feat(bindings): mqtt bindings

src/LEGO.AsyncAPI.Bindings/BindingsCollection.cs

@@ -6,6 +6,7 @@ namespace LEGO.AsyncAPI.Bindings
     using LEGO.AsyncAPI.Bindings.AMQP;
     using LEGO.AsyncAPI.Bindings.Http;
     using LEGO.AsyncAPI.Bindings.Kafka;
+    using LEGO.AsyncAPI.Bindings.MQTT;
     using LEGO.AsyncAPI.Bindings.Pulsar;
     using LEGO.AsyncAPI.Bindings.Sns;
     using LEGO.AsyncAPI.Bindings.Sqs;
@@ -53,6 +54,7 @@ public static TCollection Add<TCollection, TItem>(
             Sqs,
             Sns,
             AMQP,
+            MQTT,
         };
 
         public static IEnumerable<IBindingParser<IBinding>> Http => new List<IBindingParser<IBinding>>
@@ -98,5 +100,12 @@ public static TCollection Add<TCollection, TItem>(
             new AMQPOperationBinding(),
             new AMQPMessageBinding(),
         };
+
+        public static IEnumerable<IBindingParser<IBinding>> MQTT => new List<IBindingParser<IBinding>>
+        {
+            new MQTTServerBinding(),
+            new MQTTOperationBinding(),
+            new MQTTMessageBinding(),
+        };
     }
 }

src/LEGO.AsyncAPI.Bindings/MQTT/LastWill.cs

@@ -0,0 +1,48 @@
+// Copyright (c) The LEGO Group. All rights reserved.
+
+namespace LEGO.AsyncAPI.Bindings.MQTT
+{
+    using LEGO.AsyncAPI.Models.Interfaces;
+    using LEGO.AsyncAPI.Writers;
+    using System;
+
+    public class LastWill : IAsyncApiElement
+    {
+        /// <summary>
+        /// The topic where the Last Will and Testament message will be sent.
+        /// </summary>
+        public string Topic { get; set; }
+
+        /// <summary>
+        /// Defines how hard the broker/client will try to ensure that
+        /// the Last Will and Testament message is received.
+        /// Its value MUST be either 0, 1 or 2.
+        /// </summary>
+        public uint? QoS { get; set; }
+
+        /// <summary>
+        /// Last Will message.
+        /// </summary>
+        public string Message { get; set; }
+
+        /// <summary>
+        /// Whether the broker should retain the Last Will and Testament message or not.
+        /// </summary>
+        public bool Retain { get; set; }
+
+        public void Serialize(IAsyncApiWriter writer)
+        {
+            if (writer is null)
+            {
+                throw new ArgumentNullException(nameof(writer));
+            }
+
+            writer.WriteStartObject();
+            writer.WriteRequiredProperty("topic", this.Topic);
+            writer.WriteOptionalProperty("qos", (int?)this.QoS);
+            writer.WriteOptionalProperty("message", this.Message);
+            writer.WriteRequiredProperty("retain", this.Retain);
+            writer.WriteEndObject();
+        }
+    }
+}

src/LEGO.AsyncAPI.Bindings/MQTT/MQTTMessageBinding.cs

@@ -0,0 +1,65 @@
+// Copyright (c) The LEGO Group. All rights reserved.
+
+namespace LEGO.AsyncAPI.Bindings.MQTT
+{
+    using System;
+    using LEGO.AsyncAPI.Models;
+    using LEGO.AsyncAPI.Readers;
+    using LEGO.AsyncAPI.Readers.ParseNodes;
+    using LEGO.AsyncAPI.Writers;
+
+    /// <summary>
+    /// Binding class for MQTT messages.
+    /// </summary>
+    public class MQTTMessageBinding : MessageBinding<MQTTMessageBinding>
+    {
+        /// <summary>
+        /// Indicates the format of the payload.
+        /// Either: 0 (zero) for unspecified bytes, or 1 for UTF-8 encoded character data.
+        /// </summary>
+        public int? PayloadFormatIndicator { get; set; }
+
+        /// <summary>
+        /// Correlation Data is used to identify the request the response message is for.
+        /// </summary>
+        public AsyncApiSchema CorrelationData { get; set; }
+
+        /// <summary>
+        /// String describing the content type of the message payload.
+        /// This should not conflict with the contentType field of the associated AsyncAPI Message object.
+        /// </summary>
+        public string ContentType { get; set; }
+
+        /// <summary>
+        /// The topic (channel URI) for a response message.
+        /// </summary>
+        public string ResponseTopic { get; set; }
+
+        public override void SerializeProperties(IAsyncApiWriter writer)
+        {
+            if (writer is null)
+            {
+                throw new ArgumentNullException(nameof(writer));
+            }
+
+            writer.WriteStartObject();
+            writer.WriteOptionalProperty("payloadFormatIndicator", this.PayloadFormatIndicator);
+            writer.WriteOptionalObject("correlationData", this.CorrelationData, (w, h) => h.SerializeV2(w));
+            writer.WriteOptionalProperty("contentType", this.ContentType);
+            writer.WriteOptionalProperty("responseTopic", this.ResponseTopic);
+            writer.WriteOptionalProperty("bindingVersion", this.BindingVersion);
+            writer.WriteExtensions(this.Extensions);
+            writer.WriteEndObject();
+        }
+
+        public override string BindingKey => "mqtt";
+
+        protected override FixedFieldMap<MQTTMessageBinding> FixedFieldMap => new ()
+        {
+            { "payloadFormatIndicator", (a, n) => { a.PayloadFormatIndicator = n.GetIntegerValueOrDefault(); } },
+            { "correlationData", (a, n) => { a.CorrelationData = JsonSchemaDeserializer.LoadSchema(n); } },
+            { "contentType", (a, n) => { a.ContentType = n.GetScalarValue(); } },
+            { "responseTopic", (a, n) => { a.ResponseTopic = n.GetScalarValue(); } },
+        };
+    }
+}

src/LEGO.AsyncAPI.Bindings/MQTT/MQTTOperationBinding.cs

@@ -0,0 +1,61 @@
+// Copyright (c) The LEGO Group. All rights reserved.
+
+namespace LEGO.AsyncAPI.Bindings.MQTT
+{
+    using System;
+    using System.Collections.Generic;
+    using LEGO.AsyncAPI.Models;
+    using LEGO.AsyncAPI.Readers;
+    using LEGO.AsyncAPI.Readers.ParseNodes;
+    using LEGO.AsyncAPI.Writers;
+
+    /// <summary>
+    /// Binding class for MQTT operations.
+    /// </summary>
+    public class MQTTOperationBinding : OperationBinding<MQTTOperationBinding>
+    {
+        /// <summary>
+        /// Defines the Quality of Service (QoS) levels for the message flow between client and server.
+        /// Its value MUST be either 0 (At most once delivery), 1 (At least once delivery), or 2 (Exactly once delivery).
+        /// </summary>
+        public int QoS { get; set; }
+
+        /// <summary>
+        /// Whether the broker should retain the message or not.
+        /// </summary>
+        public bool Retain { get; set; }
+
+        /// <summary>
+        /// Interval in seconds or a Schema Object containing the definition of the lifetime of the message.
+        /// </summary>
+        public int? MessageExpiryInterval { get; set; }
+
+        public override string BindingKey => "mqtt";
+
+        protected override FixedFieldMap<MQTTOperationBinding> FixedFieldMap => new()
+        {
+            { "qos", (a, n) => { a.QoS = n.GetIntegerValue(); } },
+            { "retain", (a, n) => { a.Retain = n.GetBooleanValue(); } },
+            { "messageExpiryInterval", (a, n) => { a.MessageExpiryInterval = n.GetIntegerValueOrDefault(); } },
+        };
+
+        /// <summary>
+        /// Serialize to AsyncAPI V2 document without using reference.
+        /// </summary>
+        public override void SerializeProperties(IAsyncApiWriter writer)
+        {
+            if (writer is null)
+            {
+                throw new ArgumentNullException(nameof(writer));
+            }
+
+            writer.WriteStartObject();
+            writer.WriteRequiredProperty("qos", this.QoS);
+            writer.WriteRequiredProperty("retain", this.Retain);
+            writer.WriteOptionalProperty("messageExpiryInterval", this.MessageExpiryInterval);
+            writer.WriteOptionalProperty("bindingVersion", this.BindingVersion);
+            writer.WriteExtensions(this.Extensions);
+            writer.WriteEndObject();
+        }
+    }
+}

src/LEGO.AsyncAPI.Bindings/MQTT/MQTTServerBinding.cs

@@ -0,0 +1,93 @@
+// Copyright (c) The LEGO Group. All rights reserved.
+
+namespace LEGO.AsyncAPI.Bindings.MQTT
+{
+    using System;
+    using LEGO.AsyncAPI.Models;
+    using LEGO.AsyncAPI.Readers.ParseNodes;
+    using LEGO.AsyncAPI.Writers;
+
+    /// <summary>
+    /// Binding class for MQTT channel settings.
+    /// </summary>
+    public class MQTTServerBinding : ServerBinding<MQTTServerBinding>
+    {
+        /// <summary>
+        /// The client identifier.
+        /// </summary>
+        public string ClientId { get; set; }
+
+        /// <summary>
+        /// Whether to create a persistent connection or not.
+        /// When false, the connection will be persistent.
+        /// This is called clean start in MQTTv5.
+        /// </summary>
+        public bool? CleanSession { get; set; }
+
+        /// <summary>
+        /// Last Will and Testament configuration.
+        /// </summary>
+        public LastWill LastWill { get; set; }
+
+        /// <summary>
+        /// Interval in seconds of the longest period of time
+        /// the broker and the client can endure without sending a message.
+        /// </summary>
+        public int? KeepAlive { get; set; }
+
+        /// <summary>
+        /// Interval in seconds the broker maintains a session
+        /// for a disconnected client until this interval expires.
+        /// </summary>
+        public int? SessionExpiryInterval { get; set; }
+
+        /// <summary>
+        /// Number of bytes representing the maximum packet size
+        /// the client is willing to accept.
+        /// </summary>
+        public int? MaximumPacketSize { get; set; }
+
+        public override string BindingKey => "mqtt";
+
+        protected override FixedFieldMap<MQTTServerBinding> FixedFieldMap => new ()
+        {
+            { "bindingVersion", (a, n) => { a.BindingVersion = n.GetScalarValue(); } },
+            { "clientId", (a, n) => { a.ClientId = n.GetScalarValue(); } },
+            { "cleanSession", (a, n) => { a.CleanSession = n.GetBooleanValueOrDefault(); } },
+            { "lastWill", (a, n) => { a.LastWill = n.ParseMap(LastWillFixedFields); } },
+            { "keepAlive", (a, n) => { a.KeepAlive = n.GetIntegerValueOrDefault(); } },
+            { "sessionExpiryInterval", (a, n) => { a.SessionExpiryInterval = n.GetIntegerValueOrDefault(); } },
+            { "maximumPacketSize", (a, n) => { a.MaximumPacketSize = n.GetIntegerValueOrDefault(); } },
+        };
+
+        private static FixedFieldMap<LastWill> LastWillFixedFields = new ()
+        {
+            { "topic", (a, n) => { a.Topic = n.GetScalarValue(); } },
+            { "qos", (a, n) => { a.QoS = (uint?)n.GetIntegerValueOrDefault(); } },
+            { "message", (a, n) => { a.Message = n.GetScalarValue(); } },
+            { "retain", (a, n) => { a.Retain = n.GetBooleanValue(); } },
+        };
+
+        /// <summary>
+        /// Serialize to AsyncAPI V2 document without using reference.
+        /// </summary>
+        public override void SerializeProperties(IAsyncApiWriter writer)
+        {
+            if (writer is null)
+            {
+                throw new ArgumentNullException(nameof(writer));
+            }
+
+            writer.WriteStartObject();
+            writer.WriteRequiredProperty("clientId", this.ClientId);
+            writer.WriteOptionalProperty("cleanSession", this.CleanSession);
+            writer.WriteOptionalObject("lastWill", this.LastWill, (w, l) => l.Serialize(w));
+            writer.WriteOptionalProperty("keepAlive", this.KeepAlive);
+            writer.WriteOptionalProperty("sessionExpiryInterval", this.SessionExpiryInterval);
+            writer.WriteOptionalProperty("maximumPacketSize", this.MaximumPacketSize);
+            writer.WriteOptionalProperty(AsyncApiConstants.BindingVersion, this.BindingVersion);
+            writer.WriteExtensions(this.Extensions);
+            writer.WriteEndObject();
+        }
+    }
+}