Make protocol project nullable

src/Microsoft.Azure.SignalR.Protocols/CheckWithAckMessage.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {

src/Microsoft.Azure.SignalR.Protocols/CloseWithAckMessage.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 using System;
 using System.Collections.Generic;
@@ -22,7 +23,7 @@ public abstract class CloseWithAckMessage : ExtensibleServiceMessage, IAckableMe
         /// <summary>
         /// Gets or sets the reason for the close.
         /// </summary>
-        public string Reason { get; set; }
+        public string? Reason { get; set; }
 
         public CloseWithAckMessage(int ackId)
         {
@@ -35,7 +36,7 @@ public abstract class CloseMultiConnectionsWithAckMessage : CloseWithAckMessage
         /// <summary>
         /// Gets or sets the list of excluded connection Ids.
         /// </summary>
-        public IReadOnlyList<string> ExcludedList { get; set; }
+        public IReadOnlyList<string>? ExcludedList { get; set; }
 
         public CloseMultiConnectionsWithAckMessage(int ackId) : base(ackId) { }
     }

src/Microsoft.Azure.SignalR.Protocols/ConnectionMessage.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 using System;
 using System.Buffers;
@@ -79,7 +80,7 @@ public OpenConnectionMessage(string connectionId, Claim[] claims, IDictionary<st
         /// <summary>
         /// Gets or sets the protocol for new connection.
         /// </summary>
-        public string Protocol { get; set; }
+        public string? Protocol { get; set; }
     }
 
     /// <summary>
@@ -98,7 +99,7 @@ public class CloseConnectionMessage : ConnectionMessage, IMessageWithTracingId
         /// <param name="connectionId">The connection Id.</param>
         /// <param name="errorMessage">Optional error message.</param>
         /// <param name="headers">A <see cref="IDictionary{TKey,TValue}"/> associated with the connection.</param>
-        public CloseConnectionMessage(string connectionId, string errorMessage, IDictionary<string, StringValues> headers = null) : base(connectionId)
+        public CloseConnectionMessage(string connectionId, string errorMessage, IDictionary<string, StringValues>? headers = null) : base(connectionId)
         {
             ErrorMessage = errorMessage ?? "";
             Headers = headers ?? new Dictionary<string, StringValues>();
@@ -239,7 +240,7 @@ public ClientCompletionMessage(string invocationId, string connectionId, string
         /// <summary>
         /// Gets or sets the connection protocol.
         /// </summary>
-        public string Protocol { get; set; }
+        public string? Protocol { get; set; }
 
         /// <summary>
         /// Gets or sets the binary payload.

src/Microsoft.Azure.SignalR.Protocols/GroupMessage.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {

src/Microsoft.Azure.SignalR.Protocols/IHasDataMessageType.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {

src/Microsoft.Azure.SignalR.Protocols/IHasProtocol.cs

@@ -1,10 +1,11 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {
     public interface IHasProtocol
     {
-        string Protocol { get; set; }
+        string? Protocol { get; set; }
     }
 }

src/Microsoft.Azure.SignalR.Protocols/IHasSubscriberFilter.cs

@@ -1,10 +1,11 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {
     public interface IHasSubscriberFilter
     {
-        string Filter { get; set; }
+        string? Filter { get; set; }
     }
 }

src/Microsoft.Azure.SignalR.Protocols/IHasTtl.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {

src/Microsoft.Azure.SignalR.Protocols/IMessageWithTracingId.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {

src/Microsoft.Azure.SignalR.Protocols/IPartializable.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol
 {

src/Microsoft.Azure.SignalR.Protocols/IServiceProtocol.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 using System;
 using System.Buffers;
@@ -22,7 +23,7 @@ public interface IServiceProtocol
         /// <param name="input">The serialized representation of the message.</param>
         /// <param name="message">When this method returns <c>true</c>, contains the parsed message.</param>
         /// <returns>A value that is <c>true</c> if the <see cref="ServiceMessage"/> was successfully parsed; otherwise, <c>false</c>.</returns>
-        bool TryParseMessage(ref ReadOnlySequence<byte> input, out ServiceMessage message);
+        bool TryParseMessage(ref ReadOnlySequence<byte> input, out ServiceMessage? message);
 
         /// <summary>
         /// Writes the specified <see cref="ServiceMessage"/> to a writer.

src/Microsoft.Azure.SignalR.Protocols/MulticastDataMessage.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 using System;
 using System.Collections.Generic;
@@ -41,7 +42,7 @@ protected MulticastDataMessage(IDictionary<string, ReadOnlyMemory<byte>> payload
         /// <summary>
         /// Filter out the subscribers to send messages to
         /// </summary>
-        public string Filter { get; set; }
+        public string? Filter { get; set; }
     }
 
     /// <summary>
@@ -128,7 +129,7 @@ public class BroadcastDataMessage : MulticastDataMessage, IPartitionableMessage
         /// <summary>
         /// Gets or sets the list of excluded connection Ids.
         /// </summary>
-        public IReadOnlyList<string> ExcludedList { get; set; }
+        public IReadOnlyList<string>? ExcludedList { get; set; }
 
         public byte PartitionKey => Key;
 
@@ -147,7 +148,7 @@ public BroadcastDataMessage(IDictionary<string, ReadOnlyMemory<byte>> payloads,
         /// <param name="excludedList">The list of excluded connection Ids.</param>
         /// <param name="payloads">The payload dictionary which contains binary payload of multiple protocols.</param>
         /// <param name="tracingId">The tracing Id of the message.</param>
-        public BroadcastDataMessage(IReadOnlyList<string> excludedList, IDictionary<string, ReadOnlyMemory<byte>> payloads, ulong? tracingId = null) : base(payloads, tracingId)
+        public BroadcastDataMessage(IReadOnlyList<string>? excludedList, IDictionary<string, ReadOnlyMemory<byte>> payloads, ulong? tracingId = null) : base(payloads, tracingId)
         {
             ExcludedList = excludedList;
         }
@@ -168,17 +169,17 @@ public class GroupBroadcastDataMessage : MulticastDataMessage, IPartitionableMes
         /// <summary>
         /// Gets or sets the list of excluded connection Ids.
         /// </summary>
-        public IReadOnlyList<string> ExcludedList { get; set; }
+        public IReadOnlyList<string>? ExcludedList { get; set; }
 
         /// <summary>
         /// Gets or sets the list of excluded user Ids.
         /// </summary>
-        public IReadOnlyList<string> ExcludedUserList { get; set; }
+        public IReadOnlyList<string>? ExcludedUserList { get; set; }
 
         /// <summary>
         /// Gets or sets the user ID of the message caller
         /// </summary>
-        public string CallerUserId { get; set; }
+        public string? CallerUserId { get; set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="GroupBroadcastDataMessage"/> class.
@@ -198,7 +199,7 @@ public GroupBroadcastDataMessage(string groupName, IDictionary<string, ReadOnlyM
         /// <param name="excludedList">The list of excluded connection Ids.</param>
         /// <param name="payloads">The payload dictionary which contains binary payload of multiple protocols.</param>
         /// <param name="tracingId">The tracing Id of the message.</param>
-        public GroupBroadcastDataMessage(string groupName, IReadOnlyList<string> excludedList, IDictionary<string, ReadOnlyMemory<byte>> payloads, ulong? tracingId = null)
+        public GroupBroadcastDataMessage(string groupName, IReadOnlyList<string>? excludedList, IDictionary<string, ReadOnlyMemory<byte>> payloads, ulong? tracingId = null)
             : base(payloads, tracingId)
         {
             GroupName = groupName;

src/Microsoft.Azure.SignalR.Protocols/ServiceMessage.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 using System;
 
@@ -68,7 +69,7 @@ public abstract class ServiceMessage
         /// Clone should make a copy of everything that may get modified throughout the lifetime of the message
         /// The default implementation is a shallow copy as it fits the current needs.
         /// </summary>
-        public virtual ServiceMessage Clone() => MemberwiseClone() as ServiceMessage;
+        public virtual ServiceMessage Clone() => (MemberwiseClone() as ServiceMessage)!;
 
         public static byte GeneratePartitionKey(string input)
         {
@@ -238,13 +239,13 @@ public class AccessKeyRequestMessage : ExtensibleServiceMessage
         /// <summary>
         /// Gets or sets the Azure Active Directory token.
         /// </summary>
-        public string Token { get; set; }
+        public string? Token { get; set; }
 
         /// <summary>
         /// Gets or sets the key Id.
         /// <c>null</c>
         /// </summary>
-        public string Kid { get; set; }
+        public string? Kid { get; set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AccessKeyRequestMessage"/> class.
@@ -271,22 +272,22 @@ public class AccessKeyResponseMessage : ExtensibleServiceMessage
         /// <summary>
         /// Gets or sets the key Id.
         /// </summary>
-        public string Kid { get; set; }
+        public string? Kid { get; set; }
 
         /// <summary>
         /// Gets or sets the access key.
         /// </summary>
-        public string AccessKey { get; set; }
+        public string? AccessKey { get; set; }
 
         /// <summary>
         /// Gets or sets error type.
         /// </summary>
-        public string ErrorType { get; set; }
+        public string? ErrorType { get; set; }
 
         /// <summary>
         /// Gets or sets error message.
         /// </summary>
-        public string ErrorMessage { get; set; }
+        public string? ErrorMessage { get; set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AccessKeyResponseMessage"/> class.
@@ -342,7 +343,7 @@ public class HandshakeRequestMessage : ExtensibleServiceMessage
         /// <summary>
         /// Gets or sets the target of service connection, only work for OnDemand connections.
         /// </summary>
-        public string Target { get; set; }
+        public string? Target { get; set; }
 
         /// <summary>
         /// Gets or sets the migratable flag.
@@ -397,7 +398,7 @@ public class HandshakeResponseMessage : ExtensibleServiceMessage
         /// <summary>
         /// Gets or sets the id of this connection.
         /// </summary>
-        public string ConnectionId { get; set; }
+        public string? ConnectionId { get; set; }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="HandshakeResponseMessage"/> class.

src/Microsoft.Azure.SignalR.Protocols/ServiceProtocol.cs

@@ -1,9 +1,11 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 using System;
 using System.Buffers;
 using System.Collections.Generic;
+using System.Collections.ObjectModel;
 using System.Diagnostics;
 using System.IO;
 using System.Security.Claims;
@@ -17,13 +19,17 @@ namespace Microsoft.Azure.SignalR.Protocol
     /// </summary>
     public class ServiceProtocol : IServiceProtocol
     {
+        private static readonly IDictionary<string, ReadOnlyMemory<byte>> EmptyReadOnlyMemoryDictionary = new ReadOnlyDictionary<string, ReadOnlyMemory<byte>>(new Dictionary<string, ReadOnlyMemory<byte>>());
+
+        private static readonly IDictionary<string, StringValues> EmptyStringValuesDictionary = new ReadOnlyDictionary<string, StringValues>(new Dictionary<string, StringValues>());
+
         private static readonly int ProtocolVersion = 1;
 
         /// <inheritdoc />
         public int Version => ProtocolVersion;
 
         /// <inheritdoc />
-        public bool TryParseMessage(ref ReadOnlySequence<byte> input, out ServiceMessage message)
+        public bool TryParseMessage(ref ReadOnlySequence<byte> input, out ServiceMessage? message)
         {
             if (!BinaryMessageParser.TryParseMessage(ref input, out var payload))
             {
@@ -37,7 +43,7 @@ public bool TryParseMessage(ref ReadOnlySequence<byte> input, out ServiceMessage
             return true;
         }
 
-        private static ServiceMessage ParseMessage(ref MessagePackReader reader)
+        private static ServiceMessage? ParseMessage(ref MessagePackReader reader)
         {
             var arrayLength = reader.ReadArrayHeader();
 
@@ -715,7 +721,7 @@ private static void WriteConnectionFlowControlMessage(ref MessagePackWriter writ
             message.WriteExtensionMembers(ref writer);
         }
 
-        private static void WriteStringArray(ref MessagePackWriter writer, IReadOnlyList<string> array)
+        private static void WriteStringArray(ref MessagePackWriter writer, IReadOnlyList<string>? array)
         {
             if (array?.Count > 0)
             {
@@ -1351,7 +1357,7 @@ private static Claim[] ReadClaims(ref MessagePackReader reader)
                 return claims;
             }
 
-            return null;
+            return [];
         }
 
         private static IDictionary<string, ReadOnlyMemory<byte>> ReadPayloads(ref MessagePackReader reader)
@@ -1370,10 +1376,10 @@ private static IDictionary<string, ReadOnlyMemory<byte>> ReadPayloads(ref Messag
                 return payloads;
             }
 
-            return null;
+            return EmptyReadOnlyMemoryDictionary;
         }
 
-        private static Dictionary<string, StringValues> ReadHeaders(ref MessagePackReader reader)
+        private static IDictionary<string, StringValues> ReadHeaders(ref MessagePackReader reader)
         {
             var headerCount = ReadMapLength(ref reader, "headers");
             if (headerCount > 0)
@@ -1394,7 +1400,7 @@ private static Dictionary<string, StringValues> ReadHeaders(ref MessagePackReade
                 return headers;
             }
 
-            return new Dictionary<string, StringValues>(StringComparer.OrdinalIgnoreCase);
+            return EmptyStringValuesDictionary;
         }
 
         private static bool ReadBoolean(ref MessagePackReader reader, string field)
@@ -1472,7 +1478,7 @@ private static string[] ReadStringArray(ref MessagePackReader reader, string fie
                 return array;
             }
 
-            return null;
+            return [];
         }
 
         private static byte[] ReadBytes(ref MessagePackReader reader, string field)

src/Microsoft.Azure.SignalR.Protocols/ServiceProtocolConstants.cs

@@ -1,5 +1,6 @@
 // Copyright (c) Microsoft. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
+#nullable enable
 
 namespace Microsoft.Azure.SignalR.Protocol;