Module1: Introduction

World Wide Web

○ Distributed, collaborative, hypermedia information systems that runs on top of the infrastructure provided by the Internet.

○ “information space in which its resources are identified by global identifiers called Uniform Resource Identifiers / URI” [W3C]

Internet

○ network of networks defined by the TCP/IP standards

○ global system of interconnected computer networks that communicate and interchange data through TCP/IP

○ provides a variety of resources and services such as:

■ WWW documents and applications, email, file sharing, etc.

Tim Berners-Lee

○ invented at European Organization of Nuclear Research (CERN) in 1989

○ developed: HTTP, URL, and HTML

○ founded the World Wide Web Consortium (W3C)

■ one of the leading organizations in the development of technology standards for the web

■ develop protocols and guidelines pertaining to the web

WWW Core Components

○ Web resources

○ Web servers

○ Web clients

○ Uniform Resource Locator (URL)

○ Hypertext Transfer Protocol (HTTP)

Web resources

○ web page

○ scripts, stylesheets, multimedia content

○ may be static or dynamic

web page

HTML document that delivers various information and hyperlinks to other pages and resources

static resource

accessed “as-is“

dynamic resource

generated “on-the-fly“

website

○ related web resources under a common domain name

○ e.g., news website, website of an academic institution

web application

○ website that implements application logic in order to deliver a specific functionality

○ e.g., media streaming service, online banking, online shopping

Web Servers

○ applications that are used to host web resources

○ capable of hosting multiple websites and / or web applications

○ application server: web server that primarily hosts web applications

■ web servers: Apache’s HTTP Server, Microsoft’s IIS

■ application servers: Oracle’s WebLogic, IBM’s WebSphere

Web Clients

○ software applications used to access web resources

○ most common type is the browser

○ also include end-user tools and applications that access web protocols and resources (desktop or mobile)

■ e.g., mobile weather app

Uniform Resource Locator (URL)

unique reference to a web source

Hypertext Transfer Protocol (HTTP)

○ communication protocol between client and server

■ clients send HTTP request messages

■ servers send HTTP response messages

○ payload

■ resource included in the HTTP response by the server such as an image or HTML page

■ data sent by the client to the server for processing such as an input data or uploads

The WWW Now

○ Web Applications

○ Web Platform

○ Web Application Development

Web Applications

○ search engines, banking, e-commerce, e-governance, social networks, entertainment and media streaming, learning management systems, scientific research, website builders, etc.

○ alternative platform for desktop / mobile applications such as productivity tools

○ portable and platform-independent

Web Platform

○ consumption of web APIs and services by non-web applications

○ led to innovative applications and new possibilities for various industries

○ creation of new career opportunities

■ online jobs, content creators, social media managers, influencers, etc.

○ challenges: connectivity, security, scalability

Web application development

○ application logic is divided into those that run on the client-side environment and those that run on the server-side environment

■ front-end developers

■ back-end developers

■ full-stack developers