2.8.2 Returning Trust Scores

The Trust Scoring is available from the Trust PDP component. As PDPs use XACML protocol, which natively does not have ability to convey anything else than Permit or Deny decision and associated obligations, we profile the second level XACML <StatusCode> to carry the ranking information: the Value XML attribute holds a URN prefix, identifying the trust ranking scheme, followed by actual raning in the syntax specified by the scheme.

Example

  <StatusCode Value="urn:oasis:names:tc:xacml:1.0:status:ok">
    <StatusCode Value="urn:tas3:trust:ctl1:ranking:avgfeedback=0.960922">
      <StatusCode Value="urn:tas3:trust:ctl1:ranking:oct=0.711221"/>
    </StatusCode>
  </StatusCode>

The status codes are extracted by the Discovery Service and packaged as additional EPR metadata when returned to the caller:

  <a:EndpointReference
      xmlns:a="http://www.w3.org/2005/08/addressing"
      xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
      notOnOrAfter="2037-01-05T23:03:59.001Z"
      wsu:Id="EPRID92lFPo3ZNEt_3rHtJFoU">
    <a:Address>
      http://141.26.143.22:8080/matching-simple/services/SimpleResource
    </a:Address>
    <a:Metadata>
      <sbf:Framework
          xmlns:sbf="urn:liberty:sb"
          version="2.0"/>
      <di:Abstract xmlns:di="urn:liberty:disco:2006-08">Test</>
      <di:ProviderID xmlns:di="urn:liberty:disco:2006-08">
        http://141.26.143.22:8080/wspdemosp3.xml
      </di:ProviderID>
      <di:ServiceType xmlns:di="urn:liberty:disco:2006-08">urn:tas3:matchingservice</>
      <tas3:Trust vers="ctl1">
        <tas3:TrustRanking metric="avgfeedback" val="0.960922"/>
        <tas3:TrustRanking metric="oct" val="0.711221"/>
      </tas3:Trust>
    </a:Metadata>
  </a:EndpointReference>