#007FFF

public GraphClient(string tenantDomainName, string tenantId, string appPrincipalId, string servicePrincipalSymmetricKey)
{
 this.tenantDomainName = tenantDomainName;
 this.tenantId = tenantId;
 this.servicePrincipalSymmetricKey = servicePrincipalSymmetricKey;
 this.appPrincipalId = appPrincipalId;
 
 dataService = new DirectoryDataService(GetConnectionUri());
 dataService.SendingRequest += (sender, args) =>
 {
  var webRequest = ((HttpWebRequest)args.Request);
  webRequest.Headers.Add(HeaderName_Authorization, GetAuthorizationHeader());
  webRequest.Headers.Add(HeaderName_DataContractVersion, DataContractVersion);
  webRequest.Headers.Add(HeaderName_ClientRequestId, Guid.NewGuid().ToString());
 };
}

http://msdn.microsoft.com/en-us/library/windowsazure/dn151791.aspx
新增功能: http://blogs.msdn.com/b/aadgraphteam/archive/2013/09/18/enhancing-graph-api-queries-with-additional-odata-supported-queries.aspx