Creating a new Dictionary in a SOAP Envelope

Question

Pretty basic question, but I can't seem to find the answer anywhere.

How do you specify a new instance of a Dictionary<string, string> in SOAP? Basically I have this envelope (ommitted envelope top level tag for readability):

<soapenv:Body>
   <tem:LogInWithCredentials>      
       <tem:Request>             
       <ttf1:Password>password</ttf1:Password>         
       <ttf1:UserName>username</ttf1:UserName>
       <ttf1:RequestInfo></ttf1:RequestInfo>
      </tem:Request>      
   </tem:LogInWithCredentials>
</soapenv:Body>

RequestInfo is the property in question, but it's always null. I assumed that just the presence of the property in the envelope would be deserialized into an empty Dictionary<string, string>, however this is not the case.

Answer 1

As @flem says, the DataContractSerializer might provide the clues needed to answer this. Serializing an empty dictionary gives the following XML. Give that a try in your RequestInfo element and see if it works (I've not tested it myself).

<ArrayOfKeyValueOfstringstring 
    xmlns:i="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://schemas.microsoft.com/2003/10/Serialization/Arrays" />