................................................................................................... ......................................................................................................... ......................................................................................................... ........................ complete Successfully installed abstract-1.0.0 Successfully installed erubis-2.5.0 Successfully installed json_pure-1.1.2 Successfully installed rack-0.3.0 Successfully installed hpricot-0.6-java Successfully installed mime-types-1.15 Successfully installed merb-core-0.9.2 Successfully installed merb-action-args-0.9.2 Successfully installed merb-assets-0.9.2 Successfully installed activesupport-2.0.2 Successfully installed rubigen-1.2.4 Successfully installed merb-gen-0.9.2 Successfully installed merb-haml-0.9.2 Successfully installed merb-builder-0.9.2 Successfully installed mailfactory-1.2.3 Successfully installed merb-mailer-0.9.2 Successfully installed merb-parts-0.9.2 Successfully installed merb-cache-0.9.2 Successfully installed merb-more-0.9.2 Successfully installed merb-0.9.2 Successfully installed gem_plugin-0.2.3 Successfully installed mongrel-1.1.4-java 22 gems installed Installing ri documentation for json_pure-1.1.2... Installing ri documentation for rack-0.3.0... Installing ri documentation for hpricot-0.6-java... Installing ri documentation for mime-types-1.15... Installing ri documentation for merb-core-0.9.2... Installing ri documentation for merb-action-args-0.9.2... Installing ri documentation for merb-assets-0.9.2... Installing ri documentation for activesupport-2.0.2... Installing ri documentation for rubigen-1.2.4... Installing ri documentation for merb-gen-0.9.2... Installing ri documentation for merb-haml-0.9.2... Installing ri documentation for merb-builder-0.9.2... Installing ri documentation for mailfactory-1.2.3... Installing ri documentation for merb-mailer-0.9.2... Installing ri documentation for merb-parts-0.9.2... Installing ri documentation for merb-cache-0.9.2... Installing ri documentation for gem_plugin-0.2.3... Installing ri documentation for mongrel-1.1.4-java... Installing RDoc documentation for json_pure-1.1.2... Installing RDoc documentation for rack-0.3.0... Installing RDoc documentation for hpricot-0.6-java... Installing RDoc documentation for mime-types-1.15... Installing RDoc documentation for merb-core-0.9.2... Installing RDoc documentation for merb-action-args-0.9.2... Installing RDoc documentation for merb-assets-0.9.2... Installing RDoc documentation for activesupport-2.0.2... Installing RDoc documentation for rubigen-1.2.4... Installing RDoc documentation for merb-gen-0.9.2... Installing RDoc documentation for merb-haml-0.9.2... Installing RDoc documentation for merb-builder-0.9.2... Installing RDoc documentation for mailfactory-1.2.3... Installing RDoc documentation for merb-mailer-0.9.2... Installing RDoc documentation for merb-parts-0.9.2... Installing RDoc documentation for merb-cache-0.9.2... Installing RDoc documentation for gem_plugin-0.2.3... Installing RDoc documentation for mongrel-1.1.4-java...

This is so much simpler than couple of weeks ago where all the dependencies had to be explicitly installed. Now create a sample application as:

Macintosh-187:jruby-1.1RC3 arungupta$ cd samples/ Macintosh-187:samples arungupta$ mkdir merb Macintosh-187:samples arungupta$ cd merb/ Macintosh-187:merb arungupta$ ../../bin/jruby -S merb-gen app hello RubiGen::Scripts::Generate       create  app       create  autotest       create  config       create  public       create  spec       create  app/controllers       create  app/helpers       create  app/views       create  app/views/exceptions       create  app/views/layout       create  config/environments       create  public/images       create  public/stylesheets       create  autotest/discover.rb       create  autotest/merb.rb       create  autotest/merb_rspec.rb       create  config/rack.rb       create  config/router.rb       create  config/init.rb       create  public/merb.fcgi       create  spec/spec.opts       create  spec/spec_helper.rb       create  app/controllers/application.rb       create  app/controllers/exceptions.rb       create  app/helpers/global_helpers.rb       create  app/views/exceptions/internal_server_error.html.erb       create  app/views/exceptions/not_acceptable.html.erb       create  app/views/exceptions/not_found.html.erb       create  app/views/layout/application.html.erb       create  config/environments/development.rb       create  config/environments/production.rb       create  config/environments/rake.rb       create  config/environments/test.rb       create  public/images/merb.jpg       create  public/stylesheets/master.css       create  /Rakefile

The top-level directory looks like:

Macintosh-187:hello arungupta$ ls -la total 8 drwxr-xr-x  8 arungupta  arungupta   272 Apr  1 22:20 . drwxr-xr-x  3 arungupta  arungupta   102 Apr  1 22:20 .. -rw-r--r--  1 arungupta  arungupta  3334 Apr  1 22:20 Rakefile drwxr-xr-x  5 arungupta  arungupta   170 Apr  1 22:20 app drwxr-xr-x  5 arungupta  arungupta   170 Apr  1 22:20 autotest drwxr-xr-x  6 arungupta  arungupta   204 Apr  1 22:20 config drwxr-xr-x  5 arungupta  arungupta   170 Apr  1 22:20 public drwxr-xr-x  4 arungupta  arungupta   136 Apr  1 22:20 spec

And finally start the app as:

Macintosh-187:hello arungupta$ ../../../bin/jruby -S merb JRuby limited openssl loaded. gem install jruby-openssl for full support. http://wiki.jruby.org/wiki/JRuby_Builtin_OpenSSL  ~ Loaded DEVELOPMENT Environment...  ~ Compiling routes...  ~ Using 'share-nothing' cookie sessions (4kb limit per client)  ~ Using Mongrel adapter

And the default app is hosted at "http://localhost:4000/" and shown in the browser as:

There is a wealth of information available to get you going after this. Here are couple of things to try:

• If possible, use WARbler to package Merb app and deploy on GlassFish.
• Try Java Persistence API as the pluggable ORM.

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