Fall 2000C.Watters1 World Wide Web and E-Commerce Internet and WWW Basics

Fall 2000C.Watters2 Objectives What is the World Wide Web (web or WWW)? How does the web use HTTP and TCP/IP? How do the URLs work? What’s the problem that IPv6 is a solution for?

Fall 2000C.Watters3 So, what is the web?  The Web is a protocol that uses the Internet as the communication structure  The Web links documents stored in computers that communicate on the Internet  Informal sort of arrangement!

Fall 2000C.Watters4 Internet Web Hosts –80 million Servers –80 million x ? web pages –1 billion Web databases –Terabytes x ? delivery content

Fall 2000C.Watters5 Internet TCP/IP protocol for passing data between nodes on the Internet

Fall 2000C.Watters6 Intranet Corporate network using Internet technology but secured behind a firewall Use TCP/IP like the Internet Operate as a private network Connected to the Internet thru firewall

Fall 2000C.Watters7 Public/External Internet Users Intranet Clients Servers ERP Legacy systems servers Web servers Databases Firewalls 7 An Intranet © Prentice Hall, 2000

Fall 2000C.Watters8 Often on a LAN (local Area Network) or WAN (Wide Area Network) Your department is no doubt on an Intranet!! Intranet Examples

Fall 2000C.Watters9 Extranet An extended intranet that connects remote intranets Uses TCP/IP Internet protocols Employs secure channels between the intranets VPN is technology that provides this virtual private network on the Internet

Fall 2000C.Watters10 Tunneling Internet Extranet Intranet Firewall Intranet Firewall 10 An Extranet Suppliers VPN Distributors VPN Customers VPN © Prentice Hall, 2000

Fall 2000C.Watters11 Virtual Private Network (VPN) VPN is a secure network on the Internet using tunneling schemes The major objective of a VPN is to use the Internet rather than a private line ($$) When two sites are connected across a VPN, each must have a VPN-capable router, firewall, or VPN access device installed When VPN is used to link mobile clients with Internet dial-up connections, the laptops must be equipped with VPN client software equipped with the addresses and associated encryption keys for corporate host sites Virtual Private Network (VPN)

Fall 2000C.Watters12 Reduced Product Development Cycle Time: Caterpillar, Inc. –Customers can use the extranet to retrieve and modify detailed order information while the vehicle remains on the assembly line Extranet Cases Sears –Suppliers for just-in-time production Govt. select suppliers and govt. procurement

Fall 2000C.Watters13 The Internet No quality control No central control No guarantees of delivery No guarantees of security No guarantees of privacy No place where the “buck stops”

Fall 2000C.Watters14 The WEB  Communication protocol using the Internet

Fall 2000C.Watters15 Search Engine Sizes (800M) Feb2000

Fall 2000C.Watters16 Basics Web server - machine that services internet request Web client - machine that initiates internet request Browser - software to interact with web data at the client TCP/IP - internet data transfer protocol FTP - internet file transfer protocol HTTP - hypertext transfer protocol HTML - hypertext display markup language

Fall 2000C.Watters17 1. Client-Server & Web Cloud model Based on TCP/IP HTTP and MIME types

Fall 2000C.Watters18 Client-Server Model

Fall 2000C.Watters19 HTTP HyperText Transport Protocol Native protocol for WWW sits on top of internet’s TCP/IP protocol HTTP is a 4 step process per transaction uses a predefined set of document formats from MIME

Fall 2000C.Watters20 MIME defines data types MIME - multipurpose internet mail extensions –defines file formats (images, video, text, etc) –e.g. Content-type: text/html – Data type/subtype » text/html » text/plain » image/gif » video/mpeg » application/msword »etc!!!

Fall 2000C.Watters21 HTTP Connection 1. Client –makes an HTTP request for a web page –makes a TCP/IP connection 2. Server accepts request –sends page as HTTP 3. Client downloads page 4. Server breaks the connection

Fall 2000C.Watters22 HTTP is Stateless!!!! Each operation or transaction makes a new connection each operation is unaware of any other connection each click is a new connection So how do they do those shopping carts??

Fall 2000C.Watters23 What does HTTP look like? Header data + object file Header –plain text –info about the object (MIME etc) –methods allowed –etc browser sends a header to server each time you ask for information server sends a header and possibly content

Fall 2000C.Watters24 HTTP Header Example GET /catalog/ip/ip.htm HTTP 1.0 Accept: text/html Accept: image/gif Referer: User-Agent: Mozilla/2.0

Fall 2000C.Watters25 Side Effect of HTTP transfers  A record is left of all web transactions  Reside in Log files generated at the server  Good news: use-data galore  Bad news: what about user privacy

Fall 2000C.Watters26 Common Log File (CLF) Format cast39.cs.dal.ca - - [12/Jan/2000:16:09: ] "GET /~watters/webcourse/refSer.html HTTP/1.0" hostidentityAuthuserdaterequeststatusbytes

Fall 2000C.Watters27 Footprints (clickprints) What can you do with this data –Rearrange your site –Change your marketing strategy –Make a mailing list

Fall 2000C.Watters28 TCP/IP applications TCP/IP software usually includes: –remote terminal client using TELNET protocol for remote login –electronic mail client using SMTP protocol to transfer to remote system –file transfer client using FTP protocol to transfer files between 2 machines

Fall 2000C.Watters29 2. URLs: NAMES and ADDRESSES What’s in a name, anyway?

Fall 2000C.Watters30 Internet Node Addresses Each node has –unique network name hierarchical composition based on name granting authority –unique network address hierarchical composition based on topographical

Fall 2000C.Watters31 What is the network IP address? 32 bits (4 bytes) per node (IPv4) schemes –class-based addresses –subnet addresses –classless addresses Is there a problem here?

Fall 2000C.Watters32 Class-based Addressing IPv4 General form network.host eg. UC Berkeley is eg. Borg large networks have few network bytes –(more room for hosts on them) small networks have longer network address (fewer hosts expected) What if the host addresses are not all used???

Fall 2000C.Watters33 That may be a big problem!

Fall 2000C.Watters34 IPv6 Features 128 bits address space total 3.4 x addresses Advanced Routing Capability Better Options Support Better Quality of service Support Authentication and Security

Fall 2000C.Watters35 IPv6 Summary IPv6 simplifies packet header formats. IPv6 provides a much larger address space of 128 bits. This overhead in the header has been reduced by simplifying the header formats. IPv6 supports authentication and encryption of packet contents at the network layer.

Fall 2000C.Watters36 IPv4 address transits to IPv6 IPv4-compatible IPv6 address 80 bits 16 bits 32 bits 0000… IPv4 address

Fall 2000C.Watters37 Transition Planning Maintain complete IPv4 routing system until run-out Upgrade IPv4 router to IPv4/6 dual router Building up IPv6 only (6 bone) Shutdown IPv4 in areas where there is no need for IPv4

Fall 2000C.Watters38 How do we get the network address from network name? Domain name servers translate name to network address

Fall 2000C.Watters39 Domain Hierarchy DNS hierarchy can be viewed as a tree –Node in the tree corresponding to a domain. –Leaves in the tree corresponding to the host being named. DNS names are processed from right to left and use period as separator.

Fall 2000C.Watters40 Name Servers do the work Root name server Dalhousie name server Gov. Canada name server …... Cs name server IS2 name server –each name server contains IP addr for each lower level server.

Fall 2000C.Watters41 Domain Hierarchy educomgovmilorgnetukca arizona….mitacmieee csecephysics bascheopt govcanada dal cs

Fall 2000C.Watters42 Name Resolution Client Local name server Root name server Arizona name server CS name server cheltenham.cs.arizona.edu 1 2 Arizona.edu, cheltenham.cs.arizona.edu Cs.arizona.edu, cheltenham.cs.arizona.edu cheltenham.cs.arizona.edu,

Fall 2000C.Watters43 Recap The World Wide Web (WWW or web) is a protocol HTTP is the workhorse of WWW protocol Every click on the web is recorded URL’s need to be mapped into Internet addresses We may run out of Internet addresses IPv6