Extension mechanism proposal for 12/14 phone vote

["Adams, Robert" <robert.adams@intel.com>]

Here is a description, text and schema for (what I believe) is the header
extension mechanism we discussed last week.  This is for the vote that is
scheduled for this Thursday's phone call.  This adds an <extension> element
to DocumentReference, Manifest and ebXMLHeader.  The contents of this
element must be namespace qualified and it has a "mustUnderstand" attribute
that has a default value of "true".

== Add section 7.7.2.3 (missing?)
== Add section 7.7.2.4
7.7.2.4 Extension
The Extension element is optional and may occur multiple times within the
ebXMLHeader element. It contains extra information pertaining to the header
or the document as a whole. Examples could be signature information on the
Header or Manifest elements or extra routing or error information.  
The Extension element has an attribute "mustUnderstand" which can have the
values "true" (or "1") and "false" (or "0"). A receiving agent who receives
a message with an Extension element who's "mustUnderstand" attribute's value
is "true", and the receiver does not know how to process the content, the
receiver will return an error.  If the value of the "mustUnderstand" element
is "false", then the receiver may skip over the contents of this element if
the receiver does not know how to process the contents.
If the "mustUnderstand" attribute is not present, the value is presumed to
be "true".
The elements in the body of the Extension element must be XML namespace [XML
Namespace] qualified.
== Modify section 7.8
"consisting of zero or more DocumentReference elements." becomes "consisting
of zero or more DocumentReference elements followed by zero or more
extension elements".
Append to paragraph: "The extension elements contain additional information
that pertains to the whole manifest.  Refer to section 7.7.2.4 for a
detailed description of the Extension element.
== Add in section 7.8.1 (added "Extension" to send of list)
== Add section 7.8.1.4
7.8.1.4 Extension
The <strong>Extension</strong> element is optional and may occur multiple
times within the DocumentReference  element.  It contains extra information
pertaining to this particular document.  Examples could be signature or
certificate information for the document or additional description or
identification.  Refer to section 7.7.2.4 for a detailed explanation of the
Extension element.


===================DTD Fragments======================
<!ELEMENT xbXMLHeader (Manifest, Header, RoutingHeader, Extension*)>
...
<!ELEMENT Manifest (DocumentReference+, Extension*)>
...
<!ELEMENT DocumentReference (DocumentDescription?, DocumentLabel,
DocumentID, Extension*)>
...
<!-- this DTD does not enforce all of the constraints for "Extension".  The
content of the Extension
      element must be XML namespace qualified.  The default processing of
the content is "skip". -->
<!ELEMENT Extension (ANY)*>
<!ATTLIST Extension mustUnderstand CDATA #IMPLIED "true">
===================Schema Fragments===================
<element name="ebXMLHeader">
    <complextype content="elementOnly">
        <sequence>
            <element ref="Manifest"/>
            <element ref="Header"/>
            <element ref="RoutingHeader"/>
            <element ref="Extension" minOccurs="0" maxOccurs="unbounded"/>
        </sequence>
    </complextype>
</element
...
<element name="Manifest">
    <complexType>
        <sequence>
            <element ref="DocumentReference"
                    minOccurs="0" maxOccurs="unbounded"/>
            <element ref="Extension"
                    minOccurs="0" maxOccurs="unbounded/>
        </sequence>
    </complexType>
</element>
...
<element name="DocumentReference">
    <complexType>
        <sequence>
            <element ref="DocumentDescription"
                minOccurs="0" />
            <element ref="DocumentLabel" />
            <element ref="DocumentID" />
            <element ref="Extension"
                    minOccurs="0" maxOccurs="unbounded"/>
        </sequence>
    </complexType>
</element>
...
<!-- Elements contained in Extension must be namespace
    qualified.  If the namespace is not understood and the mustUnderstand
    attribute is set to true, then the contents of the
    DocumentReference should not be used. -->
<element name="Extension">
    <complexType>
        <sequence>
            <any namespace="##other" processContents="skip" />
        </sequence>
        <attribute name="mustUnderstand" type="boolean"
                use="optional" value="true" />
    </complexType>
</element>
=========================end of Fragments =========================

	Robert Adams
	mailto:Robert.Adams@intel.com
	MS JF3-212
	2111 NE 25th Ave
	Hillsboro, OR   97124    USA
	phone: +1.503.264.9424; cell: +1.503.709.3259; FAX: +1.503.264.3375