Project: Trellis

Trellis is a component-based Web Application Framework written in Ruby and based on Rack. Its main goal is to bring component-driven development to the micro-framework world. Trellis applications are composed of pages, pages have components, components emit events, pages and components can listen and handle events. Trellis aims to be a (close to) zero-configuration framework

It draws inspiration from:

Ruby Web Frameworks

Rails
Camping
Merb
Iowa
Sinatra

Java Web Frameworks

Tapesty
Wicket

Others

Seaside

Goals

Accomplished goals are marked with a (*)

- Pure HTML templates or in-line template creation with Markaby, HAML, erubis, Markdown and Textile
- To abstract away the request-response nature of web development and replace
with events and listeners
- Reusable, extensible components including invisible components (behavior
providers), tags (stateless components) or stateful components
- Easy component composition and markup inheritance
- Multi-threading support
- Heavy CoC :-) (Convention Over Configuration) ala Rails
- No static code generation, no generators, just a Ruby file!
- Component Libraries as Gems
Solid Ajax support attached to the event model using a single* massively tested Ajax framework/toolkit such as JQuery
Skinnable components a la DotNet. That is the ability to apply a theme to a page and cascade that to the contained components
Support for continuations in a componentized fashion (maybe)
CRUD behaviours for Pages/Components and using Datamapper under the covers
Web-based debugging and administration of the application similar to what Seaside provides

Development Goals (To-do’s)

Keep the core framework in a single file
Keep the core components in another file
I have not done anything about exception handling (didn’t wanted to litter the code base). Currently I’m always sending an HTTP 200 back or I’m just letting the app blow chuncks and showing rack’s exception page
Radius usage is really entrenched in the current component implementation need to clean it up
Currently Trellis uses the Mongrel Rack Adapter. In the near future the particular web server would be configurable (one of the reasons to use Rack)

Classes

Trellis::Application: Base case for all Trellis applications
Trellis::Page: Base class for all application Pages
Trellis::Renderer: Renders XML/XHTML tags in the markup using Radius
Trellis::Router: Encapsulated the base route for a page
Trellis::Component: Base class for all Trellis components (work in progress)
Trellis::DefaultRouter: Encapsulates the default routing logic

Notes::

Event model is pretty shallow right now. Basically events are just a convention of how the URLs are interpreted which results on a page method being invoked. A given URL contains information about the target page, event, source of the event and possible context values.This information is used to map to a single method in the page.
Navigation is a la Tapestry; Page methods can return the instance of a injected Page or they can return self in which case the same page is re-rendered.
Components can register their event handlers with the page. The page wraps the event handlers of the contained components and dispatches the events to the component instance.
Currently the Application is a single object, the multi-threading (which I had nothing to do with is provided by Rack) happens in the request dispatching.
Trellis is not a managed framework like Tapestry, in that sense it is more like Wicket. Pages instances are just created when needed, there is no pooling, or any of the complexity involved in activating/passivating objects to a pool.

Installation

gem install trellis

A Trellis application consists of the Application class; a descendant of Trellis::Application and one or more pages; descendants of Trellis::Page. The Application at a minimum needs to declare the starting or home page:

module Hello
  class HelloWorld < Trellis::Application
    home :home
  end

  class Home < Trellis::Page 
    template do html { body { h1 "Hello World!" }} end
  end
end

To run the above application simply add the line:

Hello::HelloWorld.new.start

That will start the application on Mongrel running on port 3000 by default. To run on any other port pass the port number to the start method like:

Hello::HelloWorld.new.start 8282

Required Gems

rack => rack.rubyforge.org mongrel => mongrel.rubyforge.org radius => radius.rubyforge.org builder => builder.rubyforge.org paginator => paginator.rubyforge.org extensions => extensions.rubyforge.org haml => haml.hamptoncatlin.com markaby => code.whytheluckystiff.net/markaby nokogiri => nokogiri.org/ facets => facets.rubyforge.org/ directory_watcher => rubyforge.org/projects/codeforpeople erubis => www.kuwata-lab.com/erubis/

LICENSE:

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Contact

Author: Brian Sam-Bodden & the Folks at Integrallis
Email: [email protected]
Home Page: trellisframework.org
License: MIT Licence (www.opensource.org/licenses/mit-license.html)