14 files changed, 98 insertions, 12 deletions
diff --git a/MediaBrowser.Model/Session/BrowseRequest.cs b/MediaBrowser.Model/Session/BrowseRequest.cs
index f485d680e..1c997d584 100644
--- a/MediaBrowser.Model/Session/BrowseRequest.cs
+++ b/MediaBrowser.Model/Session/BrowseRequest.cs
@@ -1,3 +1,4 @@
+#nullable disable
 namespace MediaBrowser.Model.Session
 {
     /// <summary>
diff --git a/MediaBrowser.Model/Session/ClientCapabilities.cs b/MediaBrowser.Model/Session/ClientCapabilities.cs
index 5da4998e8..a85e6ff2a 100644
--- a/MediaBrowser.Model/Session/ClientCapabilities.cs
+++ b/MediaBrowser.Model/Session/ClientCapabilities.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 using System;
@@ -9,24 +10,28 @@ namespace MediaBrowser.Model.Session
     {
         public string[] PlayableMediaTypes { get; set; }
 
-        public string[] SupportedCommands { get; set; }
+        public GeneralCommandType[] SupportedCommands { get; set; }
 
         public bool SupportsMediaControl { get; set; }
+
         public bool SupportsContentUploading { get; set; }
+
         public string MessageCallbackUrl { get; set; }
 
         public bool SupportsPersistentIdentifier { get; set; }
+
         public bool SupportsSync { get; set; }
 
         public DeviceProfile DeviceProfile { get; set; }
 
         public string AppStoreUrl { get; set; }
+
         public string IconUrl { get; set; }
 
         public ClientCapabilities()
         {
             PlayableMediaTypes = Array.Empty<string>();
-            SupportedCommands = Array.Empty<string>();
+            SupportedCommands = Array.Empty<GeneralCommandType>();
             SupportsPersistentIdentifier = true;
         }
     }
diff --git a/MediaBrowser.Model/Session/GeneralCommand.cs b/MediaBrowser.Model/Session/GeneralCommand.cs
index 980e1f88b..77bb6bcf7 100644
--- a/MediaBrowser.Model/Session/GeneralCommand.cs
+++ b/MediaBrowser.Model/Session/GeneralCommand.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 using System;
@@ -7,7 +8,7 @@ namespace MediaBrowser.Model.Session
 {
     public class GeneralCommand
     {
-        public string Name { get; set; }
+        public GeneralCommandType Name { get; set; }
 
         public Guid ControllingUserId { get; set; }
 
diff --git a/MediaBrowser.Model/Session/GeneralCommandType.cs b/MediaBrowser.Model/Session/GeneralCommandType.cs
index 5a9042d5f..c58fa9a6b 100644
--- a/MediaBrowser.Model/Session/GeneralCommandType.cs
+++ b/MediaBrowser.Model/Session/GeneralCommandType.cs
@@ -43,6 +43,11 @@ namespace MediaBrowser.Model.Session
         Guide = 32,
         ToggleStats = 33,
         PlayMediaSource = 34,
-        PlayTrailers = 35
+        PlayTrailers = 35,
+        SetShuffleQueue = 36,
+        PlayState = 37,
+        PlayNext = 38,
+        ToggleOsdMenu = 39,
+        Play = 40
     }
 }
diff --git a/MediaBrowser.Model/Session/MessageCommand.cs b/MediaBrowser.Model/Session/MessageCommand.cs
index 473a7bccc..09abfbb3f 100644
--- a/MediaBrowser.Model/Session/MessageCommand.cs
+++ b/MediaBrowser.Model/Session/MessageCommand.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Model.Session
diff --git a/MediaBrowser.Model/Session/PlayRequest.cs b/MediaBrowser.Model/Session/PlayRequest.cs
index bdb2b2439..6a66465a2 100644
--- a/MediaBrowser.Model/Session/PlayRequest.cs
+++ b/MediaBrowser.Model/Session/PlayRequest.cs
@@ -1,12 +1,12 @@
+#nullable disable
 #pragma warning disable CS1591
 
 using System;
-using MediaBrowser.Model.Services;
 
 namespace MediaBrowser.Model.Session
 {
     /// <summary>
-    /// Class PlayRequest
+    /// Class PlayRequest.
     /// </summary>
     public class PlayRequest
     {
@@ -14,21 +14,18 @@ namespace MediaBrowser.Model.Session
         /// Gets or sets the item ids.
         /// </summary>
         /// <value>The item ids.</value>
-        [ApiMember(Name = "ItemIds", Description = "The ids of the items to play, comma delimited", IsRequired = true, DataType = "string", ParameterType = "query", Verb = "POST", AllowMultiple = true)]
         public Guid[] ItemIds { get; set; }
 
         /// <summary>
-        /// Gets or sets the start position ticks that the first item should be played at
+        /// Gets or sets the start position ticks that the first item should be played at.
         /// </summary>
         /// <value>The start position ticks.</value>
-        [ApiMember(Name = "StartPositionTicks", Description = "The starting position of the first item.", IsRequired = false, DataType = "string", ParameterType = "query", Verb = "POST")]
         public long? StartPositionTicks { get; set; }
 
         /// <summary>
         /// Gets or sets the play command.
         /// </summary>
         /// <value>The play command.</value>
-        [ApiMember(Name = "PlayCommand", Description = "The type of play command to issue (PlayNow, PlayNext, PlayLast). Clients who have not yet implemented play next and play last may play now.", IsRequired = true, DataType = "string", ParameterType = "query", Verb = "POST")]
         public PlayCommand PlayCommand { get; set; }
 
         /// <summary>
@@ -38,8 +35,11 @@ namespace MediaBrowser.Model.Session
         public Guid ControllingUserId { get; set; }
 
         public int? SubtitleStreamIndex { get; set; }
+
         public int? AudioStreamIndex { get; set; }
+
         public string MediaSourceId { get; set; }
+
         public int? StartIndex { get; set; }
     }
 }
diff --git a/MediaBrowser.Model/Session/PlaybackProgressInfo.cs b/MediaBrowser.Model/Session/PlaybackProgressInfo.cs
index 5687ba84b..73dbe6a2d 100644
--- a/MediaBrowser.Model/Session/PlaybackProgressInfo.cs
+++ b/MediaBrowser.Model/Session/PlaybackProgressInfo.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 using System;
@@ -87,16 +88,19 @@ namespace MediaBrowser.Model.Session
         /// </summary>
         /// <value>The play method.</value>
         public PlayMethod PlayMethod { get; set; }
+
         /// <summary>
         /// Gets or sets the live stream identifier.
         /// </summary>
         /// <value>The live stream identifier.</value>
         public string LiveStreamId { get; set; }
+
         /// <summary>
         /// Gets or sets the play session identifier.
         /// </summary>
         /// <value>The play session identifier.</value>
         public string PlaySessionId { get; set; }
+
         /// <summary>
         /// Gets or sets the repeat mode.
         /// </summary>
@@ -104,6 +108,7 @@ namespace MediaBrowser.Model.Session
         public RepeatMode RepeatMode { get; set; }
 
         public QueueItem[] NowPlayingQueue { get; set; }
+
         public string PlaylistItemId { get; set; }
     }
 
@@ -117,6 +122,7 @@ namespace MediaBrowser.Model.Session
     public class QueueItem
     {
         public Guid Id { get; set; }
+
         public string PlaylistItemId { get; set; }
     }
 }
diff --git a/MediaBrowser.Model/Session/PlaybackStopInfo.cs b/MediaBrowser.Model/Session/PlaybackStopInfo.cs
index f8cfacc20..aa29bb249 100644
--- a/MediaBrowser.Model/Session/PlaybackStopInfo.cs
+++ b/MediaBrowser.Model/Session/PlaybackStopInfo.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 using System;
@@ -61,6 +62,7 @@ namespace MediaBrowser.Model.Session
         public string NextMediaType { get; set; }
 
         public string PlaylistItemId { get; set; }
+
         public QueueItem[] NowPlayingQueue { get; set; }
     }
 }
diff --git a/MediaBrowser.Model/Session/PlayerStateInfo.cs b/MediaBrowser.Model/Session/PlayerStateInfo.cs
index 0f9956873..0f10605ea 100644
--- a/MediaBrowser.Model/Session/PlayerStateInfo.cs
+++ b/MediaBrowser.Model/Session/PlayerStateInfo.cs
@@ -1,3 +1,4 @@
+#nullable disable
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Model.Session
diff --git a/MediaBrowser.Model/Session/PlaystateRequest.cs b/MediaBrowser.Model/Session/PlaystateRequest.cs
index 493a8063a..ba2c024b7 100644
--- a/MediaBrowser.Model/Session/PlaystateRequest.cs
+++ b/MediaBrowser.Model/Session/PlaystateRequest.cs
@@ -12,6 +12,6 @@ namespace MediaBrowser.Model.Session
         /// Gets or sets the controlling user identifier.
         /// </summary>
         /// <value>The controlling user identifier.</value>
-        public string ControllingUserId { get; set; }
+        public string? ControllingUserId { get; set; }
     }
 }
diff --git a/MediaBrowser.Model/Session/SessionMessageType.cs b/MediaBrowser.Model/Session/SessionMessageType.cs
new file mode 100644
index 000000000..23c41026d
--- /dev/null
+++ b/MediaBrowser.Model/Session/SessionMessageType.cs
@@ -0,0 +1,50 @@
+#pragma warning disable CS1591
+
+namespace MediaBrowser.Model.Session
+{
+    /// <summary>
+    /// The different kinds of messages that are used in the WebSocket api.
+    /// </summary>
+    public enum SessionMessageType
+    {
+        // Server -> Client
+        ForceKeepAlive,
+        GeneralCommand,
+        UserDataChanged,
+        Sessions,
+        Play,
+        SyncPlayCommand,
+        SyncPlayGroupUpdate,
+        PlayState,
+        RestartRequired,
+        ServerShuttingDown,
+        ServerRestarting,
+        LibraryChanged,
+        UserDeleted,
+        UserUpdated,
+        SeriesTimerCreated,
+        TimerCreated,
+        SeriesTimerCancelled,
+        TimerCancelled,
+        RefreshProgress,
+        ScheduledTaskEnded,
+        PackageInstallationCancelled,
+        PackageInstallationFailed,
+        PackageInstallationCompleted,
+        PackageInstalling,
+        PackageUninstalled,
+        ActivityLogEntry,
+        ScheduledTasksInfo,
+
+        // Client -> Server
+        ActivityLogEntryStart,
+        ActivityLogEntryStop,
+        SessionsStart,
+        SessionsStop,
+        ScheduledTasksInfoStart,
+        ScheduledTasksInfoStop,
+
+        // Shared
+        KeepAlive,
+    }
+}
diff --git a/MediaBrowser.Model/Session/SessionUserInfo.cs b/MediaBrowser.Model/Session/SessionUserInfo.cs
index 42a56b92b..4d6f35efc 100644
--- a/MediaBrowser.Model/Session/SessionUserInfo.cs
+++ b/MediaBrowser.Model/Session/SessionUserInfo.cs
@@ -1,3 +1,4 @@
+#nullable disable
 using System;
 
 namespace MediaBrowser.Model.Session
@@ -12,6 +13,7 @@ namespace MediaBrowser.Model.Session
         /// </summary>
         /// <value>The user identifier.</value>
         public Guid UserId { get; set; }
+
         /// <summary>
         /// Gets or sets the name of the user.
         /// </summary>
diff --git a/MediaBrowser.Model/Session/TranscodingInfo.cs b/MediaBrowser.Model/Session/TranscodingInfo.cs
index 8f4e688f0..e832c2f6f 100644
--- a/MediaBrowser.Model/Session/TranscodingInfo.cs
+++ b/MediaBrowser.Model/Session/TranscodingInfo.cs
@@ -1,28 +1,39 @@
+#nullable disable
 #pragma warning disable CS1591
 
+using System;
+
 namespace MediaBrowser.Model.Session
 {
     public class TranscodingInfo
     {
         public string AudioCodec { get; set; }
+
         public string VideoCodec { get; set; }
+
         public string Container { get; set; }
+
         public bool IsVideoDirect { get; set; }
+
         public bool IsAudioDirect { get; set; }
+
         public int? Bitrate { get; set; }
 
         public float? Framerate { get; set; }
+
         public double? CompletionPercentage { get; set; }
 
         public int? Width { get; set; }
+
         public int? Height { get; set; }
+
         public int? AudioChannels { get; set; }
 
         public TranscodeReason[] TranscodeReasons { get; set; }
 
         public TranscodingInfo()
         {
-            TranscodeReasons = new TranscodeReason[] { };
+            TranscodeReasons = Array.Empty<TranscodeReason>();
         }
     }
 
diff --git a/MediaBrowser.Model/Session/UserDataChangeInfo.cs b/MediaBrowser.Model/Session/UserDataChangeInfo.cs
index 0872eb4b1..0fd24edcc 100644
--- a/MediaBrowser.Model/Session/UserDataChangeInfo.cs
+++ b/MediaBrowser.Model/Session/UserDataChangeInfo.cs
@@ -1,3 +1,4 @@
+#nullable disable
 using MediaBrowser.Model.Dto;
 
 namespace MediaBrowser.Model.Session