The Valid Web

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					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

   XML/XHTML/HTML
   XML Schema
   XSL
The traditional web

   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

   View ply’s history data.

   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