diff --git a/src/dotnet/FileSystemHost.cs b/src/dotnet/FileSystemHost.cs
index ace67292..3f8bd2fb 100644
--- a/src/dotnet/FileSystemHost.cs
+++ b/src/dotnet/FileSystemHost.cs
@@ -381,6 +381,89 @@ namespace Fsp
         {
             return Api.GetVersion();
         }
+        /// <summary>
+        /// Returns a RequestHint to reference the current operation asynchronously.
+        /// </summary>
+        public UInt64 GetOperationRequestHint()
+        {
+            return Api.FspFileSystemGetOperationRequestHint();
+        }
+        /// <summary>
+        /// Asynchronously complete a Write operation.
+        /// </summary>
+        /// <param name="RequestHint">
+        /// A reference to the operation to complete.
+        /// </param>
+        /// <param name="Status">
+        /// STATUS_SUCCESS or error code.
+        /// </param>
+        /// <param name="BytesTransferred">
+        /// The number of bytes written.
+        /// </param>
+        /// <param name="FileInfo">
+        /// Updated file information.
+        /// </param>
+        public void SendWriteResponse(UInt64 RequestHint, UInt32 Status, UInt32 BytesTransferred, ref FileInfo FileInfo)
+        {
+            var Response = new FspFsctlTransactRsp()
+            {
+                Size = 128,
+                Kind = (UInt32) FspFsctlTransact.WriteKind,
+                Hint = RequestHint
+            };
+            Response.IoStatus.Information = BytesTransferred;
+            Response.IoStatus.Status = Status;
+            Response.WriteFileInfo = FileInfo;
+            Api.FspFileSystemSendResponse(_FileSystemPtr, ref Response);
+        }
+        /// <summary>
+        /// Asynchronously complete a Read operation.
+        /// </summary>
+        /// <param name="RequestHint">
+        /// A reference to the operation to complete.
+        /// </param>
+        /// <param name="Status">
+        /// STATUS_SUCCESS or error code.
+        /// </param>
+        /// <param name="BytesTransferred">
+        /// Number of bytes read.
+        /// </param>
+        public void SendReadResponse(UInt64 RequestHint, UInt32 Status, UInt32 BytesTransferred)
+        {
+            var Response = new FspFsctlTransactRsp()
+            {
+                Size = 128,
+                Kind = (UInt32) FspFsctlTransact.ReadKind,
+                Hint = RequestHint
+            };
+            Response.IoStatus.Information = BytesTransferred;
+            Response.IoStatus.Status = Status;
+            Api.FspFileSystemSendResponse(_FileSystemPtr, ref Response);
+        }
+        /// <summary>
+        /// Asynchronously complete a ReadDirectory operation.
+        /// </summary>
+        /// <param name="RequestHint">
+        /// A reference to the operation to complete.
+        /// </param>
+        /// <param name="Status">
+        /// STATUS_SUCCESS or error code.
+        /// </param>
+        /// <param name="BytesTransferred">
+        /// Number of bytes read.
+        /// </param>
+        public void SendReadDirectoryResponse(UInt64 RequestHint, UInt32 Status, UInt32 BytesTransferred)
+        {
+            var Response = new FspFsctlTransactRsp()
+            {
+                Size = 128,
+                Kind = (UInt32) FspFsctlTransact.QueryDirectoryKind,
+                Hint = RequestHint
+            };
+            Response.IoStatus.Information = BytesTransferred;
+            Response.IoStatus.Status = Status;
+            Api.FspFileSystemSendResponse(_FileSystemPtr, ref Response);
+        }
 
         /* FSP_FILE_SYSTEM_INTERFACE */
         private static Byte[] ByteBufferNotNull = new Byte[0];
diff --git a/src/dotnet/Interop.cs b/src/dotnet/Interop.cs
index a6b41ddf..08079c92 100644
--- a/src/dotnet/Interop.cs
+++ b/src/dotnet/Interop.cs
@@ -354,6 +354,65 @@ namespace Fsp.Interop
         public IntPtr Information;
     }
 
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct IoStatus
+    {
+        internal UInt32 Information;
+        internal UInt32 Status;
+    }
+
+    internal enum FspFsctlTransact
+    {
+        ReadKind = 5,
+        WriteKind = 6,
+        QueryDirectoryKind = 14
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    internal struct FspFsctlTransactReq
+    {
+        [FieldOffset(0)]
+        internal UInt16 Version;
+        [FieldOffset(2)]
+        internal UInt16 Size;
+        [FieldOffset(4)]
+        internal UInt32 Kind;
+        [FieldOffset(8)]
+        internal UInt64 Hint;
+
+        [FieldOffset(0)]
+        internal unsafe fixed Byte Padding[88];
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    internal struct FspFsctlTransactRsp
+    {
+        [FieldOffset(0)]
+        internal UInt16 Version;
+        [FieldOffset(2)]
+        internal UInt16 Size;
+        [FieldOffset(4)]
+        internal UInt32 Kind;
+        [FieldOffset(8)]
+        internal UInt64 Hint;
+
+        [FieldOffset(16)]
+        internal IoStatus IoStatus;
+
+        [FieldOffset(24)]
+        internal FileInfo WriteFileInfo;
+
+        [FieldOffset(0)]
+        internal unsafe fixed Byte Padding[128];
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    internal unsafe struct FspFileSystemOperationContext
+    {
+        internal FspFsctlTransactReq *Request;
+        internal FspFsctlTransactRsp *Response;
+    }
+
     [StructLayout(LayoutKind.Sequential)]
     internal struct FileSystemInterface
     {
@@ -662,6 +721,12 @@ namespace Fsp.Interop
             internal delegate Int32 FspFileSystemStopDispatcher(
                 IntPtr FileSystem);
             [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+            internal delegate void FspFileSystemSendResponse(
+                IntPtr FileSystem,
+                ref FspFsctlTransactRsp Response);
+            [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+            internal delegate ref FspFileSystemOperationContext FspFileSystemGetOperationContext();
+            [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
             internal delegate IntPtr FspFileSystemMountPointF(
                 IntPtr FileSystem);
             [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
@@ -846,6 +911,8 @@ namespace Fsp.Interop
         internal static Proto.FspFileSystemRemoveMountPoint FspFileSystemRemoveMountPoint;
         internal static Proto.FspFileSystemStartDispatcher FspFileSystemStartDispatcher;
         internal static Proto.FspFileSystemStopDispatcher FspFileSystemStopDispatcher;
+        internal static Proto.FspFileSystemSendResponse FspFileSystemSendResponse;
+        internal static Proto.FspFileSystemGetOperationContext FspFileSystemGetOperationContext;
         internal static Proto.FspFileSystemMountPointF FspFileSystemMountPoint;
         internal static Proto.FspFileSystemSetOperationGuardStrategyF FspFileSystemSetOperationGuardStrategy;
         internal static Proto.FspFileSystemSetDebugLogF FspFileSystemSetDebugLog;
@@ -892,6 +959,12 @@ namespace Fsp.Interop
             else
                 return _FspFileSystemSetMountPointEx(FileSystem, MountPoint, IntPtr.Zero);
         }
+        internal static unsafe UInt64 FspFileSystemGetOperationRequestHint()
+        {
+            FspFileSystemOperationContext Context = FspFileSystemGetOperationContext();
+            FspFsctlTransactReq Request = *Context.Request;
+            return Request.Hint;
+        }
         internal static unsafe Boolean FspFileSystemAddDirInfo(
             ref DirInfo DirInfo,
             IntPtr Buffer,
@@ -1240,6 +1313,8 @@ namespace Fsp.Interop
             FspFileSystemRemoveMountPoint = GetEntryPoint<Proto.FspFileSystemRemoveMountPoint>(Module);
             FspFileSystemStartDispatcher = GetEntryPoint<Proto.FspFileSystemStartDispatcher>(Module);
             FspFileSystemStopDispatcher = GetEntryPoint<Proto.FspFileSystemStopDispatcher>(Module);
+            FspFileSystemSendResponse = GetEntryPoint<Proto.FspFileSystemSendResponse>(Module);
+            FspFileSystemGetOperationContext = GetEntryPoint<Proto.FspFileSystemGetOperationContext>(Module);
             FspFileSystemMountPoint = GetEntryPoint<Proto.FspFileSystemMountPointF>(Module);
             FspFileSystemSetOperationGuardStrategy = GetEntryPoint<Proto.FspFileSystemSetOperationGuardStrategyF>(Module);
             FspFileSystemSetDebugLog = GetEntryPoint<Proto.FspFileSystemSetDebugLogF>(Module);