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Dubious for App Engine

See the published demo:

Introducing Dubious

This is a web framework written in Mirah geared towards running on App Engine. Dubious provide a way to build apps in Mirah, with conventions familiar to Rails developers. Mirah has no runtime dependencies, everything is compiled ahead-of-time. So, Mirah apps have none of the initialization costs associated with JRuby. Dubious supports ERb and uses a simple datastore adapter that uses a syntax similar to DataMapper.

Introducing Mirah

Mirah is a new language with Ruby-inspired syntax that compiles to JVM bytecode. Mirah is statically typed, with local type inference, and a simple macro system. The goal is to make Mirah as expressive as Ruby without introducing any runtime library and while maintaining Java's level of performance. Just write code that looks like Ruby, but reference the Java docs to find out what method calls to make. Mirah uses the Java type system. Join the mirah mailing list to get involved:

Getting Started

Install Dubious(Note: Dubious requires JRuby).

gem install dubious

This will add a `dubious` command that you can create new apps, generate controllers and models etc with.

Once dubious is installed, you can generate an app skeleton.

dubious new my-app
cd my-app

Directory Layout

The layout is based on Rails' with some Java WAR directories, and files geared towards deploying on AppEngine.

  • WEB-INF/app.yaml

contains handlers for different routes, as well as filters and settings for serving static files.

Hacking on Dubious

Setup the Mirah development environment

  • Install JRuby. You can find good instructions on the JRuby website

  • Install the prerelease appengine-sdk gem from

  • Now git clone bitescript, mirah and dubious to your drive

    mkdir -p ~/mystuff; cd ~/mystuff
    git clone
    git clone
    git clone
    git clone
  • Then build and install the gems for Mirah, Bitescript and Dubious

    cd bitescript
    gem build bitescript.gemspec
    gem install bitescript-*
    cd -
    cd mirah
    rake jar:bootstrap
    gem build mirah.gemspec
    gem install mirah-*
    cd -
    cd dubious
    rake gem
    gem install pkg/dubious-*
    cd -

To build the gem (requires RubyGems ~> 1.5.0 to build)

rake package

Developing your App

Install the gem

jgem install dubious

Generate your app

dubious new my-app
cd my-app

There are two ways to develop the app. The first way is to run the build script each time you make a change. The new way is to use the Rakefile. If you are using jruby's rake, the task will watch for source file changes and update the running class files. Otherwise, you need to restart the server when you have changes.

Use the New Rakefile

Run the app locally

jruby -S rake server

Edit the app-id in app.yaml, then publish to

jruby -S rake publish

Apache License 2.0


A Web Framework Written in Mirah for running on AppEngine



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