dotnet-core/release-notes/2.1/Preview/api-diff/preview1/2.1-preview1_System.Net.WebSockets.md

System.Net.WebSockets

 namespace System.Net.WebSockets {
+    [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
+    public struct ValueWebSocketReceiveResult {
+        public ValueWebSocketReceiveResult(int count, WebSocketMessageType messageType, bool endOfMessage);
+        public int Count { get; }
+        public bool EndOfMessage { get; }
+        public WebSocketMessageType MessageType { get; }
+    }
     public abstract class WebSocket : IDisposable {
+        public static WebSocket CreateFromStream(Stream stream, bool isServer, string subProtocol, TimeSpan keepAliveInterval, Memory<byte> buffer=default(Memory<byte>));
+        public virtual ValueTask<ValueWebSocketReceiveResult> ReceiveAsync(Memory<byte> buffer, CancellationToken cancellationToken);
+        public virtual Task SendAsync(ReadOnlyMemory<byte> buffer, WebSocketMessageType messageType, bool endOfMessage, CancellationToken cancellationToken);
     }
 }