The World Wide Web. Web Growth Web Server Statistics Apache is the most popular web server today (freely available) Microsoft IIS is gaining ground.

Slides:



Advertisements
Similar presentations
DT228/3 Web Development WWW and Client server model.
Advertisements

 To publish information for global distribution, one needs a universally understood language, a kind of publishing mother tongue that all computers may.
Kyung Hee University 1 1 Application Layer. 2 Kyung Hee University Position of Application Layer.
© 2010, Robert K. Moniot Chapter 1 Introduction to Computers and the Internet 1.
HTTP: the hypertext transfer protocol
TCP/IP summary Skills: none IT concepts: review This work is licensed under a Creative Commons Attribution-Noncommercial- Share Alike 3.0 License.
The Web The World Wide Web What does it do?.
How the web works: HTTP and CGI explained
World Wide Web1 Applications World Wide Web. 2 Introduction What is hypertext model? Use of hypertext in World Wide Web (WWW) – HTML. WWW client-server.
The World Wide Web and the Internet Dr Jim Briggs 1WUCM1.
Definitions, Definitions, Definitions Lead to Understanding.
© 2004, Robert K. Moniot Chapter 1 Introduction to Computers and the Internet.
Implementing Application Protocols. Overview An application protocol facilitates communication between applications. For example, an client uses.
CMPT Web Programming Introduction and Basic HTML.
INTRODUCTION TO WEB DATABASE PROGRAMMING
CS 299 – Web Programming and Design CS299: Web Programming and Design Instructor: Dr. Fang (Daisy) Tang.
The WWW and HTML CMPT 281. Outline Hypertext The Internet The World-Wide-Web How the WWW works Web pages Markup HTML.
FALL 2005CSI 4118 – UNIVERSITY OF OTTAWA1 Part 4 Web technologies: HTTP, CGI, PHP,Java applets)
HTTP; The World Wide Web Protocol
Copyright © cs-tutorial.com. Introduction to Web Development In 1990 and 1991,Tim Berners-Lee created the World Wide Web at the European Laboratory for.
Chapter 1: Introduction to Web
Chapter 16 The World Wide Web Chapter Goals Compare and contrast the Internet and the World Wide Web Describe general Web processing Describe several.
INFORMATION TECHNOLOGY IN BUSINESS AND SOCIETY SESSION 7 – THE WEB SEAN J. TAYLOR.
2013Dr. Ali Rodan 1 Handout 1 Fundamentals of the Internet.
HyperText Transfer Protocol (HTTP).  HTTP is the protocol that supports communication between web browsers and web servers.  A “Web Server” is a HTTP.
CP476 Internet Computing Lecture 5 : HTTP, WWW and URL 1 Lecture 5. WWW, HTTP and URL Objective: to review the concepts of WWW to understand how HTTP works.
Programming the Web Web = Computer Network + Hypertext.
CIS 1310 – HTML & CSS 1 Introduction to the Internet.
MySQL and PHP Internet and WWW. Computer Basics A Single Computer.
Kingdom of Saudi Arabia Ministry of Higher Education Al-Imam Muhammad Ibn Saud Islamic University College of Computer and Information Sciences Chapter.
Internet Protocol B Bhupendra Ratha, Lecturer School of Library and Information Science Devi Ahilya University, Indore
CS 6401 The World Wide Web Outline Background Structure Protocols.
Web Design (1) Terminology. Coding ‘languages’ (1) HTML - Hypertext Markup Language - describes the content of a web page CSS - Cascading Style Sheets.
Overview Web Session 3 Matakuliah: Web Database Tahun: 2008.
INTRODUCTION TO WEB APPLICATION Chapter 1. In this chapter, you will learn about:  The evolution of the Internet  The beginning of the World Wide Web,
World Wide Web “WWW”, "Web" or "W3". World Wide Web “WWW”, "Web" or "W3"
WWW: an Internet application Bill Chu. © Bei-Tseng Chu Aug 2000 WWW Web and HTTP WWW web is an interconnected information servers each server maintains.
Chapter 29 World Wide Web & Browsing World Wide Web (WWW) is a distributed hypermedia (hypertext & graphics) on-line repository of information that users.
1 WWW. 2 World Wide Web Major application protocol used on the Internet Simple interface Two concepts –Point –Click.
INTERNET PROTOCOLS. Microsoft’s Internet Information Server Home Page Figure IT2031 UNIT-3.
IS-907 Java EE World Wide Web - Overview. World Wide Web - History Tim Berners-Lee, CERN, 1990 Enable researchers to share information: Remote Access.
Copyright © 2008 Pearson Education, Inc. Publishing as Pearson Addison-Wesley Chapter 1 Fundamentals.
Web Technologies Lecture 1 The Internet and HTTP.
Web Server.
Web Services. 2 Internet Collection of physically interconnected computers. Messages decomposed into packets. Packets transmitted from source to destination.
27.1 Chapter 27 WWW and HTTP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Internet Applications (Cont’d) Basic Internet Applications – World Wide Web (WWW) Browser Architecture Static Documents Dynamic Documents Active Documents.
EE 122: Lecture 21 (HyperText Transfer Protocol - HTTP) Ion Stoica Nov 20, 2001 (*)
CS 6401 The World Wide Web Outline Background Structure Protocols.
Fundamentals. A Brief Intro to the Internet - Origins - ARPAnet - late 1960s - Network reliability - For ARPA-funded research organizations - BITnet,
ASP-2-1 SERVER AND CLIENT SIDE SCRITPING Colorado Technical University IT420 Tim Peterson.
JavaScript and Ajax (Internet Background) Week 1 Web site:
Matthew Baillie, Luke Day THE INTERNET. HISTORY OF THE INTERNET J.C.R. Licklider authored a series of memos concerning theoretical network structures.
Web Design Terminology Unit 2 STEM. 1. Accessibility – a web page or site that address the users limitations or disabilities 2. Active server page (ASP)
The Internet Salihu Ibrahim Dasuki (PhD) CSC102 INTRODUCTION TO COMPUTER SCIENCE.
1 Chapter 1 INTRODUCTION TO WEB. 2 Objectives In this chapter, you will: Become familiar with the architecture of the World Wide Web Learn about communication.
Web Development. Agenda Web History Network Architecture Types of Server The languages of the web Protocols API 2.
Tonga Institute of Higher Education IT 141: Information Systems
WWW and HTTP King Fahd University of Petroleum & Minerals
CISC103 Web Development Basics: Web site:
JavaScript and Ajax (Internet Background)
HTTP: the hypertext transfer protocol
Tutorial (4): HTTP Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
CISC103 Web Development Basics: Web site:
1 Introduction to the Internet.
Chapter 27 WWW and HTTP.
Tonga Institute of Higher Education IT 141: Information Systems
Tonga Institute of Higher Education IT 141: Information Systems
EE 122: HyperText Transfer Protocol (HTTP)
Introduction to World Wide Web
Presentation transcript:

The World Wide Web

Web Growth

Web Server Statistics Apache is the most popular web server today (freely available) Microsoft IIS is gaining ground

The World Wide Web: A Brief History

Vannevar Bush 1945

MEMory EXtender system Problem: –Bush was concerned about “new knowledge not reaching the people who would benefit from it”

MEMory EXtender system Store publications, correspondence, and personal work on microfilm Items retrieved rapidly using index codes Can annotate text with margin notes, comments Can construct a trail through the material and save it Acts as an external memory

MEMory EXtender system limitations Basic unit of content is an image page –No links to/from sub-text No digital content –No keyword search, only TOC/index codes No networking –No rapid info sharing

Results The MEMory EXtender system was the inspiration for the creators of hypertext and the web

Marshall McLuhan 1964 – Hypertext Coined McLuhan is known for coining the expressions the medium is the message and the global village, and for predicting the World Wide Web almost thirty years before it was invented

Tim Berners-Lee invents Global Hypertext WWW 1991 Sir Timothy John "Tim" Berners-Lee is an English computer scientist known as the inventor of the World Wide Web. He made a proposal for an information management system in March 1989, and on 25 December 1990, with the help of Robert Cailliau and a young student at CERN, he implemented the first successful communication between a Hypertext Transfer Protocol (HTTP) client and server via the Internet. By the mid 1990s, the World Wide Web had replaced Mark P. McCahill's Gopher protocol as the dominant Internet protocol. Berners-Lee is the director of the World Wide Web Consortium (W3C), which oversees the Web's continued development. He is also the founder of the World Wide Web Foundation, and is a senior researcher and holder of the Founders Chair at the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL). He is a director of the Web Science Research Initiative (WSRI),and a member of the advisory board of the MIT Center for Collective Intelligence.

World First Browser and Web page. 3

Then… 4

What has happened through the years? Appearance of JavaScript (JS) in Late Standardization of HTML in Jan Introduction of Cascading Style Sheet (CSS) in Document Object Model (DOM) was standardized in End of Begin to be working in AJAX (Widely used by Google in 2004). 5

Web Architecture 6

The World Wide Web: HTTP Protocol

Both were invented at the same time by the same person HTTP vs HTML HTML: hypertext markup language –Definitions of tags that are added to Web documents to control their appearance HTTP: hypertext transfer protocol –The rules governing the conversation between a Web client and a Web server

What is a protocol? In diplomatic circles, a protocol is the set of rules governing a conversation between people We have seen that the client and server carry on a machine-to-machine conversation A network protocol is the set of rules governing a conversation between a client and a server There are many protocols, HTTP is just one

I would like to open a connection GET Display response Close connection OK Send page or error message OK Client Server HTTP is the set of rules governing the format and content of the conversation between a Web client and server An HTTP conversation

An HTTP example The message requesting a Web page must begin with the work “GET” and be followed by a space and the location of a file on the server, like this: GET /fac/lpress/shortbio.htm The protocol spells out the exact message format, so any Web client can retrieve pages from any Web server.

Network protocols The details are only important to developers. The rules are defined by the inventor of the protocol – may be a group or a single person. The rules must be precise and complete so programmers can write programs that work with other programs. The rules are often published as an RFC along with running client and server programs.RFC The HTTP protocol used for Web applications was invented by Tim Berners Lee.Tim Berners Lee RFC = request for comments

Tim Berners-Lee Tim Berners-Lee was knighted by Queen Elizabeth for his invention of the World Wide Web. He is shown here, along with the first picture posted on the Web and a screen shot from an early version of his Web browser.

HTTP is an application layer protocol The Web client and the Web server are application programs Application layer programs do useful work like retrieving Web pages, sending and receiving or transferring files Lower layers take care of the communication details The client and server send messages and data without knowing anything about the communication network

The application layer is boss – the top layer Your boss says: Send this package to Miami -- I don't care if you use Federal Express, UPS, or any other means. Also, let me know when it arrives or if it cannot be delivered for some reason. The application program says: Send this request to the server -- I don't care how you do it or whether it goes over phone lines, radio, or anything else about the details. Just send the message, and let me know when it arrives or if it cannot be delivered for some reason. LayerFunction ApplicationDo useful work like Web browsing, , and file transfer Lower layersHandle communication between the client and server There are five TCP/IP layers, the application layer and four lower layers.

Many application layer protocols are used on the Internet, HTTP is only one ProtocolApplication HTTP: Hypertext TransferRetrieve and view Web pages FTP: File Transfer Copy files from client to server or from server to client SMTP: Simple Mail Transport Send POP: Post OfficeRead

The TCP/IP protocol layers Application Transport Internet Data link Physical Get useful work done – retrieve Web pages, copy files, send and receive , etc. Make client-server connections and optionally control transmission speed, check for errors, etc. Route packets between networks Route data packets within the local area network Specify what medium connects two nodes, how binary ones and zeros are differentiated, etc, The application program is king – it gets work done using the lower level layers for communication between the client and server.

HTTP Operations GET: retrieves URL (most widely used) HEAD: retrieves only response header POST: posts data to server PUT: puts page on server DELETE: deletes page from server

Simple HTTP Request and Reply Request: GET HTTP/1.0 Response: HTTP-Version: HTTP/ OK Content-Length: 3012 Content-Type: text/html

HTTP 1.0 Client opens a separate TCP connection for each requested object Object is served and connection is closed Advantages –maximum concurrency Limitations –TCP connection setup/tear-down overhead –TCP slow start overhead

HTTP 1.0 Client Server ACK, GET Retrieve Data From Disk Retrieve Image From Disk SYN SYN, ACK connect() close() connect() ACK, GET image.gif SYN SYN, ACK close() write()

HTTP 1.1 Client Server ACK, GET Retrieve Data From Disk Retrieve Image From Disk SYN SYN, ACK connect() GET image.gif close() write()

Server Side Close() Client Server ACK, GET Retrieve Data From Disk Retrieve Image From Disk SYN SYN, ACK connect() GET image.gif write() Timeout! close() Set timeout Reset timeout

Dynamic Content Web pages can be created as requests arrive Advantages –Personalization (e.g., my.yahoo.com), –interaction with client input –interaction with back-end applications Disadvantages –Performance penalty Generating dynamic content (CGI, ASP, PHP, ColdFusion, JavaScript, Flash, …)

CGI Scripts CGI scripts are URLs with a.cgi extension The script is a program (e.g., C, JAVA, …) When the URL is requested, server invokes the named script, passing to it client info Script outputs HTML page to standard output (redirected to server) Server sends page to client

CGI Execution Server CGI Script fork() Send page Request Response

Active Server Pages (ASPs) Active server pages are HTML documents with extensions for embedded program execution When request arrives, server fetches and parses the HTML document Server executes embedded executable code and plugs output into page Expanded page is sent to client