chore(event): save unfinished work.

HandyIpc/Core/ConnectionExtensions.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -32,5 +33,31 @@ public static async Task<byte[]> InvokeAsync(this IConnection connection, byte[]
                 throw;
             }
         }
+
+        public static void Subscribe(this IConnection connection, Guid id, Func<byte[], byte[]> callback, CancellationToken token)
+        {
+            // TODO: Subscribe by id.
+            connection.Write(id.ToByteArray());
+            byte[] subscribeResult = connection.Read();
+            // Check result and retry.
+
+            Task.Run(() => connection.Loop(id, callback, token), token);
+        }
+
+        private static async Task Loop(this IConnection connection, Guid id, Func<byte[], byte[]> callback, CancellationToken token)
+        {
+            while (!token.IsCancellationRequested)
+            {
+                // Will blocked until accepted a notification.
+                byte[] input = await connection.ReadAsync(token);
+                byte[] output = callback(input);
+                await connection.WriteAsync(output, token);
+            }
+
+            // TODO: Unsubscribe by id.
+            await connection.WriteAsync(id.ToByteArray(), token);
+            byte[] unsubscribeResult = await connection.ReadAsync(token);
+            // Check result and retry.
+        }
     }
 }

HandyIpc/Core/Subscription.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace HandyIpc.Core
+{
+    public class Subscription
+    {
+        private const string AddHeader = "handyipc/cb/add";
+        private const string RemoveHeader = "handyipc/cb/remove";
+
+        public string Name { get; set; }
+
+        public string CallbackName { get; set; }
+
+        public string CallbackId { get; set; }
+
+        internal static bool TryParse(byte[] input, ISerializer serializer, out Subscription subscription)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}