1. An XML/XSL Infrastructure for Temporal Management of Web Documents
The Valid Web
An XML/XSL Infrastructure for Temporal Management of Web Documents

2. 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.

3. 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.

4. The purpose
Support time selection on the documents of the world wide web.

5. Some technologies we use
XML/XHTML/HTML
XML Schema
XSL

6. The traditional web
There are no valid time information. We cannot access contents in the web page according to specific time.

7. The valid web
The contents in the world wide web could be accessed selectively according to the valid time (interesting time).

8. HTML/XHTML documents
In order to support valid time web, all providers need to do is adding <valid> tag to original HTML/XHTML documents.

9. 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.

10. XML/XSL XSL can support conditional operation on XML documents.
XSL is responsible for dynamic filtering the XML documents according to the valid time.

11. How XSL operate

12. XSL example This example provided by Pada ( http://www.pada.biz/ )
Pada use XML/XSL architecture to support database of articles.

13. 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=“*” />
</Schema>

14. Valid tag example <valid>
<validity from=“ ” to=“ ” />
<validity from=“ ” to=“ ” />
This is content valid from 1980 ~ but also 1995 ~ 2000
</valid>

15. XSL document for filtering
<xsl:template match=“valid”>
<xsl:choose>
<xsl:when test=“validity()”>
<xsl:copy>
<xsl:apply-templates />
</xsl:copy>
</xsl:when>
<xsl:otherwise>
not in valid time
</xsl:otherwise>
</xsl:choose>

16. A simple example
View ply’s history data.

17. 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

18. 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

19. Thanks