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180 lines
8.2 KiB
180 lines
8.2 KiB
<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta name="generator" content=
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"HTML Tidy for Mac OS X (vers 31 October 2006 - Apple Inc. build 13), see www.w3.org" />
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<title>
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Conversations - Ideaas about web architecture
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</title>
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<link rel="Stylesheet" href="di.css" type="text/css" />
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<meta http-equiv="Content-Type" content="text/html" />
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</head>
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<body bgcolor="#DDFFDD" text="#000000">
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<address>
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Tim Berners-Lee<br />
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Date: 1998, last change: $Date: 2009/08/27 21:38:06 $<br />
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Status: personal view only. Editing status: first draft.
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</address>
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<p>
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<a href="./">Up to Design Issues</a>
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</p>
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<hr />
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<h1>
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Conversations and state
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</h1>
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<p>
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See also: <a href="PaperTrail">Paper Trail</a> - presented as
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a a student project
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</p>
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<p>
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The basic model of the web is a world of information.
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Theoretically, a mapping between URIs and representations of
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the resources they identify, and experientially fro a person
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a space one can navigate.
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</p>
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<p>
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Interestingingly, trends at the leading edge of user
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interface development, and at the semantic web development
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both point to a world which uses a different model. Human
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interfaces are moving from screens to conversational mode.
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The semantic web, while very exciting when viewed as a
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</p>
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<p>
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Human user interfaces use more and more devices such as
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speech, gestures and so on, which are not screens. What is
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special about a screen? A screen with a window system
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presents a large amount of informatoin at the same time to a
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person. In practice, more or less everything which a person
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is concentrting on at one time can be presented in its
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current state. When the number of pixels on a screen broke
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through a certain threshold (roughly the 640x320 VGA limit)
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this led to the development of direct manipulation interface
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metaphors: folders one could open, and drag and drop. The
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essential things about this is that the computer is at every
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instant presenting the current state, whether it or the human
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is manipulating it. The communication betwen personand
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machine is in terms of the mutual manipulation of a shared
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state. The web was intended to extend that form of
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communication by mutual manipulation of a shared state to
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remote human-human interaction. While the tools and protocols
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have their limitations (see UI) much of its effectiveness
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derived from this model. Because fundamental thing is a
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shared space of information, one can talk about navigation
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around within the space, and use all the primaval facilities
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that the human memory has for navigation.
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</p>
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<p>
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This is all very well, but it was not always so. When
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computer terminals had only 24 rows of 80 characters, even
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when they were addressable, there was a tendency for most
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jobs to use command line interafaces, for example when
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manipulating files and directories. The interface was
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conversational, in that the exchanges were small commands and
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responses. There was a shared abstract state, but it was
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imagined in the abstract by the person, and held in some
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unvisualized form by the computer. This too has itas
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advantages, in that the imagination of a person can well
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exceed (on a good day) the capacity of a screen in its
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ability to hold complex interrelated structures. The
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interesting thing is that now there is a tednedncy to use
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many devices which do not have the large screen. The screens
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on cellphones are currently so small that, while one can
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scale a web page down and adapt it to a small screen, this
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might be chosing simply the wrong interface metaphor. When
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the audio phone only is used, then the shared state becomes
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zero and the interface is completely conversational again.
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</p>
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<p>
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The characteristic of a conversation is the state is the set
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of utterances, or messages, which have been conveyed. This is
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differenet from a shared expression of a commonly agreed
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state. The <a href="PaperTrail.html">Paper Trail concept</a>
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links these two modesl in the Semantic Wee Semantic Web, by
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formally defining the overal agreed state as a function of
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messages to date. A service which allows a phone user to
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browse the web converts the other way: it conveys part of the
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the space of information by means of a conversation. It is is
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important for a number of reasons.
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</p>
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<ul>
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<li>It allows us to formalize the models of human-machine
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interface which are in fact conversational for many
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non-screen devices;
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</li>
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<li>It allows us to formalize social, for example commercial,
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transactions for which the paper trail is in fact th emost
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accurate model anyway;
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</li>
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<li>It provides us with tools we can use for formally
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analysing the infrastructure protocols such as HTTP which
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with which the information world is actually implemented in
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practice.
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</li>
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<li>The standardization of XML protocols has, with XML (and
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RDF), a richness in terms of marshalling data formats to
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build on, and, with xml-schemas xforms and rdfs, a richness
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to draw on in terms of languages for defining valid
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documents, but has no basis yet for defining with equivalent
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power the validity (and semantics) of a sequence of
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interrlated messages which are a protocol.
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</li>
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</ul>
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<p>
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It is not as though the web today itself perfectly matches
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the stateless model at all. The moment it was created as a
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basically stateles system, many web site designers took it as
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their challenge to get around this model in order to create a
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conversational interface -- and many still do Our concerns
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about privacy stem largel;y from the knowledge that our
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"reading" of documents is in fact done by a series of
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protocols which leave a trace. The P3P project involves
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quantifying the information transfer which actually takes
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place. Our handling of HTML forms is getting more complex,
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and a form itself, becomes, on many sites, the definition os
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a protocol - a set of valid sequences of information
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actions..
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</p>
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<p>
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This was written as a note to accompany a talk to the W3C
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Advisory Committee of November 2000. At such times, we
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discuss the status of existing work and look ahead to feel
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the direction in which we will need to move in the future.
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Often, we notice that Web technology is now entering a field
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new to the Web but old of itself. In these cases, we can view
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the process we need to go through either has extending web
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technology into this field, or of <em>Webizing</em> the
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field. This has happened, more or less, to hypertext to SGML,
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and is heppending to knowledge representation. Now an
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interesting field is teh formal specification of protocols.
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There is much out there to build on, but is has not been
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applied yet to the exchange of XML documents conveying RDF
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graphs. However, it seems to be a relevant direction in which
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to look when predicting where the leading edge, and therefore
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the Consortium, should be in a few year's time.
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</p>
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<p>
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@@ - already web privacy concerns come from in fact it being
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a conversation -- there is implict state. A
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</p>
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<p>
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@@ Reasons for formalizaing protcols a la Paper Trail.: uses
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concepts of validation and will be able to resuse tools -
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extends semnatics of documnets to semnatics of conversaions.
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- Creates a formal basis for defining conversaionsal systems
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of all kinds, including indirctly human language oriented
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systems.
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</p>
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<p>
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@@ Machine-machines and human-human convergence
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</p>
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<p>
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Originally written 2000/11
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</p>
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<hr />
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<p>
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<a href="Overview.html">Up to Design Issues</a>
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</p>
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<p>
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<a href="../People/Berners-Lee">Tim BL</a>
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</p>
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</body>
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</html>
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