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Ext JS Application Development Blueprints
Ext JS Application Development Blueprints

Ext JS Application Development Blueprints: Develop robust and maintainable projects that exceed client expectations using Ext JS

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Ext JS Application Development Blueprints

Chapter 2. MVC and MVVM

The problem with software development is that we're always looking for the right way to do things. Each software shop will have their own set of guidelines that indicate how their developers should operate. This is the way that software works: we build a set of ideas that reflect our best thoughts on how things should be developed and the software community learns from these ideas and builds on them. They are formalized into patterns of working and these patterns are shared throughout the development community. In this chapter, we'll talk more about this concept, specifically:

  • The MVC pattern
  • The MVVM pattern
  • The way Ext JS uses both
  • The evolution of Ext JS from MVC to MVVM
  • The benefits of design patterns in the current version of Ext JS

Discussions about design patterns are often very dry. In this chapter, we'll use some practical examples to illustrate why they're so important and how they can help you kick-start your architecture efforts...

Diary of always

In the beginning, there was a giant mess. Well, maybe not quite, but in modern software development, we've got lots of design and architectural patterns that we can draw on to help us shape an application and ensure we're not reinventing the wheel. Each of these is the result of decades of their work, which is constantly reviewed and put into practice, and we all hope that the most elegant and useful work will bubble to the top. Along the way, we've seen clumsy patterns being overtaken by more elegant ones. Hopefully, our mess has become a little bit less tangled.

A key development in the way we build graphical interfaces was model-view-controller (MVC), which was invented at the near-legendary Xerox PARC in the 1970s by Norwegian computer scientist Trygve Reenskaug. It was first publicly incorporated in Smalltalk, a programming language developed by a cast of computer scientists including Alan Kay. It brought together a host of ideas, which influenced nearly...

Bringing MVC to the Web

Smalltalk's MVC implementation was created with traditional desktop GUI systems in mind. The separation of responsibilities that it represents makes a lot of sense for web-based software; the model is the representation of the business and persistence layers, the controller is the server-side glue, and the view is the HTML rendered for the client browser.

However, in traditional MVC, the view observes changes in the model in order to reflect its current state by responding to events that the model issues. In a standard HTTP request/response situation, this isn't viable.

Model 2 is a derivative of MVC that was implemented in the Java Struts framework, which introduced a potential solution to this issue. Rather than the view and model directly communicating, the controller becomes a marshaling point for changes. It responds to changes in the view and passes them to the model and vice versa, as shown in the following diagram:

Bringing MVC to the Web

MVC/Model 2 on the Web

This is the...

Ext JS and MVC

We've looked at the origins of MVC and the way it was adapted for traditional server-side web applications. How does it work when we use it with the kind of JavaScript-heavy application we'd typically build using Ext JS?

The whole MVC concept moves entirely into the browser. As far as we're concerned, the server can use any technology it wants. It'll generally just provide and consume data to and from the browser. We move back to an MVC implementation that is a little more like the Smalltalk version (different UI elements you see on-screen are views) and each can have their own controller.

Again, this is about breaking down responsibility. Instead of having a single controller take care of an entire page, we can have a search controller, a list controller, and a detail controller (anything that represents the logical units that make up our application). This is a key detail in how the step from server-side MVC to client-side MVC can help our application...

How does it help your application

Let's recap. How are we better off than in Ext JS 3 before we had any of this MVC stuff involved?

  • We've got clear separation of presentation and data with views and models
  • We have a way of orchestrating different parts of our application using controllers
  • We've got a way of splitting our app into logic units by using multiple controllers with associated views

Not only does this lend itself to a good design by keeping different bits of functionality very separate from the outset, but it also gives us a good platform for maintainability purposes because it imposes a very specific way of working.

MVC and the illusion of choice

Given everything we've just covered, you'd think that MVC was the holy grail of development. It's tried and tested, adaptable, and supported by Ext JS. In fact, there are some cases in which it's useful to go a little further and augment MVC.

To use Ext JS-specific examples, let's look at what happens when you start writing a more complicated application. Your controllers can react to the events that your views fire, orchestrate interactions between different views, and even stores other controllers. So, does this mean that you put your event handlers in your controllers, your views, or a combination of both?

This is a key question, which can be answered simply by being very strict with your development process from the beginning. MVC provides the "illusion of choice"; in this, it offers a large variety of ways to set up your application, but only a few that will result in a healthy application.

How about when you have a central...

Diary of always


In the beginning, there was a giant mess. Well, maybe not quite, but in modern software development, we've got lots of design and architectural patterns that we can draw on to help us shape an application and ensure we're not reinventing the wheel. Each of these is the result of decades of their work, which is constantly reviewed and put into practice, and we all hope that the most elegant and useful work will bubble to the top. Along the way, we've seen clumsy patterns being overtaken by more elegant ones. Hopefully, our mess has become a little bit less tangled.

A key development in the way we build graphical interfaces was model-view-controller (MVC), which was invented at the near-legendary Xerox PARC in the 1970s by Norwegian computer scientist Trygve Reenskaug. It was first publicly incorporated in Smalltalk, a programming language developed by a cast of computer scientists including Alan Kay. It brought together a host of ideas, which influenced nearly all the object...

Bringing MVC to the Web


Smalltalk's MVC implementation was created with traditional desktop GUI systems in mind. The separation of responsibilities that it represents makes a lot of sense for web-based software; the model is the representation of the business and persistence layers, the controller is the server-side glue, and the view is the HTML rendered for the client browser.

However, in traditional MVC, the view observes changes in the model in order to reflect its current state by responding to events that the model issues. In a standard HTTP request/response situation, this isn't viable.

Model 2 is a derivative of MVC that was implemented in the Java Struts framework, which introduced a potential solution to this issue. Rather than the view and model directly communicating, the controller becomes a marshaling point for changes. It responds to changes in the view and passes them to the model and vice versa, as shown in the following diagram:

MVC/Model 2 on the Web

This is the way in which...

Ext JS and MVC


We've looked at the origins of MVC and the way it was adapted for traditional server-side web applications. How does it work when we use it with the kind of JavaScript-heavy application we'd typically build using Ext JS?

The whole MVC concept moves entirely into the browser. As far as we're concerned, the server can use any technology it wants. It'll generally just provide and consume data to and from the browser. We move back to an MVC implementation that is a little more like the Smalltalk version (different UI elements you see on-screen are views) and each can have their own controller.

Again, this is about breaking down responsibility. Instead of having a single controller take care of an entire page, we can have a search controller, a list controller, and a detail controller (anything that represents the logical units that make up our application). This is a key detail in how the step from server-side MVC to client-side MVC can help our application architecture.

We already...

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Description

If you are a developer who has knowledge of Ext JS but would like to expand it to encompass the bigger picture of application development, then this book is ideal for you.

Who is this book for?

If you are a developer who has knowledge of Ext JS but would like to expand it to encompass the bigger picture of application development, then this book is ideal for you.

What you will learn

  • Simplify your code by understanding how to use Ext JS view models and data binding
  • Build basic applications with the MVVM architecture
  • Architect advanced Ext JS applications based on a set of requirements
  • Understand code reuse techniques in Ext JS by identifying code that can be extracted to library classes
  • Learn advanced Ext JS topics such as responsive design and sessions in Ext JS
  • Work with testing, debugging, and performance tools to ensure that the final product is robust
  • Discover an integrated approach to building software, in which the design, tools, and code are equally important to a successful final product

Product Details

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Publication date, Length, Edition, Language, ISBN-13
Publication date : Apr 24, 2015
Length: 340 pages
Edition : 1st
Language : English
ISBN-13 : 9781784395308
Vendor :
Netscape
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Product Details

Publication date : Apr 24, 2015
Length: 340 pages
Edition : 1st
Language : English
ISBN-13 : 9781784395308
Vendor :
Netscape
Languages :
Tools :

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Table of Contents

12 Chapters
1. Introduction Chevron down icon Chevron up icon
2. MVC and MVVM Chevron down icon Chevron up icon
3. Application Structure Chevron down icon Chevron up icon
4. Sencha Cmd Chevron down icon Chevron up icon
5. Practical – a CMS Application Chevron down icon Chevron up icon
6. Practical – Monitoring Dashboard Chevron down icon Chevron up icon
7. Practical – an E-mail Client Chevron down icon Chevron up icon
8. Practical – Questionnaire Component Chevron down icon Chevron up icon
9. A Shopping Application Chevron down icon Chevron up icon
10. Debugging and Performance Chevron down icon Chevron up icon
11. Application Testing Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
(1 Ratings)
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4 star 100%
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1 star 0%
DJ K Jun 25, 2015
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
As is mentioned in the forward this book is not for beginners. If you are relatively new to working with Ext JS this book is a good way to become more familiar with concepts like MVC and MVVM. Since the book references Ext JS 5 it is still relevant as of my writing of this review. There are some nice examples of small applications using techniques that can be used in many different apps.
Amazon Verified review Amazon
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