Web Application Frameworks - Web Technologies (1019888BNR)

2 December 2005
Web Technologies
Web Application Frameworks
Prof. Beat Signer
Department of Computer Science
Vrije Universiteit Brussel
http://www.beatsigner.com

Beat Signer - Department of Computer Science - bsigner@vub.ac.be 2October 21, 2016
Web Application Frameworks
 There exist dozens of web application frameworks!
A web application framework is a software framework that
is designed to support the development of dynamic web-
sites, web applications, web services and web resources.
The framework aims to alleviate the overhead associated
with common activities performed in web development.
For example, many frameworks provide libraries for
database access, templating frameworks and session
management, and they often promote code reuse.
[http://en.wikipedia.org/wiki/Web_application_framework]

Web Application Frameworks ...
 A web application framework offers libraries and
tools to deal with web application issues
 template libraries, session management, database access
libraries etc.
 Some frameworks also offer an abstraction from the
underlying enabling technologies
 e.g. automatic creation of Java Servlets
 Many frameworks follow the Model-View-Controller (MVC)
design pattern
 no mix of application logic and view (e.g. not like in JSP)
 increases modularity and reusability
 Lead to a faster and more robust development process

Model-View-Controller (MVC)
 Model
 data (state) and business logic
 multiple views can be defined for a single model
 when the state of a model changes, its views are notified
 View
 renders the data of the model
 notifies the controller about changes
 Controller
 processes interactions with the view
 transforms view interactions into
operations on the model (state
modification)
Model
Controller
View
notifies
modifies
state
selects view
notifies
gets
state

All-Inclusive MVC Frameworks
 Java
 Apache Struts 2
 Spring
 PHP
 Yii
 Zend
 CakePHP
 Ruby
 Ruby on Rails
 Python
 Django
 JavaScript
 Node.js + Express.js
 .NET (C#, Visual Basic)
 ASP.NET MVC

Apache Struts 2
 Free open source framework for creating enterprise-
ready Java-based web applications
 Action-based MVC Model 2 (Pull MVC) framework
combining Java Servlets and JSP technology
 model
- action (basic building blocks) from which the view can pull information via the
ValueStack
- action represented by POJO (Plain Old Java Object) following the JavaBean
paradigm and optional helper classes
 view
- template-based approach often based on JavaServer Pages (JSP) in
combination with tag libraries (collection of custom tags)
 controller
- based on Java Servlet filter in combination with interceptors

MVC Model 2 (MVC 2) in Struts 2
Model
POJOs
Database
Controller
Servlet
View
e.g. JSP
Browser
1
2
3
4
5
6

Apache Struts 2 Architecture
 Receive request
 filter chain
- interception of requests and
responses, e.g. XSLT
transformation
 Execute relevant Action
 invoke interceptors
 read/update data (model)
 Build response (view)
 often based on JSP template
 interceptors in reverse order
 Send response
 again through filter chain
[http://struts.apache.org/2.1.6/docs/big-picture.html]

DEMO: Struts 2 Form Validation

Spring Framework
 Java application framework
 Various extensions for web applications
 Modules
 model-view-controller
 data access
 inversion of control container
 convention-over-configuration
 remote access framework
 transaction management
 authentication and authorisation
 …

Yii Framework
 PHP framework for the development of Web 2.0
applications that offers a rich set of features
 AJAX-enabled widgets
 web service integration
 authentication and authorisation
 flexible presentation via skins and themes
 Data Access Objects (DAO) interface to transparently access
different database management systems
 integration with the jQuery JavaScript library
 layered caching
 ...

Zend
 Open source PHP framework offering various features
 MVC architectural pattern
 loosely coupled components
 object orientation
 flexible caching
 Simple Cloud API
 features to deal with emails (POP3, IMAP4, …)
 …

CakePHP
 Open source PHP web application framework
 rapid prototyping via scaffolding
 authentication
 localisation
 session management
 caching
 validation
 …

DEMO: CakePHP

Ruby on Rails (RoR)
 Open source web application framework
 Combination of
 dynamic, reflective, object-oriented programming language Ruby
- combination of Perl-inspired syntax with "Smalltalk features"
 web application framework Rails
 Based on MVC architectural pattern
 structure of a webpage separated from its functionality via the
unobtrusive JavaScript technique
 The scaffolding feature offered by Rails can
automatically generate some of the models and views
that are required for a website
 developer has to run an external command to generate the code

Ruby on Rails (RoR) ...
 Ruby on Rails Philosophy
 Don't Repeat Yourself (DRY)
- information should not be stored redundantly (e.g. do not store information in
configuration files if the data can be automatically derived by the system)
 Convention over Configuration (CoC)
- programmer only has to specify unconventional application settings
- naming conventions to automatically map classes to database tables (e.g. by
default a 'Sale' model class is mapped to the 'sales' database table)
 High modularity
 plug-ins can be added for desired server-side functionality
 use RubyGems package manager to easily add plug-ins (“gems”)

DEMO: Ruby on Rails

Django
 Open source Python web application framework
 don't repeat yourself (DRY)
 object-relational mapper
- mapping between model (Python classes) and a relational database
 integrated lightweight web server
 localisation
 caching
 ...

Node.js
 Server-side JavaScript
 low-level, comparable to functionality offered by Servlets
 handling post/get requests, database, sessions, …
 Write your entire app in one language
 however, server-side and client-side code still separated
 Built-in web server (no need for Apache, Tomcat, etc.)
 High modularity
 packages can be added for additional functionality (via npm)
 Other more powerful frameworks such as Express.js build
on top of Node.js
 HTTP utility methods (routing, sessions, ...)
 template engines (Jade or EJS)

ASP.NET MVC
 Web framework for .NET languages (C#, VB)
 inversion of control container
 extensible and pluggable framework
- can use any existing .NET libraries in the form of DLL files
- core components such as view engine or URL routing modules can be
replaced
 can generate some of the client-side JavaScript for you
- form validation
- dynamic updates using Ajax
 localisation
 session management
 caching
 …

Specialised Frameworks and Toolkits
 Client-side web frameworks
 Backbone.js
 Ember.js
 Angular.js
 Creating browser-based RIAs
 Microsoft Silverlight
 Creating cross-platform RIAs
 Apache Flex
 Creating desktop applications
 NW.js
 Electron

Backbone.js
 Cleanly separate data (Model) and user interface (View)
 you provide server-side interface to read/write models
 Backbone.js does the rest on the client side
 Model
 load and save models from server
 emit events when data changes
 View
 display models, capture user input and interactions
 listens for changes and update view if needed

Ember.js
 Client-side MVC
 Built for single-page web applications
 information is refreshed dynamically on demand
 no page refreshes required
 Comes with Ember Data, a data persistence library
 provides facilities for object-relational mapping (ORM)
 maps client-side models to server-side data
 usage is optional, you can also provide your own interface to the
server-side data
 Users can create custom HTML tags ("components")
 can also include logic relevant to the new tag’s function
- e.g. handle user input or deal with child elements placed in between the
custom tags

Angular.js
 Client-side "MVC"
 Two-way data binding between models and views
 Plain HTML as templates
 HTML is extended (e.g. via attributes) to map models to the
template, remains valid HTML
 Users can create custom HTML tags ("directives")
 can also include logic relevant to the new tag’s function
<div ng-controller="AlbumCtrl">
<ul>
<li ng-repeat="image in images">
<img ng-src="{{image.thumbnail}}" alt="{{image.description}}">
</li>
</ul>
</div>

Microsoft Silverlight
 Microsoft's platform for Rich Internet Applications
 competitor to Adobe Flash
 Runtime requires a browser plug-in
 Internet Explorer, Firefox, Safari and Google Chrome
 Silverlight Core Common Language Runtime (CoreCLR)
 A Silverlight application consists of
 CreateSilverlight.js and Silverlight.js
- initialise the browser plug-in
 user interface described in the Extensible Application Markup
Language (XAML)
- XAML files are not compiled  indexable by search engines
 code-behind file containing the program logic

Microsoft Silverlight ...
 Programming based on a subset of the .NET Framework
 Silverlight introduces a set of features including
 LocalConnection API
- asynchronous messaging between multiple applications on the same machine
 out-of-browser experiences
- locally installed application that runs out-of-the-browser (OOB apps)
- cross-platform with Windows/Mac
 microphone and Web cam support

Apache Flex
 Software development kit for cross-platform
Rich Internet Applications (RIAs) based on Adobe Flash
 Main components
 Adobe Flash Player runtime environment
 Flex SDK (free)
- compiler and debugger, the Flex framework and user interface components
 Adobe Flash Builder (commercial)
- Eclipse plug-in with MXML compiler and debugger
 Separation of user interface and data
 user interface described in MXML markup language in
combination with ActionScript
- compiled into flash executable (SWF flash movie)

Apache Flex ...
 Flex applications can also be deployed as mobile and
desktop applications via Adobe AIR (Adobe Integrated
Runtime)
<?xml version="1.0" encoding="UTF-8" ?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="horizontal">
<mx:Script>
<![CDATA[
import mx.controls.Alert;
private function sayHello():void {
Alert.show("Hello " + user.text);
}
]]>
</mx:Script>
<mx:Label fontSize="12" text="Name: " />
<mx:TextInput id="user" />
<mx:Button label="Go" click="sayHello()" />
</mx:Application>
HelloWorld.mxml

NW.js
 Formerly node-webkit project
 Bundles your app for usage as desktop application
 Webkit + Node.js + Application Files (HTML, JS, CSS, …)
 Lets you call Node.js modules directly from DOM
 e.g. use filesystem module to read and write files
 Included API provides access to native UI features
 right-click context menu
 system tray icon
 notifications
 …

DEMO: NW.js

Electron
 Similar to NW.js
 Developed for GitHub's Atom editor, now widely used

Web Content Management Systems
 Content management systems that focus on web content
 Main functionality
 data storage and publishing, user management (including access
rights), versioning, workflows
 Offline (create static webpages), online (create
webpages on the fly) and hybrid systems
 Graphical interface for creating and managing content
 Suited for non-technical users since the underlying
technology is normally completely hidden
 Web CMS Examples
 Joomla, Drupal, Wordpress, ...

Exercise 4
 Java Servlets and Modern Web Application
Frameworks

References
 Struts 2 Quick Guide
 http://www.tutorialspoint.com/struts_2/struts_quick_guide.htm
 Apache Struts 2
 http://struts.apache.org
 Ian Roughley, Struts 2
 http://refcardz.dzone.com/refcardz/struts2
 Spring Framework
 http://www.springsource.org
 Yii Framework
 http://www.yiiframework.com

References ...
 Zend Framework
 http://framework.zend.com
 CakePHP
 http://cakephp.org
 Ruby on Rails
 http://rubyonrails.org
 Django
 https://www.djangoproject.com
 Node.js
 http://nodejs.org
 http://expressjs.com

References ...
 ASP.NET MVC
 http://www.asp.net/mvc
 Backbone.js
 http://backbonejs.org
 Ember.js
 http://emberjs.com
 Angular.js
 https://angularjs.org
 Microsoft Silverlight
 http://www.microsoft.com/silverlight/
 http://silverlight.net/learn/videos/silverlight-videos/net-ria-services-intro/

References ...
 Apache Flex
 http://flex.apache.org
 NW.js
 http://nwjs.io
 Electron
 http://electron.atom.io
 Comparision of Web Application Frameworks
 http://en.wikipedia.org/wiki/Comparison_of_web_
application_frameworks

2 December 2005
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