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ECT 250: Survey of eCommerce Technology

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Assignment 1 is due next week. Web Accounts for homework posting were sent out. ... You do this by double clicking on the folders that appear. Browsing Through Files ... – PowerPoint PPT presentation

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Title: ECT 250: Survey of eCommerce Technology


1
ECT 250 Survey of eCommerce Technology
  • The Internet and the
  • World Wide Web

2
Administrivia
  • Assignment 1 is due next week
  • Web Accounts for homework posting were sent out.
    Check eMail that you gave in the Survey or is
    listed on your Campus Connect profile.
  • If eMail listed on Campus Connect profile is not
    correct, please change this.
  • Questions?

3
Review
  • From Week 1
  • Overview of eCommerce
  • Definition
  • Components
  • Comparison to Traditional Commerce
  • Why eCommerce Unique features
  • Appropriateness of eCommerce
  • History of the Internet

4
Week Two Topics
  • Technology Components
  • Packet Switching
  • Protocols TCP/IP, FTP, HTTP, eMail
  • Purpose, use of various protocols
  • TCP/IP Architecture
  • IP Addresses, URLs, Domains
  • Publishing on the Web In Depth
  • File Transfer Protocol

5
What is the Internet?
  • A loosely configured global wide-area network.
  • Loosely configured open architecture, no single
    control
  • Network connection of computers
  • Wide Area large geographical coverage

6
Factors Behind Growth
  • Primary technology factors behind growth
    discussed tonite
  • The TCP/IP standard and packet switching.
  • The web-like ability to link from site to site
    enabled through HTML and HTTP.

7
A Model for Networking
  • The worlds telephone companies were the early
  • models for networked computers because the
  • networks used leased telephone company lines.
  • Telephone companies at the time established a
  • single connection between sender and receiver
  • for each telephone call.
  • Once a connection was established, data traveled
  • along that path.

8
Circuit switching
  • Telephone company switching equipment (both
  • mechanical and computerized) selected the
  • phone lines, or circuits, to connect in order to
  • create the path between caller and receiver.
  • This centrally controlled, single connection
  • model is known as circuit switching.
  • Using circuit switching does not work well for
  • sending data across a large network.
  • Point-to-point connections for each sender/
  • receiver pair is expensive and hard to manage.

9
A Different Approach
  • The Internet uses a less expensive and more
    easily
  • managed technique than circuit switching.
  • Files and messages are broken down into packets
  • that are labeled with codes that indicate their
  • origin and destination.
  • Packets travel from computer to computer along
  • the network until they reach their destination.
  • The destination computer reassembles the data
  • from the packets it receives.
  • This is called a packet switching network.

10
View of Packet Switching
p. 116 Figure 3.4
11
Packet switching
  • In a packet-switched network, each computer that
  • an individual packet encounters determines the
  • best way to move the packet to its destination.
  • Computers performing this determination are
  • called routers.
  • The programs that the computers use to determine
  • the path are called routing algorithms.
  • Utilizes Transmission Control Protocol/Internet
    Protocol
  • TCP/IP

12
Routing Messages
p.119 Figure 3.6
13
Benefits of Packet Switching
  • There are benefits to packing switching
  • Long streams of data can be broken down into
  • small manageable data chunks, allowing the
  • small packets to be distributed over a wide
  • number of possible paths to balance traffic.
  • It is relatively inexpensive to replace damaged
  • data packets after they arrive, since if a data
  • packet is altered in transit only a single
  • packet must be retransmitted.

14
Questions
15
Protocols
  • A protocol is a set of rules for the exchange of
    data across
  • communication lines.
  • Protocols need to handle the following tasks
  • Format messages
  • Order Data in message
  • Compress message
  • Provide Error checking on message

16
Most Popular Internet Protocols
  • The most popular Internet protocols include
  • TCP/IP Transmission Control Protocol/Internet
    Protocol
  • FTP File Transfer Protocol
  • HTTP Hypertext Transfer Protocol
  • E-mail protocols SMTP, POP, IMAP
  • Each protocol is used for a different purpose,
    but all of them are important.

17
TCP/IP
  • The protocols that underlie the basic
    operation of
  • the Internet are TCP (transmission control
  • protocol) and IP (Internet protocol).
  • Establish rules about how data are moved
    across networks
  • and how network connections are established
    and
  • broken.

18
Purposes of Each
  • TCP controls the assembly of a message into
  • smaller packets before it is transmitted over
  • the network. It also controls the reassembly
  • of packets once they reach their destination.
  • The IP protocol includes rules for routing
  • individual data packets from their source to
  • their destination. It also handles all
    addressing
  • details for each packet. More on addressing
    later.

19
TCP/IP Architecture
20
General Layer Properties
  • Full discussion of the TCP/IP Architecture beyond
  • the scope of this class.
  • Useful to understand where each protocol resides
  • TCP operates in the transport layer.
  • IP operates in the Internet layer.
  • HTTP, SMTP, POP, IMAP and FTP operate in the
  • application layer.

21
Questions
22
File transfer protocol
  • FTP (file transfer protocol) is a part of TCP/IP
  • that allows files to be transferred between
  • computers connected using TCP/IP.
  • It uses the client/server model.
  • FTP permits files to be transferred in both
  • directions, that is, from the client to the
    server
  • or from the server to the client.
  • It can transfer files one at a time or many
    files
  • simultaneously.

23
Files types and FTP
  • FTP allows the transfer of two types of files
  • ASCII text files containing only characters
  • available through the keyboard and containing
  • no formatting information.
  • Example Files created using Notepad
  • Binary data files containing word processed
  • documents, worksheets, graphics, etc.

24
Other Functions of FTP
  • FTP has other useful functions
  • Displaying remote and local computers
    directories
  • Changing the current clients or servers active
  • directories
  • Creating and removing local and remote
    directories.

25
Accessing with FTP
  • There are two ways to access remote machines
  • Full privilege FTP access This requires that you
  • have an account on the remote computer and that
  • you supply your username and password.
  • Anonymous FTP If you do not have an account
  • on the remote computer, you can type anonymous
  • as the username and your e-mail address as the
  • password and obtain limited access to the remote
  • computer.
  • You can use an FTP client program or Web browser
  • interface for FTP.

26
Browsing Through Files
Once you have logged into your account using FTP
you can browse through the files located in your
account. You do this by double clicking on the
folders that appear.
27
FTP with a Browser
  • To use a browser as an interface with FTP
  • Type ftp//yourlogin_at_students.depaul.edu
  • This will bring up a window that prompts you
  • for your password.
  • Type in your password (being careful to type
  • it correctly) and hit enter.
  • The files in your main directory will appear.
    Note Be sure to check that browser doesnt store
    password. Look at Tools/Internet
    Options/Content/AutoComplete.

28
Creating Directories
  • To create a directory on students.depaul.edu
  • using the browser interface
  • Select File
  • Select New
  • Select Folder
  • Click on the folder and give it the name
  • you wish it to have.

29
Moving Files
  • Once you have created a public_html directory,
    you
  • can move your HTML files into that directory.
  • In order to do that
  • Open up the directory into which you wish to
  • move the file.
  • Open the folder where the file is located on your
  • local machine.
  • Select Edit/Copy or drag the file directly into
    the
  • directory.

30
Questions
31
HTTP
  • HTTP (hypertext transfer protocol) is the
    protocol
  • responsible for transferring and displaying Web
  • pages.
  • It has continued to evolve since being
    introduced.
  • Like other Internet protocols, HTTP uses the
    client/
  • server model of computing. Thus, to understand
  • how HTTP works, we need to first discuss the
  • client/server model.

32
Client/Server model
  • In the client/server model there are two roles
    the
  • client and the server.
  • The client process makes requests of the server.
  • The client is only capable of sending a request
  • to the server and then waiting for the reply.
  • The server satisfies the requests of the client.
    It
  • usually has access to a resource, such as data,
  • that the client wants. When the resource that
  • the client wants becomes available, it sends a
  • message to the client.
  • This model simplifies communication.

33
Client/Server Model
Figure 3.7, p.120
34
HTTP and Client/Server
  • With HTTP the client is the users Web browser
  • and the server is the Web server.
  • To open a session, the browser sends a request
  • to the server that holds the desired web page.
  • The server replies by sending back the page or
    an
  • error message if the page could not be found.
  • After the client verifies that the response sent
    was
  • correct, the TCP/IP connection is closed and
  • the HTTP session ends.
  • Each new page that is desired will result in a
    new
  • HTTP session and another TCP/IP connection.

35
One Page, Multiple Requests
  • If a Web page contains objects such as movies,
  • sound, or graphics, a client must make a
  • request for each object.
  • For example, a Web page containing a back-
  • ground sound and three graphics will result in
  • five separate server request messages to retrieve
  • the four objects plus the page itself.

36
Questions
37
Mail protocols
  • Electronic mail is managed and stored by
    programs
  • and hardware collectively known as mail servers.
  • It is displayed and created using mail programs
  • such as Eudora, Pine, Unix mail, Outlook, Web
    interface mail programs.
  • Protocols are necessary for the mail programs to
  • construct requests to receive e-mail and for the
  • mail servers in downloading and/or deleting
    e-mail.
  • The e-mail protocols we will discuss use the
    client/
  • server model.

38
SMTP
  • SMTP (simple mail transfer protocol) is used by
  • client mail programs to make requests about
  • mail delivery.
  • A wide variety of mail programs such as Eudora,
  • Unix mail, and PINE, use SMTP to send mail
  • to a mail server.
  • The SMTP specifies the exact format of a mail
  • message and describes how mail is to be
  • administered.

39
POP
  • POP (post office protocol) is responsible for
  • retrieving e-mail from a server.
  • It requests that the mail server either
    retrieve
  • mail from the mail server and then delete it,
  • retrieve mail from the server without deleting
  • it, or simply ask whether new mail has come
  • but not retrieve it.
  • When e-mail is read, POP specifies that it
    must
  • be downloaded to your computer from the
  • server. Read e-mail is not kept on the server.

40
IMAP
  • IMAP (Internet Message Access Protocol) is a
    newer protocol that, like POP, can ask if there
    is new mail, download e-mail, and delete e-mail.
  • IMAP has capabilities that POP does not
  • It defines how a client program asks a mail
  • server to present available mail.
  • It can allow you to manipulate and manage
  • e-mail without downloading it from the server.

41
Questions
42
Internet Addresses
Internet addresses are represented in several
ways, but all the formats are translated to a
32-bit number called an IP address a function of
Internet Protocol (IP) The increased demand for
IP addresses will soon make 32-bit addresses too
small, and they will be replaced with 128-bit
addresses (IP v6.0) in the near future. How does
increasing the number of bits in the address
help with increasing demand?
43
Dotted Quads
  • IP numbers appear as a series of up to 4
    separate
  • numbers delineated by a period.
  • Examples
  • students.depaul.edu 140.192.1.100
  • condor.depaul.edu 140.192.1.6
  • facweb.cs.depaul.edu 140.192.33.6
  • Each of the four numbers can range from 0 to
    255, so
  • the possible IP addresses range from
  • 0.0.0.0 to 255.255.255.255

44
Elements of Internet Addressing
45
Domain Names
  • Since IP numbers can be difficult for humans to
  • remember, domain names are associated with
  • each IP address.
  • Examples
  • students.depaul.edu 140.192.1.100
  • facweb.cs.depaul.edu 140.192.33.6
  • A domain name server is responsible for the
    mapping
  • between domain names and IP addresses.
  • Domain names and IP addresses are registered
    separately. Registering domain name doesnt
    imply getting an IP address. IP address is from
    hosting service.

46
Uniform Resource Locator
  • People on the Web use a naming convention called
    the
  • uniform resource locator (URL).
  • A URL consists of at least two and as many as
  • four parts.
  • A simple two part URL contains the protocol
  • used to access the resource followed by the
  • location of the resource.
  • Example http//www.cs.depaul.edu/
  • A more complex URL may have a file name
  • and a path where the file can be found.

47
A URL deconstructed
http//www.daschmelzer.com/ect250/hw/h1/h1.htm
hypertext transfer protocol
path that indicates the location of the
document in the hosts file system
domain
document name
This is considered a fully specified URL
48
Anatomy of an eMail Address
dschmelzer _at_ cti . depaul . edu
Domain Type
Handle
Host/Server
Domain
  • Others
  • students
  • hawk
  • condor

49
Shortened URL
  • Simply by typing www.cs.depaul.edu into browser
    allows http to locate specific file
  • Web servers are set to default to specific file
    names when full URL (or filename) not given.
  • index.htm (.html, .asp, .jsp, etc) and
    default.htm (etc) are examples.
  • Name the template file in HW1 index.htm

50
Domain types
  • .com
  • Commercial organizations or businesses
  • .edu
  • Educational institutions
  • .gov
  • U.S. government agencies
  • .mil
  • U.S. military
  • .net
  • Network computers
  • .org
  • Nonprofit organizations and foundations
  • .biz
  • business firms
  • .info
  • information providers
  • .aero
  • Air transport industry
  • .coop
  • Cooperatives
  • .museum
  • Museums
  • .name
  • Individuals
  • .pro
  • Professionals

51
HTML
  • HTML Hypertext Markup Language
  • One of the languages with the parent SGML
    Standard Generalized Markup Language
  • HTML provides Web page designers with a fixed set
    of markup tags that are used to format a Web
    page

52
HTML Example
Page 149, Figure 3.18
53
HTML TOOLS
Page 150, Table 3.7
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