Section 1.1. An Intergalactic Network


1.1. An Intergalactic Network

Pages could be filled by listing all the people who have made significant contributions to the origin and evolution of the modern Internet. But one person laid the intellectual foundation: J. C. R. Licklider, a remarkably modest man who insisted on being called "Lick" rather than "Dr. Licklider" and who was comfortable letting others take credit for his ideas. Licklider had both a wide-ranging curiosity and (according to him) a short attention span. Combined with a gift for problem solving, these characteristics made him a generalist with deep insights into a number of fields. The fact that he was a psychologist, not an engineer, explains why his early ideas about computing and networking centered more on their cultural role than on technology.

While researching psychoacoustics at MIT in the mid-1950s, Licklider developed an intense interest in computers as a tool for modeling human cognition. During this time, and later as a vice president of Bolt Baranek and Newman (BBN), a consulting firm specializing in acoustic engineering, he and his protégés began fomenting ideas on computers as cognitive and communications tools. So deep was his immersion that by the very early 1960s Licklider, who had known little about computers before 1955, had become a widely recognized leader in computer science.[1] His seminal ideas were presented in various memos and later in two important papers, "Man-Computer Symbiosis" and "The Computer as a Communication Device."[2]

[1] Lick foresaw home computers, graphical user interfaces, point-and-click input devices, and many other aspects of the modern computing. His work also made him the father of artificial intelligence.

[2] J. C. R. Licklider, "Man-Computer Symbiosis," IRE Transactions of Human Factors in Electronics, Volume HFE-1, March 1960, and "The Computer as a Commmunication Device," Science and Technology, April 1968.
Reprints of both papers, with an introduction by Bob Taylor, can be found on the Web as "In Memoriam: J.C.R. Licklider, 19151990," gatekeeper.dec.com/pub/DEC/SRC/research-reports/SRC-061.pdf, published by the Systems Research Center of Digital Equipment Corporation, August 1990.

One of the key ideas promulgated by Licklider, discussed in "Man-Computer Symbiosis," was real-time, interactive computer processing. In the 1950s, computations were done by batch processing: You formulated the problem and worked out a program to compute the solution to the problem. The difficulty with batch processing is that the very process of solving a complex problem can change the original question. Unforeseen alternatives mean going back to the beginning and creating another batch program. Licklider quoted Poincare: "The question is not, 'What is the answer?' The question is, 'What is the question?'" Real-time interaction between human and computer allows the question to be modified to accommodate new information discovered during the problem-solving process.

Batch processing also means that the computer runs one program at a time; everyone must wait his turn. If interaction with the computer is to take place in real time, multiple people should be able to use the computer concurrently. An extension to the idea of real-time interactive computing, then, is time sharing.

Another idea discussed in the same paper is the concept of a computer as a supplemental component in the human thought process. Using his own typical workday as an example, Licklider determined that most of his activities were clerical or mechanical: "About 85 percent of my 'thinking' time was spent getting into a position to think, to make a decision, to learn something I needed to know. Much more time went into finding or obtaining information than into digesting it." Computers are much faster at finding and coordinating information than we are; the symbiosis of man and computer applies the computer to the drudgery of information retrieval and data processing, leaving us free to direct the problem-solving process as new information presents itself.

Out of these ideas springs yet another, that of "thinking centers." If a computer is to be used for information retrieval, it might need access to vast amounts of datamore than a single computer can hold. Licklider's idea of a thinking center was multiple computers interconnected over a wide area, comprising a new kind of library. A user at any computer had access to the information on any computer in the thinking center. This, of course, brings us to the core concept of a WAN-based internetwork.

The idea put forth in "The Computer as a Communication Device" is not just that networked computers can link humans over wide areas, but that they can assist in the basic psychology of communication. "Creative, interactive communication requires a plastic or moldable medium that can be modeled, a dynamic medium in which premises will flow into consequences, and above all a common medium that can be contributed to and experimented with by all." Licklider saw the computer as this medium, creating models that the human mind does not: "By far the most numerous, most sophisticated, and most important models are those that reside in men's minds. In richness, plasticity, facility, and economy, the mental model has no peer, but, in other respects, it has shortcomings. It will not stand still for careful study. It cannot be made to repeat a run. No one knows just how it works. It serves its owner's hopes more faithfully than it serves reason. It has access only to the information stored in one man's head. It can be observed and manipulated only by one person." This concept builds on the earlier ideas of man-computer symbiosis, but takes us well into the basic concepts of using a wide-area network for distributed data processing.

In October 1962, Licklider was hired by the U.S. Department of Defense Advanced Research Projects Agency (ARPA)[3] to head both its Command and Control Research division and its Behavioral Sciences division. Command and Control Research was soon renamed the Information Processing Techniques Office (IPTO). Licklider brought with him not only his ideas about time sharing and man-computer symbiosis; he also attracted many of the top computer scientists of the era to ARPA. He called this tight-knit group of scientists the Intergalactic Computer Network, an inside joke reflecting his most significant ideas of a globally connected computer network.

[3] In 1972, ARPA was somewhat unnecessarily renamed Defense Advanced Research Projects Agency, or DARPA.

Although Licklider stayed at IPTO only until 1964, his ideas were inseminated in the Intergalactic Computer Network. These scientists became some of the key figures in the development of the ARPANET.

An Early Vision of the Web

Licklider's early thoughts about man-computer symbiosis were influenced by those of another visionary: Vannevar Bush. Bush conceptualized a machine he called a "memex," which could be used to augment the cognitive process.

Bush published his thoughts about the memex in 1945 in an article called "As We Might Think."[4] The memex Bush envisioned would be used to retrieve information stored on microfilm: "A memex is a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory. It consists of a desk... On the top are slanting translucent screens, on which material can be projected... There is a keyboard, and sets of buttons and levers... As he [the user] has several projection positions, he can leave one item in position while he calls up another. He can add marginal notes and comments..."

What is so forward thinking is not the information-retrieval mechanism, but a proposed mechanism for linking information being called up, tying multiple pieces of information together: "When the user is building a trail, he names it, inserts it in his code book, and taps it out on his keyboard. Before him are the two items to be joined, projected onto adjacent viewing positions... The user taps a single key, and the items are permanently joined... Thereafter, at any time, when one of these items is in view, the other can be instantly recalled... Moreover, when numerous items have been thus joined together to form a trail, they can be viewed in turn, rapidly or slowly... It is exactly as though the physical items had been gathered together to form a new book. It is more than this, for any item can be joined into numerous trails."

Thus in 1945, and within the limitations the technology of the time, Vannevar Bush foresaw the information-linking capabilities of hypertext and the information-retrieval capabilities of the World Wide Web.


[4] Vannevar Bush, "As We Might Think," The Atlantic Monthly, July 1945.




OSPF and IS-IS(c) Choosing an IGP for Large-Scale Networks
OSPF and IS-IS: Choosing an IGP for Large-Scale Networks: Choosing an IGP for Large-Scale Networks
ISBN: 0321168798
EAN: 2147483647
Year: 2006
Pages: 111
Authors: Jeff Doyle

flylib.com © 2008-2017.
If you may any questions please contact us: flylib@qtcs.net