wcf - データテーブルではなくデータセットを取得しようとすると WCF エラーが発生する

Question

2 つのメソッドを持つ wcf basicHttpBinding サービスがあります。方法 1 は、データセット内の 2 つのデータ テーブルを返す oracle パッケージ ストアド プロシージャを実行します。これはうまくいきます。

方法 2 は、単純な select ステートメントを含む (単一の) テーブルを返します。これは例外 Why ? で失敗します。

System.ServiceModel.CommunicationException was caught
  Message=An error occurred while receiving the HTTP response to http://localhost:10500/WcfOracle.svc. This could be due to the service endpoint binding not using the HTTP protocol. This could also be due to an HTTP request context being aborted by the server (possibly due to the service shutting down). See server logs for more details.
  Source=mscorlib
  StackTrace:
    Server stack trace: 
       at System.ServiceModel.Channels.HttpChannelUtilities.ProcessGetResponseWebException(WebException webException, HttpWebRequest request, HttpAbortReason abortReason)
       at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
       at System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
       at System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
       at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
       at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs)
       at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
       at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
    Exception rethrown at [0]: 
       at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
       at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
       at svcOracleTestRig.wcfOracle.IWcfOracle.Select(String stmt, Boolean LeaveConnectionOpen)
       at svcOracleTestRig.wcfOracle.WcfOracleClient.Select(String stmt, Boolean LeaveConnectionOpen) in D:\iWorx-dev-v1\WCF4\svcOracle\svcOracleTestRig\Service References\wcfOracle\Reference.cs:line 180
       at svcOracleTestRig.Form1.button2_Click(Object sender, EventArgs e) in D:\iWorx-dev-v1\WCF4\svcOracle\svcOracleTestRig\Form1.cs:line 98
  InnerException: System.Net.WebException
       Message=The underlying connection was closed: An unexpected error occurred on a receive.
       Source=System
       StackTrace:
            at System.Net.HttpWebRequest.GetResponse()
            at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan timeout)
       InnerException: System.IO.IOException
            Message=Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
            Source=System
            StackTrace:
                 at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
                 at System.Net.PooledStream.Read(Byte[] buffer, Int32 offset, Int32 size)
                 at System.Net.Connection.SyncRead(HttpWebRequest request, Boolean userRetrievedStream, Boolean probeRead)
            InnerException: System.Net.Sockets.SocketException
                 Message=An existing connection was forcibly closed by the remote host
                 Source=System
                 ErrorCode=10054
                 NativeErrorCode=10054
                 StackTrace:
                      at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
                      at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
                 InnerException: