Transcript Document

The Valid Web
An XML/XSL Infrastructure for
Temporal Management of Web
Documents
Authors and source

Fabio Grandi and Federica Mandreoli,
CSITE-CNR, Dip. Di Elettronica,
Informatica e Sistemistica, Universita
di Bologna

Advances in Information Systems
conference, ADVIS 2000.
World wide web

World wide web is the biggest and
continually growing database.

Some researchers studying in the field
of TDBs have changed their interesting
from relational database to Internet.
The purpose

Support time selection on the
documents of the world wide web.
Some technologies we use
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XML/XHTML/HTML
XML Schema
XSL
The traditional web
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There are no valid time information.
We cannot access contents in the web
page according to specific time.
The valid web

The contents in the world wide web
could be accessed selectively
according to the valid time (interesting
time).
HTML/XHTML documents

In order to support valid time web, all
providers need to do is adding <valid>
tag to original HTML/XHTML
documents.
XML schema

XML schema is more flexible and
extensible than DTD ( Document Type
Definition ).

We use XML Schema to define new
valid, and related children tags.
XML/XSL

XSL can support conditional operation
on XML documents.

XSL is responsible for dynamic filtering
the XML documents according to the
valid time.
How XSL operate
XSL example

This example provided by Pada
( http://www.pada.biz/ )

Pada use XML/XSL architecture to
support database of articles.
Valid tag definition
<Schema>
<AttributeType name=“from” required=“yes” dt:type=“date” />
<AttributeType name=“to” required=“yes” dt:type=“date” />
<ElementType name=“validity”>
<attribute type=“from” minOccurs=“1” maxOccurs=“1” />
<attribute type=“to” minOccurs=“1” maxOccurs=“1” />
</ElementType>
<ElementType name=“valid” content=“mixed”>
<element type=“validity” minOccurs=“1” maxOccurs=“*” />
</ElementType>
</Schema>
Valid tag example
<valid>
<validity from=“1980-01-01” to=“1985-12-31” />
<validity from=“1995-01-01” to=“2000-12-31” />
This is content valid from 1980 ~ 1985 but
also 1995 ~ 2000
</valid>
XSL document for filtering
<xsl:template match=“valid”>
<xsl:choose>
<xsl:when test=“validity()”>
<xsl:copy>
<xsl:apply-templates
select=“@*|*|comment()|pi()|text()” />
</xsl:copy>
</xsl:when>
<xsl:otherwise>
not in valid time
</xsl:otherwise>
</xsl:choose>
A simple example
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View ply’s history data.
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http://www.pada.biz/tdb/
討論

XML/XSL 的架構能夠與過去的 Web 文件
相容，而且 XSL parser 也已經被實作在
各大瀏覽器以及各主流的程式語言中，建
立此架構需要的代價也不高

若瀏覽器能夠支援 ( 只須很小的努力 )，
則可以在網際網路上完全實踐 time
selection
討論

即使瀏覽器不支援，也可以使用 cookie
和 server 端的程式，讓有此需要的網
站做 time selection
Thanks