Support disconnect message from object explorer

MarkMpn.Sql4Cds.LanguageServer/ObjectExplorer/Contracts/CloseSessionParams.cs

@@ -0,0 +1,14 @@
+namespace MarkMpn.Sql4Cds.LanguageServer.ObjectExplorer.Contracts
+{
+    /// <summary>
+    /// Parameters to the <see cref="CloseSessionRequest"/>.
+    /// </summary>
+    public class CloseSessionParams
+    {
+        /// <summary>
+        /// The Id returned from a <see cref="CreateSessionRequest"/>. This
+        /// is used to disambiguate between different trees. 
+        /// </summary>
+        public string SessionId { get; set; }
+    }
+}

MarkMpn.Sql4Cds.LanguageServer/ObjectExplorer/Contracts/CloseSessionRequest.cs

@@ -0,0 +1,15 @@
+using MarkMpn.Sql4Cds.LanguageServer.Connection.Contracts;
+using Microsoft.VisualStudio.LanguageServer.Protocol;
+
+namespace MarkMpn.Sql4Cds.LanguageServer.ObjectExplorer.Contracts
+{
+    /// <summary>
+    /// Closes an Object Explorer tree session for a specific connection.
+    /// </summary>
+    public class CloseSessionRequest
+    {
+        public const string MessageName = "objectexplorer/closesession";
+
+        public static readonly LspRequest<CloseSessionParams, CloseSessionResponse> Type = new LspRequest<CloseSessionParams, CloseSessionResponse>(MessageName);
+    }
+}

MarkMpn.Sql4Cds.LanguageServer/ObjectExplorer/Contracts/CloseSessionResponse.cs

@@ -0,0 +1,21 @@
+namespace MarkMpn.Sql4Cds.LanguageServer.ObjectExplorer.Contracts
+{
+    /// <summary>
+    /// Information returned from a <see cref="CloseSessionRequest"/>.
+    /// Contains success information, a <see cref="SessionId"/> to be used when
+    /// requesting closing an existing session.
+    /// </summary>
+    public class CloseSessionResponse
+    {
+        /// <summary>
+        /// Boolean indicating if the session was closed successfully 
+        /// </summary>
+        public bool Success { get; set; }
+
+        /// <summary>
+        /// Unique ID to use when sending any requests for objects in the
+        /// tree under the node
+        /// </summary>
+        public string SessionId { get; set; }
+    }
+}

MarkMpn.Sql4Cds.LanguageServer/ObjectExplorer/Contracts/SessionDisconnectedNotification.cs

@@ -0,0 +1,37 @@
+using Microsoft.VisualStudio.LanguageServer.Protocol;
+
+namespace MarkMpn.Sql4Cds.LanguageServer.ObjectExplorer.Contracts
+{
+    /// <summary>
+    /// Information returned when a session is disconnected.
+    /// Contains success information and a <see cref="SessionId"/>
+    /// </summary>
+    public class SessionDisconnectedParameters
+    {
+        /// <summary>
+        /// Boolean indicating if the connection was successful
+        /// </summary>
+        public bool Success { get; set; }
+
+        /// <summary>
+        /// Unique ID to use when sending any requests for objects in the
+        /// tree under the node
+        /// </summary>
+        public string SessionId { get; set; }
+
+        /// <summary>
+        /// Error message returned from the engine for a object explorer session failure reason, if any.
+        /// </summary>
+        public string ErrorMessage { get; set; }
+    }
+
+    /// <summary>
+    /// Session disconnected notification
+    /// </summary>
+    public class SessionDisconnectedNotification
+    {
+        public const string MessageName = "objectexplorer/sessiondisconnected";
+
+        public static readonly LspNotification<SessionDisconnectedParameters> Type = new LspNotification<SessionDisconnectedParameters>(MessageName);
+    }
+}

MarkMpn.Sql4Cds.LanguageServer/ObjectExplorer/ObjectExplorerHandler.cs

@@ -29,6 +29,7 @@ public void Initialize(JsonRpc lsp)
             lsp.AddHandler(CreateSessionRequest.Type, HandleCreateSession);
             lsp.AddHandler(ExpandRequest.Type, HandleExpand);
             lsp.AddHandler(RefreshRequest.Type, HandleRefresh);
+            lsp.AddHandler(CloseSessionRequest.Type, HandleCloseSession);
         }
 
         public CreateSessionResponse HandleCreateSession(ConnectionDetails request)
@@ -61,6 +62,24 @@ public CreateSessionResponse HandleCreateSession(ConnectionDetails request)
             return new CreateSessionResponse { SessionId = session.SessionId };
         }
 
+        public CloseSessionResponse HandleCloseSession(CloseSessionParams request)
+        {
+            _connectionManager.Disconnect(request.SessionId);
+
+            _ = _lsp.NotifyAsync(SessionDisconnectedNotification.Type, new SessionDisconnectedParameters
+            {
+                SessionId = request.SessionId,
+                Success = true,
+                ErrorMessage = null
+            });
+
+            return new CloseSessionResponse
+            {
+                SessionId = request.SessionId,
+                Success = true
+            };
+        }
+
         public bool HandleExpand(ExpandParams request)
         {
             var session = _connectionManager.GetConnection(request.SessionId);