This blog provides how you can get started with Merb [1] on JRuby 1.1 RC3 [2].

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 [3] 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 [4]. 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 [5] 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 [6].
• Try Java Persistence API as the pluggable ORM.