Setup standard src, test folder structure. Add unit test project.

src/ServiceHost/MessageProtocol/EventContext.cs

@@ -0,0 +1,33 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.Threading.Tasks;
+
+namespace Microsoft.SqlTools.EditorServices.Protocol.MessageProtocol
+{
+    /// <summary>
+    /// Provides context for a received event so that handlers
+    /// can write events back to the channel.
+    /// </summary>
+    public class EventContext
+    {
+        private MessageWriter messageWriter;
+
+        public EventContext(MessageWriter messageWriter)
+        {
+            this.messageWriter = messageWriter;
+        }
+
+        public async Task SendEvent<TParams>(
+            EventType<TParams> eventType, 
+            TParams eventParams)
+        {
+            await this.messageWriter.WriteEvent(
+                eventType,
+                eventParams);
+        }
+    }
+}
+