[Source : www.coding.smashingmagazine.com]
When writing a Web application from scratch, it’s easy to feel like we can get by simply by relying on a DOM manipulation library (like jQuery) and a handful of utility plugins. The problem with this is that it doesn’t take long to get lost in a nested pile of jQuery callbacks and DOM elements without any real structure in place for our applications.
What Is MVC, Or Rather MV*?
These modern frameworks provide developers an easy path to organizing their code using variations of a pattern known as MVC (Model-View-Controller). MVC separates the concerns in an application down into three parts:
- Models represent the domain-specific knowledge and data in an application. Think of this as being a ‘type’ of data you can model — like a User, Photo or Note. Models should notify anyone observing them about their current state (e.g Views).
- Views are typically considered the User-interface in an application (e.g your markup and templates), but don’t have to be. They should know about the existence of Models in order to observe them, but don’t directly communicate with them.
- Controllers handle the input (e.g clicks, user actions) in an application and Views can be considered as handling the output. When a Controller updates the state of a model (such as editing the caption on a Photo), it doesn’t directly tell the View. This is what the observing nature of the View and Model relationship is for.
For this reason we refer to such frameworks as following the MV* pattern, that is, you’re likely to have a View and a Model, but more likely to have something else also included.
At the outset, it isn’t terribly difficult to write an application framework that offers someopinionated way to avoid spaghetti code, however to say that it is equally as trivial to write something of the standard of Backbone would be a grossly incorrect assumption.
There’s a lot more that goes into structuring an application than tying together a DOM manipulation library, templating and routing. Mature MV* frameworks typically not only include many of the pieces you would find yourself writing, but also include solutions to problems you’ll find yourself running into later on down the road. This is a time-saver that you shouldn’t underestimate the value of.
So, where will you likely need an MV* framework and where won’t you?
Good examples of applications that fall into this category are GMail and Google Docs. These applications typically download a single payload containing all the scripts, stylesheets and markup users need for common tasks and then perform a lot of additional behavior in the background. It’s trivial to switch between reading an email or document to writing one and you don’t need to ask the application to render the whole page again at all.
The Challenge Of Choice: Too Many Options?
We refer to the current state of new frameworks frequently popping up as ‘Yet Another Framework Syndrome’ (or YAFS). Whilst innovation is of course something we should welcome, YAFS can lead to a great deal of confusion and frustration when developers just want to start writing an app but don’t want to manually evaluate 30 different options in order to select something maintainable. In many cases, the differences between some of these frameworks can be very subtle if not difficult to distinguish.
TodoMVC: A Common Application For Learning And Comparison
There’s been a huge boom in the number of such MV* frameworks being released over the past few years.
Backbone.js, Ember.js, AngularJS, Spine, CanJS … The list of new and stable solutions continues to grow each week and developers can quickly find themselves lost in a sea of options. From minds who have had to work on complex applications that inspired these solutions (such as Yehuda Katz and Jeremy Ashkenas), there are many strong contenders for what developers should consider using. The question is, what to use and how do you choose?
This week we’re releasing a brand new version of TodoMVC, which you can find more details about lower down in the apps section.
In the near future we want to take this work even further, providing guides on how frameworks differ and recommendations for which options to consider for particular types of applications you may wish to build.
Our Suggested Criteria For Selecting A Framework
Selecting a framework is of course about more than simply comparing the Todo app implementations. This is why, once we’ve filtered down our selection of potential frameworks to just a few, it’s recommend to spend some time doing a little due diligence. The framework we opt for may need to support building non-trivial features and could end up being used to maintain the app for years to come.
- What is the framework really capable of?
Spend time reviewing both the source code of the framework and official list of features to see how well they fit with your requirements. There will be projects that may require modifying or extending the underlying source and thus make sure that if this might be the case, you’ve performed due diligence on the code.
- Has the framework been proved in production?
- Is the framework mature?
We generally recommend developers don’t simply “pick one and go with it”. New projects often come with a lot of buzz surrounding their releases but remember to take care when selecting them for use on a production-level app. You don’t want to risk the project being canned, going through major periods of refactoring or other breaking changes that tend to be more carefully planned out when a framework is mature. Mature projects also tend to have more detailed documentation available, either as a part of their official or community-driven docs.
- Is the framework flexible or opinionated?
Know what flavor you’re after as there are plenty of frameworks available which provide one or the other. Opinionated frameworks lock (or suggest) you to do things in a specific way (theirs). By design they are limiting, but place less emphasis on the developer having to figure out how things should work on their own.
- Have you really played with the framework?
Write a small application without using frameworks and then attempt to refactor your code with a framework to confirm whether it’s easy to work with or not. As much as researching and reading up on code will influence your decision, it’s equally as important to write actual code using the framework to make sure you’re comfortable with the concepts it enforces.
- Does the framework have a comprehensive set of documentation?
Although demo applications can be useful for reference, you’ll almost always find yourself consulting the official framework docs to find out what its API supports, how common tasks or components can be created with it and what the gotchas worth noting are. Any framework worth it’s salt should have a detailed set of documentation which will help guide developers using it. Without this, you can find yourself heavily relying on IRC channels, groups and self-discovery, which can be fine, but are often overly time-consuming when compared to a great set of docs provided upfront.
- What is the total size of the framework, factoring in minification, gzipping and any modular building that it supports?
What dependencies does the framework have? Frameworks tend to only list the total filesize of the base library itself, but don’t list the sizes of the librarys dependencies. This can mean the difference between opting for a library that initially looks quite small, but could be relatively large if it say, depends on jQuery and other libraries.
- Have you reviewed the community around the framework?
Is there an active community of project contributors and users who would be able to assist if you run into issues? Have enough developers been using the framework that there are existing reference applications, tutorials and maybe even screencasts that you can use to learn more about it?
Q: Didn’t Dojo already solve all of this? Why hasn’t it been the dominent solution for developers wishing to build more structured (and more non-trivial) applications?
Many of those features were way ahead of most developers needs. With the emergence of the browser as the dominant application platform, many of the innovations pioneered in The Dojo Toolkit now appear in newer toolkits. MVC was just another package that Dojo has provided for quite some time, along with modular code packages, OO in JS, UI widgets, cross-browser graphics, templating, internationalization, accessibility, data stores, testing frameworks, a build system and much, much more.
Why is Dojo not the dominant toolkit? Its goal was never to be the only choice. The goal was to provide an open collection of tools that could be used with anything else, within projects, and liberally copied into other work as well. Dojo was criticized for being slow and even after that was addressed, it was criticized for being slow. Trying to shake that perception is challenging. It is very hard to document a feature-rich toolkit. There are 175 sub-packages in Dojo 1.8 and over 1,400 modules.
That is not only a challenge from a documentation purpose, it also means that there isn’t one thing that Dojo does. Which is good if you are building software, but very difficult when you are starting out trying to figure out where to start. These are all things we have been trying to work on for Dojo 1.8, in the form of tutorials and significantly improved documentation.
Q: Why should developers still consider Dojo and what ideas do you have lined up for the future of the project? I hear 1.8 will be another major milestone.
In Dojo 1.8, dojox/mvc takes another step towards full maturity. There has been a lot of investment in time, effort, testing and community awareness into the package. It focuses on providing an MVC model that leverages the rest of Dojo. Coupled with dojox/app, an application framework that is designed to make it easier to build rich applications across desktop and mobile, it makes a holistic framework for creating a
client side application.
In the typical Dojo way, this is just one of many viable ways in which to build applications with Dojo.
In 1.8, not only does the MVC sub-module become more mature, it is built upon a robust framework. It doesn’t just give you markup language to create your views, express your models or develop a controller. It is far more then just wiring up some controls to a data source. Because it is leveraging the rest of Dojo, you can draw in anything else you might need.
In Dojo 2.0 we will be looking to take modularity to a new level, so that it becomes even easier to take a bit of this and a bit of that and string it all together. We are also exploring the concepts of isomorphism, where it should be transparent to the end-user where your code is being executed, be it client side or server side and that ultimately it should be transparent to the developer.
The TodoMVC Collection
In our brand new release, Todo implementations now exist for the most popular frameworks with a large number of other commonly used frameworks being worked on in Labs. These implementations have gone through a lot of revision, often taking on board best practice tips and suggestions from framework authors, contributors and users from within the community.
Following on from comments previously made by Backbone.js author Jeremey Ashkenas and Yehuda Katz, TodoMVC now also offers consistent implementations based on an official application specification as well as routing (or state management).
We don’t pretend that more complex learning applications aren’t possible (they certainly are), but the simplicity of a Todo app allows developers to review areas such as code structure, component syntax and flow, which we feel are enough to enable a comparison between frameworks and prompt further exploration with a particular solution or set of solutions.
Our applications include:
- KnockoutJS (MVVM)
For those interested in AMD versions:
And our Labs include:
- SocketStream + jQuery
- Google Web Toolkit
- AngularJS + RequireJS (using AMD)
We feel honored that over the past year, some framework authors have involved us in discussions about how to improve their solutions, helping bring our experience with a multitude of solutions to the table. We’ve also slowly moved towards TodoMVC being almost a defacto app that new frameworks implement and this means it’s become easier to make initial comparisons when you’re reviewing choices.
Frameworks: When To Use What?
To help you get started with narrowing down frameworks to explore, we would like to offer the below high-level framework summaries which we hope will help steer you towards a few specific options to try out.
I want something flexible which offers a minimalist solution to separating concerns in my application. It should support a persistence layer and RESTful sync, models, views (with controllers), event-driven communication, templating and routing. It should be imperative, allowing one to update the View when a model changes. I’d like some decisions about the architecture left up to me. Ideally, many large companies have used the solution to build non-trivial applications. As I may be building something complex, I’d like there to be an active extension community around the framework that have already tried addressing larger problems (Marionette, Chaplin, Aura, Thorax). Ideally, there are also scaffolding tools (grunt-bbb, brunch) available for the solution. Use Backbone.js.
I want something that tries to tackle desktop-level application development for the web. It should be opinionated, modular, support a variation of MVC, avoid the need to wire everything in my application together manually, support persistence, computed properties and have auto-updating (live) templates. It should support proper state management rather than the manual routing solution many other frameworks advocate being used. It should also come with extensive docs and of course, templating. It should also have scaffolding tools available (ember.gem, ember for brunch). Use Ember.js.
I want something more lightweight which supports live-binding templates, routing, integration with major libraries (like jQuery and Dojo) and is optimized for performance. It should also support a way to implement models, views and controllers. It may not be used on as many large public applications just yet, but has potential. Ideally, the solution should be built by people who have previous experience creating many complex applications. Use CanJS.
I want something declarative that uses the View to derive behavior. It focuses on achieving this through custom HTML tags and components that specify your application intentions. It should support being easily testable, URL management (routing) and a separation of concerns through a variation of MVC. It takes a different approach to most frameworks, providing a HTML compiler for creating your own DSL in HTML. It may be inspired by upcoming Web platform features such as Web Components and also has its own scaffolding tools available (angular-seed). Use AngularJS.
I want something that offers me an excellent base for building large scale applications. It should support a mature widget infrastructure, modules which support lazy-loading and can be asynchronous, simple integration with CDNs, a wide array of widget modules (graphics, charting, grids, etc) and strong support for internationalization (i18n, l10n). It should have support for OOP, MVC and the building blocks to create more complex architectures. Use Dojo.
I want something which benefits from the YUI extension infrastructure. It should support models, views and routers and make it simple to write multi-view applications supporting routing, View transitions and more. Whilst larger, it is a complete solution that includes widgets/components as well as the tools needed to create an organized application architecture. It may have scaffolding tools (yuiproject), but these need to be updated. Use YUI.
I want something simple that values asynchronous interfaces and lack any dependencies. It should be opinionated but flexible on how to build applications. The framework should provide bare-bones essentials like model, view, controller, events, and routing, while still being tiny. It should be optimized for use with CoffeeScript and come with comprehensive documentation. Use Spine.
I want something that will make it easy to build complex dynamic UIs with a clean underlying data model and declarative bindings. It should automatically update my UI on model changes using two-way bindings and support dependency tracking of model data. I should be able to use it with whatever framework I prefer, or even an existing app. It should also come with templating built-in and be easily extensible. Use KnockoutJS.
I want something that will help me build simple Web applications and websites. I don’t expect there to be a great deal of code involved and so code organisation won’t be much of a concern. The solution should abstract away browser differences so I can focus on the fun stuff. It should let me easily bind events, interact with remote services, be extensible and have a huge plugin community. Use jQuery.
What Do Developers Think About The Most Popular Frameworks?
As part of our research into MV* frameworks for TodoMVC and this article, we decided to conduct a survey to bring together the experiences of those using these solutions. We asked developers what framework they find themselves using the most often and more importantly, why they would recommend them to others. We also asked what they felt was still missing in their project of choice.
We’ve grouped some of the most interesting responses below, by framework.
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