Evolution of World Wide Web Technologies

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Nov 10, 2013 (3 years and 9 months ago)

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Evolution of World Wide Web Technologies




by Adrienne Sonder

LIS392P.12
-

Problems in the Permanent Retention of Electronic Records

Dr. Patricia Galloway

Spring 2003

CONTENTS


Origins of the Internet



Development of the World Wide Web and it’s technologies



Impact on web archiving

EARLY COMPUTER NETWORKING


Time
-
shared computers


Central location


Contained to locality


Circuit
-
switching


Dedicated channel, or, “circuit” opened for the duration of the
transmission.


Transmission flowed in one, synchronous stream.


Limited computer communication to only one other computer at a
time.


ARPANET


Packet
-
switching: enabled a robust networking system that
could still function if part of it was down.


Messages broken into packets.


Each packet transmitted individually.


Each packet could follow a different route to its destination.


At destination, packets were reassembled into original transmission.


NETWORKING PROTOCOLS


“Internetting”


to communicate with another computer on
the network required that your computer run the same
communications protocol.



A number of protocols were in use until 1983, when TCP/IP
(Transfer Control Protocol/ Internet Protocol) became the
official protocol of ARPANET. This date is often
considered the birth of the Internet.



TCP/IP
-
A suite of protocols.

Among the protocols included in the TCP/IP suite:


File Transfer Protocol (FTP)
-

for file delivery and
retrieval.


Computer mail
-
allowed computers to send electronic
mail to each other.


Telnet
-
allowed remote login into other computers on the
Internet.


Gopher
-
later added to the TCP/IP protocol suite.
Allowed users to locate and examine files on other
computers on the Internet.

WORLD WIDE WEB DEVELOPMENT


Tim Berners
-
Lee and Robert Cailliau develop a hypertext
system that enabled users to publish information on the
Internet.


Hypertext Markup Language (HTML)


For formatting the information


Hypertext Transfer Protocol (HTTP)


For transferring the information


Browser


For locating the information. Through the use of a URL, users could
locate an arbitrary file, in an arbitrary format, from an arbitrary
machine.


BROWSERS


Browsers that understand HTTP:


Mosaic


Point and click capabilities


Included an <img> (image) tag within its specifications, allowing users
to produce web documents with inline graphics. Netscape: Commercial
version of Mosaic


Netscape


Expanded multimedia capabilities, more than just <img> tag


Free!


CLIENT
-
SERVER COMMUNICATION ON THE
WWW


Static HTML pages:



Browser (client) sends http request to server which responds with
file content.



Static HTML documents often contain hyperlinks on one page that
generate a request for another document on the same or different
server.

CLIENT
-
SERVER COMMUNICATION ON THE
WWW

(cont’d)


Client
-
server communications became more versatile.


Dynamic web content: Content that is created in response to
user input.


CGI (Common Gateway Interface)
-


A standard for interfacing external applications with information servers.


Server
-
side scripting: Script is contained in the requested document
and is executed as server processes it.


Examples:
Active Server Pages using Microsoft's special Visual Basic
scripting, Cold Fusion pages using Allaire's ColdFusion Markup
Language, or PHP pages (originally known as "Personal Home Page
Tools") with PHP markup

CLIENT
-
SERVER COMMUNICATION ON THE
WWW

(cont’d)

Other options for creating dynamic web content
-

Client
-
side scripts


Scripts embedded in the HTML page that manipulate data submitted by
HTML FORM tag


Examples: Javascript, Vbscript, Perlscript, Java applets, Active X
controls


Effects: In many cases, used to produce graphical effects or animation in
the user’s browser environment.

PROBLEMS WITH PERMANENCE


Capturing the interactivity of the Web is difficult. Adds a
whole new element to be preserved.


Issue of the Deep Web


What are the boundaries of an individual site? What is OK
not

preserve?


Server
-
side applications require browser plug
-
ins that
sometimes are not widely available.


Wide variety of formats. Browsers only display the most
popular.