ce of calls for obtaining
 a client authentication context object, and then using it to secure 
 a request.
 <ol>
 <li>AuthConfigProvider provider;
 <li>ClientAuthConfig config = provider.getClientAuthConfig(layer,appID,cbh);
 <li>String authContextID = config.getAuthContextID(messageInfo);
 <li>ClientAuthContext context = config.getAuthContext(authContextID,subject,properties);
 <li>context.secureRequest(messageInfo,subject);
 </ol>

 <p> Every implementation of this interface must offer a public,
 two arg