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Presentation to L3D on XML by Gerry Stahl and Aaron Martin March 15, 2000
Why XML? ·
open standard ·
human-readable ·
as simple as HTML ·
extensible – can define your own DTD ·
application-independent – good for interoperability exchange of
data What is it used for? ·
as metadata to tag data on web ·
for data interchange ·
for internal structure (e.g., Microsoft PowerPoint slides on Web) Why use it at L3D
? To reseed info spaces. WebGuide:
a Java applet (above) showing the threads of discussion notes with an HTML
frame (below) displaying the content of one note. WebGuide – Gulch version for an environmental middle school class
JIME: The hierarchy of threads in context of a journal article under review
JIME: the detail of one note DynaClass:
a note with discussion Sources: a bibliography entry DynaGloss: a glossary definition Reseeding dispersed ideas into one information space Data can be exported using code internal to the exporting application or by independent code that parses an HTML output file generated by the application. The exported XML can be formatted recursively (one note can contain others) or non-recursively (with links from one note to another using XLINK). A recursive format is easier to display using XSL; a non-recursive format is a more faithful representation for importing back into an application like WebGuide that allows multiple links in and out of notes.
data for demo in Dynasites at: http://seed.cs.colorado.edu/dynaClass.displayNode.fcgi$URLinc=1&node=Node41&doc=DLC99
demo of data export at: Open
architecture
<?xml
version="1.0"?> <!--
WEBGUIDE version 1.2 XML RECURSIVE data structure --> <!--
created 5/25/99 by Gerry Stahl --> <!--
following
is the Document Type Definition: --> <!DOCTYPE
DATASET[ <!--
DATASET is
a collection of NOTES from a threaded discussion database--> <!--
a DATASET includes
the root NOTE of the threaded discussion --> <!ELEMENT
DATASET (DESCRIPTION?,
COMMENT?, NOTE) > <!ATTLIST
DATASET SYSTEM
CDATA #REQUIRED CREATOR
CDATA #IMPLIED DATE
CDATA #REQUIRED XML_VERSION
CDATA "1.0"
<!--
NOTE
is a tree of information in a DATASET, recursively containing subtrees--> <!--
a NOTE
may contain as children the root NOTEs of its subtrees--> <!--
if a NOTE
has multiple parents, then it appears as multiple NOTEs with the same NID
--> <!ELEMENT
NOTE
(TITLE, CONTENT, NOTES*) > <!ATTLIST
NOTE NID ID #REQUIRED
NOTE_KIND
CDATA "Statement"
AUTHOR
CDATA "Anonymous"
CREATED
CDATA #REQUIRED LINK_TYPE
CDATA "Re" PERSPECTIVE
CDATA #IMPLIED ADDITIONAL1
CDATA #IMPLIED ADDITIONAL2
CDATA #IMPLIED <!ELEMENT
DESCRIPTION
#PCDATA > <!ELEMENT
COMMENT
#PCDATA > <!ELEMENT
TITLE
#PCDATA > <!ELEMENT
CONTENT
#PCDATA > <!--
some sample data for testing --> <DATASET
SYSTEM="WebGuide"
CREATOR="GerryStahl"
DATE="29/09/1999"
XML_VERSION="1.0" >
<DESCRIPTION>"Research '99
WebGuide"</DESCRIPTION>
<COMMENT>="interesting ideas about
WebGuide"</COMMENT>
<NOTE KIND="Statement"
AUTHOR="Anonymous"
CREATED="05/25/1999"
TYPE="Re" PERSPECTIVE="Gerry's perspective" >
<TITLE>"Root note"</TITLE>
<CONTENT>"This is the root note"</CONTENT>
<NOTE KIND="Discussion"
AUTHOR="Gerry"
CREATED="05/25/1999"
TYPE="Re" PERSPECTIVE="Gerry's perspective" >
<TITLE>"A"</TITLE>
<CONTENT>"note A is the first real
note"</CONTENT>
<NOTE KIND="Comment"
AUTHOR="Gerry"
CREATED="05/25/1999"
TYPE="Re" PERSPECTIVE="Gerry's perspective" >
<TITLE>"B"</TITLE>
</NOTE>
</NOTE>
</NOTE> </DATASET> XML
displayed in IE 5.0 with default style sheet
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