Transcript Document

Internet
Some slides taken from: Computer Science: An Overview Tenth Edition. J. Glenn Brookshear
Internet
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Networks
The Internet
The World Wide Web
Internet Protocols
Security
Search Engines
Network Classifications
• Scope
– Local area network (LAN)
– Metropolitan area (MAN)
– Wide area network (WAN)
• Ownership
– Closed versus open
• Topology (configuration)
– Bus (Ethernet)
– Star (Wireless networks with central Access
Point)
Network topologies
Network topologies (continued)
The Internet
• The Internet is a global system of interconnected
computer networks that use the standard
Internet Protocol Suite (TCP/IP) to serve billions
of users worldwide.
• It is a network of networks that consists of
millions of private and public, academic,
business, and government networks of local to
global scope that are linked by a broad array of
electronic and optical networking technologies.
Internet Architecture
• Internet Service Provider (ISP)
– Tier-1
– Tier-2
• Access ISP: Provides connectivity to the
Internet
– Traditional telephone (dial up connection)
– Cable connections
– DSL
– Wireless
Figure 4.7 Internet Composition
Internet Addressing
• IP address: pattern of 32 or 128 bits often
represented in dotted decimal notation
• Mnemonic address:
– Domain names
– Top-Level Domains
• Domain name system (DNS)
– Name servers
– DNS lookup
Internet Corporation for
Assigned Names & Numbers
(ICANN)
• Allocates IP addresses to ISPs who then
assign those addresses within their
regions.
• Oversees the registration of domains and
domain names.
Traditional Internet Applications
• Electronic Mail (email)
– Domain mail server collects incoming mail
and transmits outing mail
– Mail server delivers collected incoming mail to
clients via POP3 or IMAP
– Mail clients
• Outlook
• Mozilla Thunderbird
• File Transfer Protocol (FTP)
More Recent Applications
• Voice Over IP (VoIP)
• Internet Radio
– N-unicast
– Multicast
World Wide Web
• Hypertext and HTTP
• Browser gets documents from Web server
• Documents identified by URLs
A typical URL
TCP/IP and DNS
Hypertext Document Format
• Encoded as text file
• Contains tags to communicate with browser
– Appearance
• <h1> to start a level one heading
• <p> to start a new paragraph
– Links to other documents and content
• <a href = . . . >
– Insert images
• <img src = . . . >
Figure 4.9 A simple Web page
Figure 4.9 A simple Web page
(continued)
Figure 4.10 An enhanced
simple Web page
Figure 4.10 An enhanced
simple Web page (continued)
Extensible Markup Language
(XML)
• XML: A language for constructing markup
languages similar to HTML
– A descendant of SGML
– Opens door to a World Wide Semantic Web
Using XML
<staff clef = “treble”> <key>C minor</key>
<time> 2/4 </time>
<measure> < rest> egth </rest> <notes>
egth G,
egth G, egth G </notes></measure>
<measure> <notes> hlf E
</notes></measure>
</staff>
The first two bars of
Beethoven’s Fifth Symphony
Client Side Versus Server Side
• Client-side activities
– Examples: java applets, javascript,
Macromedia Flash
• Server-side activities
– Common Gateway Interface (CGI)
– Servlets
– PHP
Security
• Attacks
– Malware (viruses, worms, Trojan horses,
spyware, phishing software)
– Denial of service
– Spam
• Protection
– Firewalls
– Spam filters
– Proxy Servers
– Antivirus software
Search Engines
• General
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Ask.com (formerly Ask Jeeves)
Baidu (Chinese)
Bing (formerly MSN Search and Live Search)
Cuil
Duck Duck Go
Google
Kosmix
Sogou (Chinese)
Sohu (Chinese)
Yahoo! Search
Yandex (Russian)
Yebol
Search Engines
• Geographical limited scope
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Accoona, China/US
Alleba, Philippines
Ansearch, Australia/US/UK/NZ
Baidu, China
Daum, Korea
Goo, Japan
Guruji.com, India
Leit.is, Iceland
Maktoob, Arab World
Onkosh, Arab World
Miner.hu, Hungary
Search Engines
• Business
– Business.com
– GlobalSpec
– Nexis (Lexis Nexis)
– Thomasnet (United States)
Search Engines
• Enterprise
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AskMeNow: S3 - Semantic Search Solution
Concept Searching Limited: concept search products
Dieselpoint: Search & Navigation
dtSearch: dtSearch Engine(SDK), dtSearch Web
Endeca: Information Access Platform
Exalead: exalead one:enterprise
Expert System S.p.A.: Cogito
Fast Search & Transfer: Enterprise Search Platform
(ESP), RetrievalWare (formerly Convera)
Search Engines
• Other
– Medical
– News
– People
– News
– Real Property
– etc
Google Search
• Advanced Search
– Specify AND also with “ “
– Specify OR by writing OR
– Unwanted words
– Language
– Format
– File type
– Pages in a domain
Google Search
• Advanced Search
– Date
– Rights
– Where keywords are
– Region
Google Addwords Keyword Tool
• How to make your page appear in high
positions in Google Search?
– Sword
– Master Albania
– Cars Albania
– New York Tirana
Google Rankings
• http://www.googlerankings.com/
• Check ranking
– http://www.prchecker.info/
• www,unyt.edu.al
• www.km.gov.al
Google Analytics
• http://www.google.com/analytics/
– Adsense
Exam rules
• Powerpoint 50 pts
• Access
48 pts
• Latex
2 pts
– Only one formula with Latex material open