Chapter 1. Introduction Web Systems and Technologies
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Chapter 1. Introduction
Web Systems and Technologies
Content
1. Introduction
Introduction of web
Evolution of web
Types of Web application
2. Web Application architecture
Web Application components
Web Client side
Web Server side
Introduction to Web Services
3. World Wide Web Consortium (W3C)
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Introduction
The Internet is a vast, international network, made up ofcomputers and the physical connections (wires, routers, etc.)allowing them to communicate.
It is the largest network in the world that connects hundreds ofthousands of individual networks all over the world.
The popular term for the Internet is the “information highway”.
Rather than moving through geographical space, it moves yourideas and information through cyberspace – the space ofelectronic movement of ideas and information.
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How to access the Internet?
Many schools and businesses have direct access to the Internetusing special high-speed communication lines and equipment.Students and employees can access through the organization’slocal area networks (LAN) or through their own personalcomputers.
Another way to access the Internet is through Internet ServiceProvider (ISP).
To access the Internet, an existing network need to pay a smallregistration fee and agree to certain standards based on theTCP/IP (Transmission Control Protocol/Internet Protocol) referencemodel.
Internet Service Provider (ISP)
A commercial organization with permanent connection to theInternet that sells temporary connections to subscribers.
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What is Web? The World Wide Web (WWW or just the Web) is a collection of software
that spans the Internet and enables the interlinking of documents andresources.
The Web consists of information organized into Web pages containingtext and graphic images.
It contains hypertext links, or highlighted keywords and images that leadto related information.
Links: A connection between one web page and another.
A collection of linked Web pages that has a common theme or focus iscalled a Web site.
The main page that all of the pages on a particular Web site areorganized around and link back to is called the site’s home page.
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Evolution of Web
The growth of computing expanded in multiple.
Organizations connect together to share data.
This makes the beginning of computer networks.
Web and Internet
WANs raised a strong need about globaldata sharing
This resulted referred as WWW.
Internet is known as the largest WAN.
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Web can be classified
Web 1.0
To be Known as traditional Web.
Authors write/publish content on the Web.
The published content has read-only format.
Posing the problem of User interactivity.
7Web Author
Internet
Web Reader
readwrite
Web can be classified (2)
Web 2.0
Web 2.0 also called as the read-write web.
Readers can interact the authors by providing comments, blogs,queries, rating and so on.
It’s great platform for the readers to share their viewpoints with theauthors.
The Web space is limited in Web 1.0 and 2.0.
8Web Author
Internet
Web Reader
read/write read/write
Web can be classified (3)
Semantic web
Concept to be expected as the future of web.
It is the read-write-request web.
The user can send the request for Web space.
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Web Author
Web
Web Reader
read/write/request
SemanticWeb space
SemanticWeb space
read/write/request
How to access the Web?
Once you have your Internet connection, then you need specialsoftware called a browser to access the Web.
Web browsers are used to connect you to remote computers,open and transfer files, display text and images.
Web browsers are specialized programs.
Examples of Web browser: Netscape Navigator (Navigator) andInternet Explorer, Chrome, Safari, FireFox.
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Static/Dynamic Web pages
Static Web page
Static Web pages have a limitations.
Difficult to maintain, Updated manually, Inconsistency.
Don’t allow any user interaction.
Dynamic Web page
Include static as well as dynamic web pages.
Allows customizing the content and its appearance in thebrowser.
Geneates content “on-demand”.
Accepts the user inputs through web browser.
Serveral technologies envoled to make web sites more flexibleand dynamic.
Variety device such as PDAs, Cell phones, and so on is used XHTMLDocuments 11
Addresses on the Web: IP Addressing
Each computer on the internet does have a unique identificationnumber, called an IP (Internet Protocol) address.
The IP addressing system currently in use on the Internet uses afour-part number.
Each part of the address is a number ranging from 0 to 255, andeach part is separated from the previous part by period,
For example, 106.29.242.17, 192.168.0.1
The combination of the four IP address parts provides 4.2 billionpossible addresses (256 x 256 x 256 x 256).
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Domain Name Addressing
Most web browsers do not use the IP address t locate Web sitesand individual pages.
They use domain name addressing.
A domain name is a unique name associated with a specific IPaddress by a program that runs on an Internet host computer.
This program, which coordinates the IP addresses and domainnames for all computers attached to it, is called DNS (DomainName System ) software.
The host computer that runs this software is called a domain nameserver.
No other computer on the Internet has the same domain name.
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Uniform Resource Locators
The IP address and the domain name each identify a particularcomputer on the Internet.
However, they do not indicate where a Web page’s HTMLdocument resides on that computer.
To identify a Web pages exact location, Web browsers rely onUniform Resource Locator (URL).
URL is a four-part addressing scheme that tells the Web browser:
What transfer protocol to use for transporting the file
The domain name of the computer on which the file resides
The pathname of the folder or directory on the computer onwhich the file resides
The name of the file
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Structure of a Uniform Resource Locators
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http://www.chicagosymphony.org/civicconcerts/index.htm
protocol
Domain name
pathname
filename
http => Hypertext Transfer Protocol
Hypertext Transfer Protocol (HTTP)
The transfer protocol is the set of rules that the computers use tomove files from one computer to another on the Internet.
The most common transfer protocol used on the Internet is theHypertext Transfer Protocol (HTTP).
Two other protocols that you can use on the Internet are the FileTransfer Protocol (FTP) and the Telnet Protocol
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Types of Web Application
Static Web Application
Dynamic Web Application
Shop online or e-commerce
Portal Web Application
Animation Web Application
Web Application with CMS
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Client/Server Structure of the Web
Web is a collection of files that reside on computers, called Webservers, that are located all over the world and are connected toeach other through the Internet.
When you use your Internet connection to become part of theWeb, your computer becomes a Web client in a worldwideclient/server network.
A Web browser is the software that you run on your computer tomake it work as a web client.
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Web Application architecture
WWW use classical client / server architecture
HTTP is text-based request-response protocol
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Page request
Client running a Web Browser
Server running Web Server Software (IIS,
Apache, etc.)
Server response
HTTP
HTTP
Server-Side Code
Languages/frameworks include but are not limited to Ruby (Rails),Javascript (Node.js), Python (Django), PHP, C#, and Java; but thelist of possibilities is infinite. Any code that can run on a computerand respond to HTTP requests can run a server.
Stores persistent data (user profiles, instatweets, mybook pages,etc.).
Cannot be seen by the user (unless something is terribly wrong).
Can only respond to HTTP requests for a particular URL, not anykind of user input.
Creates the page that the user finally sees (this is generally onlytrue in web applications that choose to render most of theirlayouts on the server)
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Client-Side Code
Languages used include: HTML, CSS, and JavaScript.
Parsed by the user’s browser.
Reacts to user input.
Can be seen and edited by the user in full.
Cannot store anything that lasts beyond a page refresh.
Cannot read files off of a server directly, must communicate viaHTTP requests.
Creates the page that the user finally sees (this is generally onlytrue in single page applications).
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Introduction to Web Services
A Web service is a software module that has a URL or an Internetaddress so they can be called upon to perform a operation viathe Internet.
One Web service makes a request of another Web service toperform its task or tasks and pass back an answer creating a highlydistributed system.
Using XML based messages via internet-based protocols.
Web Services are latest distributed technology
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Introduction to Web Services (2)
Benefits of Web Services:
Loosely Coupled: Each service exists independently of the otherservices that make up the application. Individual pieces of theapplication to be modified without impacting unrelated areas.
Ease of Integration: Data is isolated between applicationscreating ’silos’. Web Services act as glue between these andenable easier communications within and across organisations.
Service Reuse: Takes code reuse a step further. A specificfunction within the domain is only ever coded once and usedover and over again by consuming applications.
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Web Services Architectures
The simplest Web service system has two participants:
A service producer (provider)
A service consumer(requester).
The provider presents the interface and implementation of theservice, and the requester uses the Web service.
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Web Services Architectures (2)
The simplest Web service system has two participants:
A service producer (provider)
A service consumer(requester).
The provider presents the interface and implementation of theservice, and the requester uses the Web service.
Service-Oriented Architecture
A broker, acts as a broker for Web services.
A provider, can publish services to the registry
A consumer, can then discover services in the registry
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Web Services Architectures (3)
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Service Provider
Service Requestor
Service BrokerService
Registry(UDDI)
Publish Bind/ Communicati
on
Find/Look up
World Wide Web Consortium (W3C)
Founded in 1994 by Tim Berners-Lee
Devoted to developing non-proprietary and interoperabletechnologies for the World Wide Web and making the Webuniversally accessible
Standardization
W3C Recommendations: technologies standardized by W3C
include Extensible Hyper Text Markup Language (XHTML),Cascading Style Sheets (CSS) and the Extensible MarkupLanguage (XML)
Document must pass through Working Draft, CandidateRecommendation and Proposed Recommendation phasesbefore considered for W3C Recommendation
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XML – eXtensible Markup Language
Extensible Markup Language (XML) is a markup language thatdefines a set of rules for encoding documents in a format that isboth human-readable and machine-readable.
The design goals of XML emphasize simplicity, generality, andusability over the Internet.
Many application programming interfaces (APIs) have beendeveloped to aid software developers with processing XML data,and several schema systems exist to aid in the definition of XML-based languages.
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SOAP - Simple Object Access Protocol
Is an text-based standard protocol of WS.
Enables communication between Web services and Web serviceclients.
Allows different enterprises to communicate and exchangeinformation as SOAP messages
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