Before changing Piece[,] to Dictionary<string,Piece>

Gameboard.ShogiUI.Sockets/Managers/ActiveSessionManager.cs

@@ -0,0 +1,33 @@
+using Gameboard.ShogiUI.Sockets.Models;
+using System.Collections.Concurrent;
+
+namespace Gameboard.ShogiUI.Sockets.Managers
+{
+  public interface IActiveSessionManager
+  {
+    void Add(Session session);
+    Session? Get(string sessionName);
+  }
+
+  // TODO: Consider moving this class' functionality into the ConnectionManager class.
+  public class ActiveSessionManager : IActiveSessionManager
+  {
+    private readonly ConcurrentDictionary<string, Session> Sessions;
+
+    public ActiveSessionManager()
+    {
+      Sessions = new ConcurrentDictionary<string, Session>();
+    }
+
+    public void Add(Session session) => Sessions.TryAdd(session.Name, session);
+
+    public Session? Get(string sessionName)
+    {
+      if (Sessions.TryGetValue(sessionName, out var session))
+      {
+        return session;
+      }
+      return null;
+    }
+  }
+}