The problem

• XML document may become too large to parse or transfer
• Need for a mechanism to isolate a fragment of an XML document
• One also need to provide fragment metadata
• And a way to combine them

What does it looks like

Technical choices

• The fragment body is a well-balanced chunk of the original XML document
• The fragment context is expressed as well-formed XML
• Flexibility in the expressiveness of the fragment context is required
• An XML packaging is suggested, but stay non-normative

The fragment context

• Placeholder for pointers to subsets, parent, and the fragment in-situ
• Is an XML tree containing at least all the ancestors nodes of the fragment
• Has a special "fragbody" element expressing the location of the fragment in that tree
• Can be enriched by others nodes like fragment siblings and ancestors sibling
• Attributes are allowed, but not text content

Example of a fragment context

<f:fcs xmlns:f="http://www.w3.org/XML/Fragment/1.0"
       extref="http://www.oasis-open.org/docbook/docbook/3.0/docbook.dtd"
       parentref="http://www.acme.com/~me/mydocs/mybook.xml"
       xmlns="http://www.oasis-open.org/docbook/DocbookSchema">
  <book>
    <part>
      <chapter>
        <sect1/>
        <sect1>
          <orderedlist numeration="arabic">
   	 <listitem/>
   	 <f:fragbody fragbodyref="http://www.acme.com/~me/mydocs/myfrag.xml"/>
          </orderedlist>
        </sect1>
      </chapter>
    </part>
  </book>
</f:fcs>

Fragment context tricks

• Be careful with entities references, you may get well-formedness errors
• It can be used to provide an Index to a large document, c.f. example C.3.
• The sourcelocn used XPointer, but the syntax will change

The packaging syntax

Defined in a non -normative appendix

<p:package xmlns:p="http://www.w3.org/XML/Package/1.0"
	   xmlns:f="http://www.w3.org/XML/Fragment/1.0"
	   xmlns="{the default namespace in effect at the start
		   of the fragment body in the parent document}">
  <f:fcs {the ref attributes on the fcs tag}>
   {the content of the fcs with no namespace prefixes
     necessary except that on the <f:fragbody/> element}
  </f:fcs>

  <p:body>
  {the fragment body with no namespace prefixes necessary}
  </p:body>

</p:package>

Packaging tricks

• Again, be careful with entities references.
• Other metadata can be added too, fcs is just one of them
• It will be overriden by the work from the XML Packaging WG.

  Future

  • Proposed Req before WWW8
  • IBM talking about implementation, but they are blocked by XPointer
  • Schemas will help w.r.t. the current subsets problem
  • Most participants in Fragment will join XML Packaging WG
  • A revision will have to be done when XLink will support multiple links on one elem.