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150 lines
6.1 KiB
150 lines
6.1 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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The Semantic Web Clipboard - Design Issues
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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=
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"text/html; charset=us-ascii" />
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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: 2004/01, last change: $Date: 2004/01/15 19:47:08
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$<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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Semantic Clipboard
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</h1>
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<p>
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One way of looking at the Semantic Web is a breaking down of
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barriers between applications. An example I have often quoted
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is that I would like to be able to drag a photo album onto a
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calenar application and see the photos on my calendar.
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</p>
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<p>
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What would this actually take?
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</p>
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<p>
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The intersting case that the calendar application and the
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phto album application were written indepedently, without
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this case in mind. Suppose they were, though written to be
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semantic-web aware. So they will have ontologies for the
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things they deal with (photos, events resepctively in this
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case.) They will store their data, or at least a copy of it,
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in RDF.
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</p>
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<p>
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The clipboard, which stores things which we copy and paste,
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is a complex thing. It doesn't always hold the value of
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something clipped, it sometimes just remembers where it was
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clipped from. There is a form of negotiation between the
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source and destination about the format for the data to be
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transferred. This is why you can copy from text from a web
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page (which is structured hypertext) into a plain text
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message. There is a negotiation, and the source and
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destinatio can both use a plain text clipboad type.
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</p>
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<p>
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In this example, we can imagine there being a Semantic Web
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clipboard type. The data is basically transferred as an RDF
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graph. But that isn't the end of it. Different applications
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understand different vocabularies (ontologies). So a semantic
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web clipboard (or the application) does more than just
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transfer data. It arranges to convert it into a useful form.
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</p>
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<p>
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When you drag something onto the calendar application, it may
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be expecting events. It may be able to use anything which has
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at least a start datetime and and a description. the typical
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vocabulary here is iCalendar-like, such as @@@@. The photo
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has a date of creation and may have a form of description. It
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will typically have technical details of the exposure. The
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typical vocabulary here is EXIF-like, such as @@@@.
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</p>
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<p>
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RDF Interest group people have looked at conversion tools. At
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MIT we've had fun converting things like this deliberately.
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How can it happen in this example?
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</p>
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<p>
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Somehow, the user must authorize conversion rules to be
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available to the semantic web clipboard, so that the
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convertion can be done. The clipboard indexes the rules,
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knows what form of information is needed by the application
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through some kind of registration, and knows what sort of
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information is available on the clipboard.
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</p>
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<p>
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Typically, these things are customized. I might like the
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description of the event of a phtograph being taken to have a
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list of the people in the shot, if it is known; others might
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just want the brief "Pic!".
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</p>
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<h2>
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Sources and organization of rules
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</h2>
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<p>
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An advanced user who uses some kind of tool to generate a
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rule, as users do today for email filtering. The user is a
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third party. Third party rule sources may include system
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administrators.
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</p>
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<p>
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The source could be the creator of one or other program:
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calendar or photo album. One might exect the program which is
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released second to come with rules for connection to other
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things already released. In this case, there is some order in
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that the rules link applictions in a directed way. If in
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laterreleases both applications offer rules to convert the
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same way, then a choice has to be made, just as one sometiems
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has to chose whether to trust the provider of the printer or
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the provider of the operating system when installing a
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printer driver.
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</p>
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<p>
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Users will have to track the trust worthiness of many
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different sources of data, but these rules will give a lot
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back for something quite small.
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</p>
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<p>
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There is a form of entropy which increases as these rules are
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used. Some rules may be reversable, but typically they are
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not. You can't turn every event back into a picture, and you
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can't event turn a picture taking event back into the picture
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as you have lost some data. An event is in this example a
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more generic thing than a picture. One might assume that the
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system will in general try to reduce this information loss.
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This will involve trading at the highest level, or usingthe
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fewest rules. The sense of specificity might therefore form
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an organizing technique. This is similar to a form of pecking
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order between a rich text clipboard and a plain text
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clipboard: is applications can use the more sophisticated,
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less information is lost.
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</p>
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<h2>
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Conclusion
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</h2>
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<p>
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The Semantic Web clipboard might be a nifty hack in the short
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term, might be a mainstay of desktop interoperability in the
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future. From the reseacrh point of view, the rule management
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involved is a miniature version of the Semantic Web rule
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indexing search engine.
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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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