2.5.1 ad:instance Header

An implementation can allow multiple directory services to be accessed via a single endpoint.<5> The ad:instance SOAP header, which is located in the http://schemas.microsoft.com/2008/1/ActiveDirectory XML namespace, is included in a SOAP request message to specify which directory service the request is intended for.

The content of the ad:instance header is the string literal "ldap:" followed by an integer (expressed as a string in base 10) that specifies the TCP port number of the desired directory service's LDAP interface.

In the following example, the requestor is asking that the operation (a WS-Transfer Get [WXFR]) that is specified in the SOAP message be performed against the directory service that listens on port 3268.

 <soapenv:Envelope>
   <soapenv:Header>
     <wsa:Action soapenv:mustUnderstand="1">
         http://schemas.xmlsoap.org/ws/2004/09/transfer/Get
     </wsa:Action>
     <ad:objectReferenceProperty>
         a492d5f2-18c3-4f93-87d8-09a8c66bb5e4
     </ad:objectReferenceProperty>
     <ad:instance>ldap:3268</ad:instance>
     <wsa:MessageID>
         urn:uuid:d3cf5d97-3e9d-4c1c-b7b7-f2893685ddea
     </wsa:MessageID>
     <wsa:ReplyTo>
       <wsa:Address>
           http://www.w3.org/2005/08/addressing/anonymous
       </wsa:Address>
     </wsa:ReplyTo>
     <wsa:To soapenv:mustUnderstand="1">
         net.tcp://server01.fabrikam.com:9389/ActiveDirectoryWebServices/Windows/Resource
     </wsa:To>
   </soapenv:Header>
   <soapenv:Body />
 </soapenv:Envelope>