Background information on Internet Infrastructure.

1. WEB PROGRAMMING
AND INTERNET
TECHNOLOGIES
HENRY OSBORNE

2. OBJECTIVES
• Distinguish between the Internet and the World Wide Web
• Explain client-server architecture
• Discuss how web browsers and servers communicate
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3. WHAT IS THE INTERNET?
• World-wide collection of computers and other devices connected
via communications media
• Started in the 1960s
• Initial development under the auspices of the ARPA (Advanced
Research Projects Agency)
• Other networks developed by late 1970s, early 1980s
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4. CPTR304: Internet Authoring
Visualization of the various routes
through parts of the Internet.
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5. WHAT IS THE WORLD WIDE WEB (WWW)?
• “software infrastructure” consisting of various communications standards for
gaining access to, and exchanging information over, the internet
• Development started in the late 1980s by Sir Tim Berners-Lee and others at
CERN (European Organization for Nuclear Research)
• The idea was to make scientific documents available over the Internet
• HTML was developed for the purpose of describing the structure of
documents
• Browsers, with simple text-based interfaces were used to retrieve and display
the documents (Lynx)
• Mosaic, the first widely used GUI browser
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6. CLIENT-SERVER ARCHITECTURE
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7. HOW WEB BROWSERS AND WEB SERVERS
COMMUNICATE
1.Web Protocols and Layered Communication Architectures
2.Web Addresses and Address Resolution via DNS
3.URLs, URNs, and URIs
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8. 1. WEB PROTOCOLS AND LAYERED
COMMUNICATION ARCHITECTURES
• Communication protocol: an agreement between two or
more parties about what rules will be followed when
communication takes place.
• Web protocol: agreed-upon set of rules and date formats to
be used when two or more computers or other devices, or
application programs running on those machines, wish to
communicate across the Internet.
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9. COMMON WEB PROTOCOLS
• TCP/IP
• UDP
• HTTP/HTTPS
• FTP
• TELNET and SSH
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10. LAYERED COMMUNICATION ARCHITECTURE
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11. 2. WEB ADDRESSES AND ADDRESS
RESOLUTION VIA DNS
• IP Address: has the form a.b.c.d, where each of the values is a positive
integer in the range 0…255 (32-bit address/~4 billion addresses)
• E.g. 74.125.229.243
• FQDN: human-readable version of an IP address
• E.g www.google.com
• Host Machines and domains
• Domain Name System and Domain Name Servers
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12. The logical hierarchy of the Domain Name Service (DNS)
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13. 3. URLS, URNS, AND URIS
• Uniform Resource Locator (URL): a standard way of referring to the location
of a web document/resource
• scheme: address_of_resource
• http://cis.ncu.edu.jm
• Uniform Resource Name (URN): has the same form as a URL but may not
identify an actual location on the Internet.
• urn:isan:0000-0000-9E59-0000-O-0000-0000-2
• The 2002 film Spider-Man, identified by its audiovisual number.
• Uniform Resource Identifier (URI): a string of characters used to identify a
name of a web resource. URIs can be classified as locators (URLs), as names
(URNs), or as both.
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