Introducing The Internet

The Internet has created a revolution in the way in which people and businesses communicate. The World Wide Web is the most important application of Internet technologies and no business can ignore the opportunities that it offers. In the late 1990s these opportunities seemed endless and led eventually to the ‘dot com’ boom and to the eventual bust. Despite this speculative bubble, the underlying business benefits of the web are still just as strong, and we are now in a better position to be able to separate unrealistic dreams from good business applications.The Internet• Created a revolution in communication• WWW - most important Internet technology** No business can ignore the opportunities it offers** led to ‘dot com’ boom of the 90s, and its eventual bust (business benefits of the web are still as strong)Internet History>> The Internet developed from work done in the 60s/70s by the US Department of Defence on the ARPAnet (Advanced Research Projects Agency net) project** connecting computers in a network** networks assumed to be unreliable** resilience was a critical objectiveInternet Theory• A collection of networks• Any computer can talk to any other• No single computer in control• ScalabilityNote:** an internet is an idea - a collection of networks** the Internet is the implementation of the ideaCommunications Networks• Circuit switched (used by the telephone system)** complete circuit from sender to receiver** connections need to be maintained for duration of conversation** not always the most efficient way of transmitting data between networks• Packet switched (the Internet uses this approach)** Message broken into chunks (packets)** Each packet may take a different route** Packets can arrive out of sequence** Users share communication links** Efficient utilization of communication infrastructureInternet Protocol (IP) Addresses• Computers that connect to the Internet are known as hosts• Each host has a unique address (IP address)** a.b.c.d (numbers between 0 and 255)** e.g. Google.com : 64.233.187.99• Four numbers separated by dots – hence known as the ‘dotted quad’Internet Protocols• The Internet is based on well-defined rules - protocols• Ensure that computers can communicate• Fundamental to Internet success• Many communication protocols are created by national and international standards organizations, and documented• Internet protocols are defined through Request For Comment (RFC) documentsRequest For Comment• Less formal than international standards• Not all RFCs become standards• Well defined standardization process** proposed standard** draft standardInternet standard• Each RFC has a unique serial number (RFC 2026 describes the process)• Publicly available, free of chargeInternet Protocol• Rules for transferring packets• Dependent on IP addresses• Does not guarantee reliable delivery**packets could be delivered out of sequence, with unpredictable timing, not delivered at allTransmission Control Protocol• Operates on top of IP to produce reliable delivery** breaks data into packet-sized chunks** checks for corrupt packets** checks for missing packets** requests replacement packets** re-assembles packets into a message at destinationUser Datagram Protocol• UDP simpler/faster• All message data in one packet• No replacement packets• Useful for simple applications onlyDomain Name System (DNS)• Each host given a textual name in place of numerical IP address• Words separated by dots• DNS translates these to the corresponding numerical addressInternet Administration and Funding• No-one owns the Internet** a vast number of networks, communications infrastructure and other equipment• Some funded directly or indirectly by governments• Other parts of the infrastructure is owned by commercial organizations such as telecommunications companies** charge for providing a connection to the Internet• End users (individual home users or businesses) gain access to this network in a variety of different ways** different types of chargesTypes of Charges• Pay as you go** user pays the usual telephone charges for making a connection to the ISP - no other fees** ISP receives a small proportion of the call charge from the telecommunications operator• Monthly subscription by user to the ISP** user does not pay for the telephone calls, or alternatively a low fixed rate - more economical for regular Internet end-users• A fixed fee is paid periodically to an ISP for an ‘always on service’** typical for small businesses• Often, ISPs provide additional services such as a technical support, email, special content etc.The Internet and the Law• The Internet is not outside the law• Because of rapid Internet growth, national legislation lags• Import and export regulations• Intellectual Property Rights• Damaging statements• Network etiquette• Activities that are unlawful via some other media - usually unlawful if accomplished over the InternetInternet Applications• Applications use Internet protocols• Designed for user interaction• Quality and usefulness of applications account for the success of the Internet• Most important applications are:** electronic mail (email)** file transfer protocol (ftp)** remote login (telnet)** newsgroups (nntp)** World Wide Web (WWW)** instant messaging and Internet Relay Chat (IRC)Electronic Mail• One of the most heavily used Internet tools• Uses store-and-forward approachEmail Addresses• Email relies on the use of addresses• Address is made up of two parts** Domain name, e.g. google.com• The user name, such as joe** (user_name)@(domain_name)Example** joe@google.com** yazmeen@yahoo.comEmail Message• Consists of:** message text** recipient address** address of sender• Other information may be included providing information about:** who replies should be sent to** subject for the message** date and time stamp• Email clients and servers are used for the processes of preparing, transmitting, receiving and reading emailsEmail Client and Server• Email client, also known as user agent** edit text message** recipient address** carbon copy (cc) / blind carbon copy (bcc)** sends the message to email server• Email server** transmits out-going message** stores in-coming messagesMultipurpose Internet MailExtension (MIME)• Conventional email designed to handle 7-bit ASCII text• Word processed files generally use 8-bit formats• Many Asian languages cannot be mapped to 7-bit ASCII text• Encoding scheme used to convert 8-bit files to 7-bit• Internet standard - MIME** Email client which complies with this standard used to compose and read messages with 8-bit attachmentsFTP• Protocol designed to facilitate copying files from one host to another• Used to retrieve files from Internet archives• Useful for binary and text files• Login identification• Anonymous ftp - no user name and password• Driven by typing simple commandsTelnet• Protocol which allows remote login to server machine• Useful for solving problems with web servers• Simple client program is required to manage connection and display data sent by remote computer• Terminal emulation, for example:** DEC VT100** IBM 3270Telnet Usage• Log in to remote machine using a user name and password• No anonymous login facility (security reasons)• User name and password sent back to remote machine** intercepting packets relatively easy, so this is a major security flaw** extensions to basic telnet protocol can prevent this problem, e.g. SSHNewsgroups• Public bulletin board• Hierarchy of topics• New newsgroups daily, many fall into disuse quickly• Main categories:** comp** news** rec** sci** soc** alt** de, fr, uk• Similar to email, with additional features** ‘threads’ allow responses to be followed in sequence to original posting• Newsreader software required to read and contribute messages** Outlook Express has some simple newsreading capabilities• Contributing may lead to ‘spam’WWW• Resulted from project started by Tim Berners-Lee at the European Laboratory for Particle Physics (CERN)• Modern implementation of hypertext idea developed by Ted Nelson in the 60s• Hypermedia - instead of just text, includes sounds, pictures, etc• Extended to User navigation from document to document through hyperlinksWWW Objectives and Operation• Unify Internet protocols** telnet** ftp** newsgroups• Browser based navigation** recognizes references to other documents and provides links• Content based search engines• Give user access to any type of materialBrowser Features• Home** default website• Forward** move to next resource in current list• Back** move to previous resource• Search** call up a search engine to locate a resourceWWW Architecture• Vast number of web pages connected by links• Pages (resources) - textual, graphics, sound, video, etc or any combination• User can follow a link from one resource to another• Each page is identified by a URLBrowser• User requests web page by specifying URL• Browser:** receives data from web server** interprets the data** displays in an appropriate form** allows user navigation through resourceUniform Resource Locators• Used to specify the location and form of a request to a web server• URL made up of two parts• Scheme refers to the protocol required• Most common choices are:** ftp File Transfer protocol** http Hypertext Transfer Protocol** news USENET news** nntp USENET news using NNTP accessWeb Based Email• Grown in popularity• Website holds all messages** access by connecting to website URL and logging into email with name and password** access from any computer with Internet connectivity• Advantages for travelers, but…** access via a fully graphical website is slow** generally need to be connected for reading and writing (therefore more expensive)** easier for hackers to accessInstant Messaging• Email is not spontaneous** lacks instant feedback of direct communication• Range of Internet applications that fill this gap, mostly based on old UNIX program ‘talk’** conversation through keyboard and screen** extends to ‘conference calls’• Using the Internet, instant messaging has grown in an unstandardised manner** many suppliers providing systems that do not work well together• Several ‘instant message’ services - all popularInternet Relay Chat (IRC)• Similar to the newsgroup idea, but all participants can ‘chat’ on line• Some degree of standardization• Chat rooms share a common theme** users can enter or leave at will and possibly create new chat rooms for different topic• Fast-moving, anarchic, time wasting, BUT…** closed chat rooms useful for business** more productive and less expensive than videoconferencingVoice Over IP• Process:** convert analogue voice to digital data** put data into packets** transmit using TCP/IP (packets follow different routes (possibly), timing unpredictable)** assemble packets back into digital data stream** convert back to analogue signal (with acceptable reproduction of the original audio signal)• Possible large cost advantages** e.g. if the mix of calls includes many higher cost destinations