Monday, January 2, 2012

Simple Scaffolding for a Dojo Ajax Toolkit application

I've been writing some simple exercises for workshop-style (or solo) training for Dojo Ajax Toolkit, focusing on the strength of Dojo - writing OO-JavaScript applications.



The first exercises is about using Dojo's (classical) require and simple namespacing to create simple widgets, but I've gotten repeated requests for a complete application skeleton - something I understand the need for and which would have helped me quite a bit some years ago as well.

Luckily now there are some.  The guys at Sitepen have written some excellent articles (with much better layout :) here and here which you should definitely check out as well.

My aim here, though is to give you a scaffolding which contains all the structure you need to get started. I've included Dojo 1.7.1  in the latest exercise, which might seems staggeringly stupid, but the reason is that this part of the exercises will go into building and testing, where you actually have to have a downloaded copy.

The exercises (definitely a work in progress) can be found here; https://github.com/psvensson/Dojo-Ajax-Toolkit-Free-Training and here is the Description file of today's app scaffolding sample.

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This exercise show how to make a simple scaffolding of an application in Dojo.
It is not an exercise per se, but shows both a simple CSS layout and how to split up separate parts of the app into subclasses.

This time we are referencing a local copy of Dojo 1.7.1, since subsequent exercises will use both the DOH testing system and the build system, both which are used from the Dojo 'util' folder
and relies on parts of Dojo to run.

I'm still using the old (pre-AMD) style of declaring classes, so Dojo will warn about some things.

The goal is to show in a series of exercises how to create a simple single-page app with Dojo which is:

 1. Object-oriented - splitting functionality across a small class-hierarchy and through a logical namespace
 2. Using a sensible box model CSS layout
 3. Turn-key, so you can just copy the structure and get going modifying stuff as you please.

The page sample.html require's just one class, which is the widget mycustom.MainApp

In the MainApp class, a template is declared which defines the uppermost layout of the application;



<div class="mycustom_box">
<div class="mycustom_top">
<div class="mycustom_left"  dojoType="mycustom.navigator.ui.MenuBar"></div>
<div class="mycustom_right" dojoType="mycustom.common.ui.LoginWidget"></div>
</div>
<div class="mycustom_center">
<div dojoType="mycustom.navigator.ui.ViewPort"></div>
</div>
<div class="mycustom_bottom">
Bottom area
</div>
</div>


The application has three visual parts; A top part which contain a menu widget and a login/out widget, a central part which contains a viewport which can switch between different views, and a bottom part which contain information and links.

Since these different parts are defined in their separate classes, with their separate template files, you get an automatic modularization that makes it less likely that different programmers
step on each others toes when working together (or just one making a 10K lines long file...)

This is a very, very simple scaffolding example which does nothing at all, but is a minimalistic proof of concept of how to start your own non-trivial Dojo application.

The namespace is divided into the main parts 'common' - for classes that can be reused and are hopefully generic, and 'navigator' - for classes that are specifically implementing the logic of this application.

I have called it 'navigator' because Internets. I have meant it to be a small app that let you navigate some space of stuff.

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