VOEvent RDF Notes

RDF Generation

1st attempts - manual RDF generation from VOEvent xml packet

• copy / paste with W3C RDF validator - http://www.w3.org/RDF/Validator
• manual attempt now validating - attached as lasco_correct1.rdf
• now streamline RDF - standardize which string information is left as property element string content and which is stored as attributes:
  1. voe:ivorn and voe:role are left as property elements - cannot be property attributes since VOEvent includes attribute rdf:ParseType to designate as Resource
  2. basically, any property element with rdf:parseType="Resource" attribute must have child elements to contain other string values, even if those values were attributes of the original element in XML
  3. When is rdf:parseType="Resource" mandatory? Good rule of thumb: if a property element contains two or more child elements, and
     • at least one child element is likely to be lengthy (such as ) OR
     • any child element requires its own attribute
  4. ISOTime has been made an attribute of the TimeInterval element to mirror and under SpectralInterval
  5. It looks like an element that is not declared rdf:parseType="Resource" (such as AstroCoordArea) may have a child element or a great-grandchild element with string content, but not a grandchild with string content - see W3C RDF / XML syntax. For instance,

          <stc:AstroCoordArea  stc:coord_system_id="ICRS">
              <stc:RedshiftInterval>12</stc:RedshiftInterval>
              <stc:TimeInterval><stc:StartTime><stc:ISOTime>2005-12-06T23:24:05</stc:ISOTime></stc:StartTime></stc:TimeInterval>
              <stc:SpectralInterval stc:unit="nm" stc:LoLimit="430" stc:HiLimit="750"/>
          </stc:AstroCoordArea>

and

     <stc:AstroCoordArea  stc:coord_system_id="ICRS">
         <stc:RedshiftInterval><stc:HiLimit><stc:LoLimit>12</stc:LoLimit></stc:HiLimit></stc:RedshiftInterval>
         <stc:TimeInterval><stc:StartTime><stc:ISOTime>2005-12-06T23:24:05</stc:ISOTime></stc:StartTime></stc:TimeInterval>
         <stc:SpectralInterval stc:unit="nm" stc:LoLimit="430" stc:HiLimit="750"/>
     </stc:AstroCoordArea>

are OK, but

     <stc:AstroCoordArea  stc:coord_system_id="ICRS">
         <stc:RedshiftInterval><stc:HiLimit>12</stc:HiLimit></stc:RedshiftInterval>
         <stc:TimeInterval><stc:StartTime><stc:ISOTime>2005-12-06T23:24:05</stc:ISOTime></stc:StartTime></stc:TimeInterval>
         <stc:SpectralInterval stc:unit="nm" stc:LoLimit="430" stc:HiLimit="750"/>
     </stc:AstroCoordArea>

is not. Don't really understand why yet! W3C RDF / XML syntax section 2.11 "Omitting blank nodes" has more information.

-- ElizabethAuden - 25 Jan 2007