alexpetrov/obvious_status

An Obvious Architecture implementation of a twitter style status update app.

Obvious Status

Status is an implementation of a twitter style status update app based on the Obvious Architecture (http://obvious.retromocha.com/).

The purpose of this project is be an example app to help explain the concepts of Obvious.

Thanks to Obvious, it was trivially easy to make Status run as a rails app, Sinatra web app, a Sinatra json api, a command line app, and even a desktop app without changing any of the app/ code. Also, the data layer is pluggable, so Status apps can be powered by JSON files, MySQL, MongoDB, or even the Status json api by simply pointing the jack objects at different database plugs.

Basic Structure

Obvious is not traditional MVC. It's a different approach. The business logic and the data persistence are separated into separate folders. The app folder contains your business rules and entities, which would be the M in the MVC pattern. The external folder contains your data persistence layer - ORM's, API's, caching, queues. The delivery folder is where the VC in MVC would live. That is where you find rails, sinatra, desktop app, and a cli apps. Each delivery mechanism is responsible for integrating together app actions and jacks to make the system do things.

Note - in this example app the app folder and external folder live alongside your delivery mechanisms, but you could easily put your app or external jacks/plugs into separate gems.

Running The Tests

To run the tests for the app/ is easy. In the obvious_status project root run:

bundle install
rake rspec

To continuously run the tests using guard, install guard and run:

bundle exec guard

The tests should all be green and run in about 0.02 seconds.

Running The Apps

To make all the apps work, you will need to install the following gems: obvious, json, validation, sequel, moped, mysql, and rest-client. You can comment out the plugs that you don't need if you want to reduce dependencies or have problems installing a particular gem.

To run the rails app run:

cd delivery/rails_app/
bundle install
rails server

To run the web app run:

bundle install
rake server

And navigate to http://localhost:9393/

To run the api app run:

bundle install
rake api

And navigate to http://localhost:9394/

To run the cli app run:

cd delivery/cli
./status.rb

To run the desktop app you will need to install jruby and purple_shoes. After those are installed you would run:

cd delivery/desktop
jruby -J-XstartOnFirstThread --1.9 app.rb

The Development Process

If you look through the commit logs, you can get a better idea of what an Obvious app's development process looks like. You start by sketching out the pseudocode of your app using descriptor files and using the 'obvious generate' command to turn the descriptor files into your project file structure and empty tests. Once you have pending tests, you build out the application entities, actions, and contracts via TDD. Make the tests green! After your tests are green you can make a working implementation by combining your app actions with jacks and plugs in the delivery mechanism - like in your web app.

Status followed that pattern pretty closely. After the app/ folder code was all done and the tests were green, I didn't need to go back and touch it to build the different types of delivery mechanisms or to change databases. If the plugs didn't work, the contracts would raise errors. Once the plugs were written to spec, everything just worked. Since the app actions just return hashes, working with the output in various apps was trivial. No app logic leaked into controllers or views.

The goal of Status was to show that both your delivery mechanism and your database can be decoupled and pluggable if you use the Obvious Architecture. Tests are fast. Development is fun.

If you have questions don't hesitate to tweet me @programminggeek