CSCI 109
Chapter 6:
Internet
1
What happens in an Internet Minute?
What Happens in an Internet Minute
Source: Intel/ Facebook
2
What is the Internet?
• A global system of
interconnected
computer networks
• Uses the standard
Internet Protocol
Suite (TCP/IP)
3
Benefits of Internet
• Internet carries
information resources
and services
– inter-linked hypertext
documents of the World
Wide Web (WWW)
– supports electronic mail,
Skype, Twitter, etc.
4
History
• Cold War and
Space Race
• Need for fault-tolerant
communications
network
– Survive nuclear
explosions
Sputnik 1 replica
Audio: Telemetry
Source: Wikimedia
5
ARPANET
• Data sharing
between
universities and
government
research facilities
ARPANET, 1969
• Speed was
increased from
2.4 Kbps to
50 Kbps by 1967
6
ARPANET
• Funded via
National Science
Foundation
• Backbone speed
increased over time
– By 1985 it was 45
Mbit/s
Representation of ARPANET
as of September 1974
Source: Wikimedia
7
NSFNET
• ARPANET evolved
into NSFNET
• 1995 NSFNET
decommissioned
– Commercial ISPs
took over
NSFNET in 1991. Backbone nodes are shown at
top, regional networks are below.
Source: Wikipedia
8
Commercialization
• 1990’s – open to
commercial use
– Sale of products; business
to business (B2B) and to
consumers (B2C)
– Advertising
– Communications
• By 2018 – over 4 billion
people use the Internet
9
Bandwidth demand
• Growth of Internet usage led
to use of new technologies
• Optical carrier (OC) lines
(fiber optics)
– Applied to networks in 1970
– Uses light pulses over silicon
(instead of electrical charges
over copper cable)
– High speed transmission
medium
10
Optical Carrier lines
• OC-1, -3, and -12 are used
for smaller, or local
connections
• OC48 – used by regional
ISPs
• OC192 - most common
backbone for large ISPs
Transfer rates by OC type
• OC-1 – 51.84 Mbit/s
• OC-3 – 155.52 Mbit/s
• OC-12 – 622.08 Mbit/s
• OC-24 – 1,233.16 Mbit/s
• OC-48 – 2,405.37 Mbit/s
• OC-192 – 9,621.50 Mbit/s
• OC-768 – 39,813.12 Mbit/s
11
Transoceanic OC
• Referred to as submarine
networks
• High speed, large capacity
– 40 Gb/s
– Next generation: 100 Gb/s
www.submarinecablemap.com
African undersea cables
Source: S. Song/ Flickr
12
Who is in Charge?
• No one entity owns the
Internet
• LANs, WANs, etc. are
owned by universities,
corporations, individuals,
government agencies, etc.
• No central governance
13
ICANN
• Internet Corporation
for Assigned Names
and Numbers
• Organization that
directs:
– Internet Protocol
address space
– Domain Name System
14
Internet Engineering Task Force
• Goal: to make the
Internet work
better
• Focus upon core
protocols
– IPv4
– IPv6
• Non profit
15
Influencing organizations
• ISOC -- Internet Society
• IAB -- Internet Architecture Board
• IRTF -- Internet Research Task Force
• IANA -- Internet Assigned Numbers Authority
• NSI -- Network Solutions
• NSF -- National Science Foundation
16
Free Speech
• Not universal
• Internet censorship exists in
some countries
• Internet ‘kill switch’ sought
– Used during cyber attack on
Senator Susan Collins, for Maine,
energy grid, financial
institutions, etc.
Sponsor of contentious kill
switch bill.
Source: Public Domain
17
How the Internet Works
• Internet uses
– Circuit switching
– Packet switching
18
Circuit switching
• Reliable, semi-permanent "pipeline“
• Most commonly used in dedicated
telecommunications
• Guaranteed, reserved bandwidth
19
Packet switching
• Data broken into packets sent independently
through Internet and reassembled on other
side
• Data likely to take different paths
• TCP/IP
Internet Packet Switching
Source: Wikimedia
20
Packet Switching
• Doesn't define a set route for data
• Network disruptions can be circumnavigated by
re-routing
Rerouting of a message
Source: Wikimedia
21
How the Internet Works
• Both methods are used: circuit & packet switching
• Both involve multiple computers to receive and
forward data for us
– i.e., there are intermediate nodes (computers) along the path
• Most data is not encrypted for privacy
– "bad guys" may spy on, or in some cases modify data as it is
sent from one end of the path to the other
22
How computers communicate
• Client server
• Peer to peer
23
Client-server model
• Tasks partitioned between:
– providers of resources (servers)
– and service requestors (clients)
Client Server Model
Source: Wikimedia
24
Client-server model
Client Server Model
Source: P. Mullins
25
Peer-to-peer
• Distributed application
architecture
– Partitions tasks or
workloads between peers
• File originates from
server, but subsequent
sharing is direct from
client to client.
• Peers are equally
privileged
P2P network file sharing
Source: Wikimedia
26
Protocols
• Rules for communicating
• HTTP
– HyperText Transfer Protocol
– Supports WWW
communication
27
TCP (Transmission Control Protocol)
• Responsible for:
– Packet creation
– Reassembling packets in the correct order at the end
– Error checking
– If necessary, TCP will request that a packet be resent
28
IP (Internet Protocol)
• Used to route information to the proper address
• IP protocol uses IP address
– All packets have “send to” IP address to indicate
destination
– Routers direct traffic using IP address tables
– Packets pass through a number of routers before
arriving to destination
29
Common Protocols
• SMTP (Simple Mail Transfer Protocol)
– supports email
• FTP (File Transfer Protocol)
– supports reliable transfer of files
• POP3 (Post Office Protocol)
– supports web-based email clients
• VoIP (Voice over Internet Protocol)
– supports Internet telephony
30
Networks
• Internet
– Connecting two or more networks together
• Intranet
– Allows local communication only
• Extranet
– Used by businesses to allow controlled access
via public Internet to select information
31
VPN
• Virtual Private Network
• Means to create Intranets and extranets over
the public Internet
– Creates a secure private network
– Blocks general Internet users
32
HTTPS
• HTTPS URLs begin with "https://"
– Hypertext Transfer Protocol Secure
• Provides encrypted communication to prevent
eavesdropping
– Securely identifies the web server with which you are
communicating
• HTTP is insecure
– subject to man-in-the-middle and eavesdropping
attacks
– these let attackers gain access to website accounts and
sensitive information
33
Cloud computing
• Use of and access to
multiple serverbased computational
resources via a
network
• Concerns over data
privacy and potential
loss of data
Source: Wikipedia
34
Cloud Applications
• Google docs and GMail
• Storage
– Dropbox
– iCloud
– Google Drive
Gmail
Source: Flickr/ G. Sampson
35
World Wide Web
• WWW or W3 or Web
• System of interlinked
hypertext documents
accessed via the Internet
• Proposed in 1990
– By Sir Tim Berners-Lee
Tim Berners Lee
Source: Wikimedia
36
Addressing
• Web browsing uses web address
– Uniform Resource Locator (URL)
– http://www.erau.edu
• Email: user@host.com
• Host names
– IP addresses – series of numbers
– Domain name system – looks up numbers so we don’t
have to
37
IP address
• Domain Name System (DNS)
– URL converted to numbers
en.wikipedia.org
converts to:
208.80.152.2
IP Address Components
• Uses dotted decimal notation
Source: public domain image
38
DNS Lookup
DNS Lookup for web page
Source: P. Mullins
39
HTML (Hypertext Markup Language)
• Describes how the browser should display the text and content
• Uses tags to indicate how to format. Sample Code:
<html>
<head>
<title>World Wide Web Wikipedia, the free
encyclopedia</title></head>
<body><p>The <b>World Wide
Web</b>, abbreviated as
<b>WWW</b> and commonly
known the <b>Web</b>), is...
</p>
</body>
</html>
Results of the HTML, displayed using Firefox
Source: P. Mullins
40
Web browser
• Software app used to view
web pages
• May contain text, images,
videos and other multimedia
• Navigate between them via
hyperlinks
41
Linking
• Hyperlinks
– Link to resources: related pages, images, downloads,
documents, or other items.
– Just a link appears – example: MLB
• HTML code for hyperlink:
<a href="http://www.erau.edu">University home page</a>
• Over time web resources move, disappear or are
replaced
– Challenge to keep pages updated to new links
– Interest in creation of web archive
• Example: Internet Archive
42
Web portal
• A web site that is a point of access to information
on the World Wide Web
• Presents information from diverse sources in a
unified way
• Benefits:
– Provide a consistent user experience
– Access control
• Public web portals are AOL, Excite, MSN,
Netvibes, and Yahoo!
43
Search Engines
• Deigned to search for information on the World
Wide Web and FTP servers
– Keywords entered to initiate search
– Results are generally presented in a list
– May consist of web pages, images, videos,
documents, etc.
– Examples: Google, Dogpile, Yahoo!
• Some search engines mine data available in
databases or open directories
44
Search Engine Data Mining
• Provides insight into search patterns
– http://www.google.com/trends/
45
Spiders
• Also called crawlers, bots, robots, agents)
• Looks through the World Wide Web following
links between web pages
• Indexes the words on the sites
• Benefits:
– Helps minimize the time searching for information
– Increases the amount and quality of information
46
Web Generations
• Web 1.0, 2.0, 3.0...
• New capabilities
emerge over time
• Means to
communicate and
connect with your
audience shifts
Web 2.0
Source: Flickr / D. Pigatto
47
Web 1.0
• Static Web pages were through most of the 90's
– Content changed only when someone manually edited the
page.
• Late 90's… web sites becoming dynamic and interactive
– User did not always have to specifically request information
– Sometimes requested automatically or "pushed" to the user's
page.
– Web became more interactive and "social"
• The term Web 2.0 was coined in recognition of new
capabilities
– Web 1.0 is what came before
48
Web 2.0
• Offers users the freedom to
contribute
– Opens the possibility for debate
and collaboration
– Also opens the possibility for
"spamming" and "trolling“
• Characteristics of Web 2.0 are:
–
–
–
–
–
–
rich user experience
user participation
dynamic content
Metadata
web standards
scalability
Web 2.0 tag cloud
Source: Wikipedia
49
Web 2.0 Timeline
Timeline of web application development
Source: Radarnetworks.com
50
Web 2.0 Landscape
Source: Flickr
51
Web 3.0
• Definitions vary
• Important features:
– Personalization
– Semantic Web
• This refers to a smarter Web where web based data is
shared and reused across applications for both human
and computer use.
52
Web browser
• Software application for retrieving, presenting,
and traversing information resources on the
World Wide Web.
• Information resource is identified by a Uniform
Resource Identifier (pointed to by a URL)
– a web page, image, video or other piece of content.
Browsers are primarily intended to access the World
Wide Web
– Can also access information provided by web servers
in private networks or files in file systems.
53
Web browser
• Usage statistics of web browsers (May, 2018)
10.9%
3.2%
1.6%
3.9%
79.0%
Chrome
Edge/ IE
Firefox
Safari
Opera
54
Internet Applications
• Many applications use the Web
• Some are installed on the computer and others
accessed via web pages
• The next few slides focus on some of the most
popular communications mechanisms (media)
of the Internet
55
Electronic Mail
• Method of exchanging
digital messages from an
author to one or more
recipients.
• Modern email operates
across the Internet or other
computer networks.
Source: Flickr/ Micky
56
Electronic Mail
• Email servers accept, forward, deliver and store
messages.
– Neither the end users nor their computers are
required to be online simultaneously, they need
connect only briefly, typically to an email server,
for as long as it takes to send or receive
messages.
57
Parts of E-Mail
• An email message consists of three components:
– the message envelope
– the message header
– the message body
• Message header contains control information
–
–
–
–
originator's email address
one or more recipient addresses
subject header field
message submission date/time stamp
58
SMTP
• Simple Mail Transfer Protocol
• Internet standard for electronic mail
transmission across IP networks
59
How e-mail works
Sequence of events that takes place when composing/sending/receiving e-mail
Source: Wikimedia
60
Webmail
• Accessed through the web and stays on the
web (somewhat like cloud computing)
• Main benefit:
– user can access their mail from any location with
any computer that has an Internet connection and
a web browser
• Examples:
– Gmail, Hotmail, ERAU’s web access
61
Newsgroup
• Repository usually within the
Usenet system
• Messages posted from many
users in different locations and
open to anyone.
• Newsgroups are technically in a
distinct form functionally similar
to discussion forums on the
World Wide Web.
• Newsreader software is used to
read newsgroups
Usenet Big Nine Top level of
subject hierarchies
(For example:
alt.binaries.games.xbox360)
Source: Wikimedia
62
Discussion Board
• Online site where people can hold conversations in
the form of posted messages
• A forum is hierarchical (tree-like) in structure
– Can contain subforums, each of which may have several
topics
– Within a forum's topic, each new discussion started is
called a thread and can be replied to by as many people
as wish to
• Some may permit anonymous posts; others require
registration
– Usually, users do not have to log in to read existing
messages
63
Instant Messaging (IM)
• Form of real-time text-based
communication
–
–
–
–
Between two or more people
Using PCs or other devices
User's text is conveyed over the Internet
IM software may have live voice or video
• Based on communications between
specified known users
– "Buddy List", "Friend List“, "Contact List“
– Users informed when buddy is available
Pidgin 2.0 contact window
Source: Wikimedia
64
Twitter
• Social networking and microblogging service
• Enables users to send and read messages called tweets
• Tweets are text-based posts of up to 280 characters
– Displayed on the user's profile page
– Are publicly visible by default
– Senders can restrict message delivery to just their followers
65
Tweeting
• Users can tweet via
– The Twitter website
– Compatible external
applications (smartphones)
– By Short Message Service
(SMS) used to send text
An SMS message
messages on phones.
66
Facebook
• Social networking service and web site
• Users may create a personal profile and customize
their memberships and relationships
– Add other users as friends and exchange info
– Automatic notifications with profile updates
– Join common-interest user groups, organized by
workplace, learning institutions, or created by an
individual
67
Facebook
• 2018, 1st Quarter:
– More than 2.19 billion monthly active users
– This is approximately one out of every 4 people on the planet!
68
Facebook Breakup
69
VOIP
• Voice over Internet Protocol
• Type of internet telephony
– Internet is used to make phone
calls or send messages
– Either one on one or for audioconferencing.
– Can make long distance phone
calls that are very low cost or
even free.
Home phone using VoIP
Source: Wikimedia
70
Skype
• A peer-to-peer software
application that allows users
to make voice and video
calls and chats over the
Internet.
• Calls to other users within
the Skype service are free.
• Calls to both traditional land
line telephones and mobile
phones can be made for a
fee using a debit-based user
account system.
Skype
Source: J. Ovington/ Flickr
71
Webcast
• Media file distributed over the
Internet
– Uses streaming media
technology
– Distributes a single content
source to many simultaneous
listeners/viewers
– May either be distributed live or
on demand
– Is "broadcasting" over the
Internet
Typical Webcast
Source Wikimedia
72
“Webcasters"
• Radio and TV stations that "simulcast" output
• Many Internet only "stations"
Logik Internet Radio
(now discontinued)
Source: Flickr
73
Webcast
• IBM Cloud Video
– A video streaming service
– Anyone can use to create their
own channel
– Mobile players available for
Smartphones
74
Podcast
• Series of digital media files (either audio or
video)
– Released episodically
– Often downloaded through web syndication
• Term Podcast replaced webcast
– Due to success of the iPod and its role in the
rising popularity and innovation of web feeds.
• Audio or video files in a series is maintained
centrally on the distributor's server as a web feed
75
Podcatcher
• Software that catches a
feed
• Checks for updates and
downloads any new files
in the series
• Examples:
– iTunes
– Podcatcher
– Zune
–
Mozilla Firefox RSS feed icon
Source: Wikimedia
http://en.wikipedia.org/wiki/List_of_podcatchers
76
YouTube
• A video-sharing website
– Users can upload, share and view videos
• Uses HTML5 technology
• “YouTube has over a billion users — almost one-third of all
people on the Internet — and each day those users watch a
billion hours of video, generating billions of views.”
– http://www.youtube.com/t/faq
77
YouTube Content
• User-generated video content includes
– Movie and TV clips
– Music videos
– Mashups
– Amateur content such as video blogging and short
original videos
– Most of the content has been uploaded by individuals
78
YouTube Content
• Unregistered users may watch videos
• Registered users may upload unlimited number of videos
• 18+ age restriction for videos that are considered to
contain potentially offensive content
79
HTML5
• A language for structuring and presenting
content for the World Wide Web
– Finalized, Oct. 2014
• Core aims:
– Improve support for multimedia
– Upgrade prior versions of HTML
• HTML4 and XHTML
80
Wiki
• A web site that allows the creation and editing
interlinked web pages
– Via a web browser
– Uses simplified markup language, or a WYSIWYG (what
you see is what you get) text editor
• Typically powered by wiki software
• Often used collaboratively by multiple users
–
–
–
–
Community web sites
Corporate intranets
Knowledge management systems
Note services
81
Wiki examples
Wikispaces
PBWorks
82
Blog
• Blend of web log
• Type or part of a web site
– Usually maintained by an individual
– Regular entries of commentary, descriptions of events,
or other material such as graphics or video
– Entries are commonly displayed in reversechronological order
• Can be used as a verb, meaning to maintain or add
content to a blog
• Provides interactivity
• Allows visitors to leave comments
83
Blog Topics
• Reflect the thoughts, opinions and biases of
the author
– Many provide commentary or news on a
particular subject
– May be personal online diaries
• Combine text, images, and links to other
blogs, web pages and other media related to
its topic
• Free blogs: Blog.com and WordPress
84
Blog Topics
• Most primarily textual; others include:
–
–
–
–
–
art (art blog)
photographs (photoblog)
videos (video blogging)
music (MP3 blog)
audio (podcasting)
Screenshot of blog page
Source: www.artbozblog.com
85
Microblogging
• A type of blogging
– features very short
posts
• Examples:
– Twitter and Facebook
status updates
Mobile version of Twitter
Source: Wikipedia
86
Last Slide
End
87