Bài giảng E-Business and e-Commerce - Chapter 5: Internet Hardware, Software and Communications

Chapter 5, Internet Hardware, Software and CommunicationsOutline5.1 Introduction5.2 Structure of the Internet5.3 Hardware 5.3.1 Servers 5.3.2 Communications Media 5.3.3 Storage Area Networks (SANs)5.4 Connecting to the Internet 5.4.1 Digital Subscriber Lines (DSL) 5.4.2 Broadband 5.4.3 Integrated Services Digital Network (ISDN)  5.4.4 T-1 and T-3 Lines5.5 Internet25.6 Software 5.6.1 Application Service Providers (ASPs) 5.6.2 DatabasesChapter 5, Internet Hardware, Software and CommunicationsOutline5.7 Operating Systems 5.7.1 UNIX 5.7.2 Microsoft Windows 5.7.3 Linux 5.7.4 Mac OS X5.8 Enhancing Business Communication 5.8.1 Intranets and Extranets 5.8.2 Streaming Audio and Video 5.8.3 Internet Telephony 5.8.4 Web Casting and Webconferencing 5.1 IntroductionConnection mediaCost of connectingStreaming media (audio and video)Internet telephony Technologies used to enhance online business communications 5.2 Structure of the InternetIP address (Internet Protocol)Computers use IP addresses to locate other computers on the InternetPacketSource address, a destination address, sequencing information, error-control information and the data to be delivered to the destination address RouterUsed to move packets across the Internet efficiently 5.3 HardwareThe Internet employs many advanced hardware technologies Various communications media used to connect hostsThe roles hosts play on the InternetServersCommunications MediaStorage Area Networks (SAN) 5.3.1 ServersServerA host on the Internet that manages network resources and fulfills requests from clients Web servers, e-mail servers, database servers and file serversA single server may provide multiple services A Web server stores Web pages and delivers the pages to clients upon request Protocols for delivering information over the WebHypertext transfer protocol (HTTP) File transfer protocol (FTP) Post office protocol (POP) Simple mail transfer protocol (SMTP)5.3.2 Communications MediaCommunications medium The hardware that connects computers and other digital equipmentBandwidthIndicates how much data can be transferred through the medium in a fixed amount of timeUsually measured in bits per second (bps)Copper wireThe primary communications medium 5.3.2 Communications MediaFiber-optic cableComposed of flexible glass fiber, is thinner and lighter than traditional copper wire, yet has much wider bandwidth Uses short bursts of light to represent bitsOptical modemModem stands for modulator and demodulatorTranslates digital signals from computers into light through a process called modulationOpto chipConverts the most basic particle of light, the photon, into an electric current Allows tremendous amounts of data to be sent over fiber-optic networks through particles 100 times smaller than the diameter of a human hair 5.3.2 Communications MediaThe strength of a signal transmitted over a communications medium is reduced as the signal travels farther and farther RepeaterCan be used to alleviate this problem by amplifying and retransmitting the signal across segments of copper wire or fiber-optic cableTransmission costsFiber-optic cable is more expensive than copper wire Installation of fiber-optic cable is more complicated than installation of copper wire Fiber-optic cable requires fewer repeaters5.3.3 Storage Area NetworksCompanies produce large volumes of data to support sales analysis tools, enterprise resource planning (ERP) systems, multimedia Web sites and e-commerce systems Storage Area Network (SAN)Provides high-capacity, reliable data storage and delivery on a network Allows network administrators to collect data in logical groups on data servers distributed throughout the networkSAN devices store large volumes of data and may also provide backup and recovery services 5.3.3 Storage Area NetworksMirroring technology A SAN device stores redundant copies of data, so that if one copy is lost or damaged, a mirrored copy can be usedFiber-channel technology A high-speed communications medium based on fiber-optic technology that provides transfer rates of 100 MbpsNetwork storage devices providers EMCCompaqStorageNetworks5.4 Connecting to the InternetMost home users subscribe to an Internet Service Provider (ISP) to connect to the Internet Some charge fixed monthly fees for Internet accessSome offer free Internet access in return for personal demographic data Analog modemUser connects to an ISP using the modem, which then connects the user to the InternetTakes digital signals from the computer and turns them into analog signalsAnalog signals can be transmitted over a telephone line just like a human voiceA modem at the ISP then converts the sound back into a digital signal that can be transmitted over the Internet 5.4 Connecting to the InternetFree Internet access providersNetZeroIsFree.comACIAddress.comWeb TVA low-cost technology for connecting to the Internet through the user’s television, instead of a PC WebTV users can dial into an ISP through a modem to surf the Web, send and receive e-mail and chat with other people The basic WebTV system includes a wireless keyboard, an 8.6-GB, a hard drive and a 56-Kbps modem 5.4.1 Digital Subscriber LinesDigital Subscriber Lines (DSL)Offers high-bandwidth Internet access over existing copper telephone lines Splits your phone line into three information-carrying channels DSL connections require special hardware at the local telephone company’s central office and at the user’s location 5.4.1 Digital Subscriber LinesIAD (integrated access device)Provides network connections for high-speed Internet access, as well as connections for multiple voice telephone lines ADSL (asymmetric DSL) the connection speed for sending data to the Internet (upstream) is slower than the connection speed for receiving data from the Internet (downstream)VoDSL (voice over DSL)Provides voice telephone services and high-speed data access over a single standard telephone lineSDSL (symmetric DSL)Transfers data at the same speed both upstream and downstream5.4.1 Digital Subscriber Lines5.4.2 Broadband BroadbandA category of high-bandwidth Internet service provided mainly by cable television and telephone companies to home usersCan handle voice, data and video informationEnables videoconferencing, real-time voice and streaming-media applicationsAlways connected, eliminating the need to dial into an ISP Cable modemTranslates digital signals for transmission over the same cables that bring cable television to homes and businessesConnections is shared among many users 5.4.3 Integrated Services Digital Network (ISDN)ISDN (Integrated Services Digital Network)Provides high-speed connections to the Internet over both digital and standard telephone lines Limited service Costly connectionDivided into three channels that each perform different tasksTwo bearer channels each support data transfers, while the data channel is used to transmit routing information ISDNZone 5.4.4 T-1 and T-3 LinesT-1 lineA dedicated connection that supports data rates of 1.544 Mb per secondMade up of 24 channelsT-3 lineSupports data rates of 43Mbps and is made up of 672 channels that each support 64Kbps T-1 and T-3 lines can be used for both voice and data communication Everythingt1.com 5.5 Internet2Consortium developing next generation of the Internet AbelineA high-speed network currently used by Internet2 consortium members, will soon be able to transfer 2.4 gigabits of data per second TeleimmersionAllows users in different locations to share information in real time—even 3D images Virtual laboratoryEnable researchers worldwide to collaborate on projectsDigital libraries Storage of audio and video files, enabling a search for a movie by a line from its soundtrack. 5.6 SoftwareApplication Service ProvidersDatabases5.6.1 Application Service ProviderProvide customized business software applications over the InternetMaintains and updates the application as necessaryCompanies can eliminate the costs associated with developing and maintaining business applicationsVirtual private networks (VPNs)Allow customers to connect to their applications securely over the Internet VPNs use the point-to-point tunneling protocol (PPTP) to create a secure channel of communication between the customer and the ASP 5.6.2 DatabasesDatabaseAn integrated collection of data Database management system (DBMS) Provides mechanisms for storing and organizing data in a manner that facilitates satisfying sophisticated queries and data manipulationsStructured Query Language (SQLAlmost universally used with relational database systems to make queries (i.e., to request information that satisfies given criteria) and manipulate data 5.6.2 DatabasesRelational database model A logical representation of the data that allows the relationships between the data to be considered independently of the physical implementation of the data structures Popular enterprise-level relational database systems:Microsoft Sequel ServerOracle Sybase DB2 Informix5.7 Operating SystemsOperating system (OS) Software that manages the resources on a computer Multiuser OS Allows more than one user to run programs simultaneouslyMultiprocessor OS Controls a computer that has many hardware CPUsMultitasking OS Allows multiple applications to run simultaneouslyMultithreading OS Allows an individual program to specify that several activities should be performed in parallel Major operating systems used in desktop computers are UNIX , Linux , Macintosh and Windows 5.7.1 UnixMultics“All things to all people” Bell Laboratories, General Electric and Project MACUnixDeveloped by Bell Laboratories after leaving the Multics projectFirst version written in assembly language Unique design and coherence Met the needs of programmers who were building software and of administrators who control software development efforts 5.7.1 UnixUniversity of California at BerkleyFrom time sharing to systems appropriate for studying distributed computing environments Sun MicrosystemsSun OSInclude facilities for supporting a graphics, window-based, mouse-oriented interfaceProvided facilities for diskless workstations to use the network for file storing, sharing and paging The Open GroupControls the specification for UNIX and holds the trademark www.unix-systems.org 5.7.2 Microsoft WindowsThe most popular operating system in the worldIntroduced in 1984 with graphical user interface (GUI) added to the DOS system Windows 2.0Failed to make a large impact in the marketTook too long to open applications, change screens, etc. Windows 3.0 Achieved widespread success Windows 95Introduced a new graphical user interface and increased performanceWindows 98, Windows NT and Windows 2000 5.7.3 LinuxLinuxA UNIX-like operating system that has been developed by volunteers worldwide Initially developed by Linus TorvaldsGreatest success on the server-side Version 1.0Released in 1994, gained market share to become one of the world’s most widely used operating systemsThe Gnome FoundationFounded to develop a free Linux-based desktop environment and a free application framework to compete with Microsoft Office for the desktop-computer environment 5.7.3 LinuxOpen source softwareFreely available source code, so that anyone can use, customize and make updates to the softwareKernelThe core of the operating system Most of the applications that run on Linux are freely available over the Internet and on many CD-ROM distributions GNU General Public License (GPL) One of the most widely used open-source licenses Requires that the source code for GPL-licensed software, as well as the source code for any modifications or improvements to that software, is made freely available to the publicMicrosoft.NETMicrosoft.NETWeaves together the operating system, the Internet and each device to create applications and services to be accessed anytime, anywhere, from any device Could potentially support UNIX and LinuxBuilding and maintaining .NET componentsWindows.NETVisual Studio.NET Integrated development environment (IDE).NET Enterprise Servers and the .NET framework .NET applications will be built with XML 5.7.4 Mac OSXAchieved great success in the 1980s, dominating the market for GUI-based personal computers One of the first widely available systems to use a window-based (i.e., a GUI) interface, a mouse and icons Release of Windows challenged MacIntosh salesMac OS X operating systemCore was built using industry open standards based on UnixAquaNew Mac OS X interface Internet AppliancesInternet appliances Desktop devices designed specifically for connecting to the InternetiPAQ Home Internet ApplianceNetpliance i-openerDevices allow you to browser the Web, send and receive e-mail and access streaming media onlineLimited functionality 5.8 Enhancing Business CommunicationIntranetsExtranetsStreaming audio and video Internet telephony Makes PC-to-PC and PC-to-phone calls possible, dramatically reducing the cost of communication Web castingVirtual conferencingWireless technology5.8.1 Intranets and ExtranetsIntranetAn organization’s internal network that uses the TCP/IP protocols of the InternetOnly authorized parties, such as the organization's employees, have access to an organization’s intranet Used to store internal informationExtranet An intranet that is also accessible by authorized external parties who are not members or employees of the organizationMembers or employees might have unrestricted access to information on the extranet, whereas customers or vendors might have access to a limited subset of that information 5.8.2 Streaming Audio and VideoStreaming technologiesAllow users to send and process audio and video data continuously Allows users to start playing the audio or video file while it is still downloading Users can play music over the InternetUsers can watch a small video on a Web site5.8.2 Streaming Audio and VideoRealPlayer dialog. (Copyright© 1995-2000 Realnetworks, Inc. All Rights Reserved. RealNetworks, Real.com, RealPlayer are trademarks registered trademarks of of RealNetworks, Inc.)5.8.3 Internet TelephonyInternet telephonyEnables communication over the Internet, allowing you to use your PC as a telephoneCost efficientNet2PhoneService allows you to make free PC-to-telephone calls within the United States, and international calls at discounted rates Net2Phone and other Internet telephony services are not always compatible with systems running firewalls ClickTogether service allows companies to add personalized voice capabilities to a Web site 5.8.4 Webcasting and Web ConferencingWebcasting Broadcasting over the WebBusinesses can stream seminars, conferences, shows, sales presentations and more though their Web sitesLive or prerecordedWeb conferencingAllows businesses to meet and collaborate online, in real time from anywhere in the world EvokeWebcasting and Web conferencing