Connect to MQTT server in backend and publish dispense message

backend/.gitignore

@@ -1,3 +1,4 @@
 obj/
 bin/
+appsettings.json
 

backend/ApplicationState.cs

@@ -0,0 +1,9 @@
+using MQTTnet.Client;
+
+namespace backend.Application
+{
+	public static class ApplicationState
+	{
+		public static IMqttClient? MqttClient { get; set; }
+	}
+}

backend/Controllers/DispenserController.cs

@@ -1,4 +1,6 @@
 using Microsoft.AspNetCore.Mvc;
+using MQTTnet;
+using backend.Application;
 
 namespace backend.Controllers;
 
@@ -8,8 +10,14 @@ public class DispenserController : ControllerBase
     [HttpPost("Dispense")]
     public void Dispense()
     {
-		// TODO send MQTT to arduino
 		Console.WriteLine("Dispensing..");
+
+		var message = new MqttApplicationMessageBuilder()
+			.WithTopic("dispense")
+			.WithPayload("dispense")
+			.Build();
+
+		ApplicationState.MqttClient!.PublishAsync(message, CancellationToken.None);
     }
 }
 

backend/Program.cs

@@ -1,3 +1,7 @@
+using MQTTnet;
+using MQTTnet.Client;
+using backend.Application;
+
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
@@ -24,4 +28,25 @@ app.UseAuthorization();
 
 app.MapControllers();
 
+var configuration = app.Services.GetRequiredService<IConfiguration>();
+
+// Connect via MQTT
+
+Console.WriteLine($"Connecting to MQTT server: {configuration["Mqtt:Host"]}:{configuration["Mqtt:Port"]}...");
+
+var mqttClient = new MqttFactory().CreateMqttClient();
+
+var options = new MqttClientOptionsBuilder()
+	.WithTcpServer(configuration["Mqtt:Host"], int.Parse(configuration["Mqtt:Port"]!))
+	.WithCredentials(configuration["Mqtt:Username"], configuration["Mqtt:Password"])
+	.WithTlsOptions(new MqttClientTlsOptionsBuilder().Build())
+	.Build();
+
+await mqttClient.ConnectAsync(options, CancellationToken.None);
+
+ApplicationState.MqttClient = mqttClient;
+
+Console.WriteLine("Connected");
+
 app.Run();
+

backend/appsettings.Development.json

@@ -1,8 +0,0 @@
-{
-  "Logging": {
-    "LogLevel": {
-      "Default": "Information",
-      "Microsoft.AspNetCore": "Warning"
-    }
-  }
-}

backend/appsettings.json

@@ -1,9 +0,0 @@
-{
-  "Logging": {
-    "LogLevel": {
-      "Default": "Information",
-      "Microsoft.AspNetCore": "Warning"
-    }
-  },
-  "AllowedHosts": "*"
-}

backend/appsettings.template.json

@@ -0,0 +1,15 @@
+{
+	"Logging": {
+		"LogLevel": {
+			"Default": "Information",
+			"Microsoft.AspNetCore": "Warning"
+		}
+	},
+	"AllowedHosts": "*",
+	"Mqtt": {
+		"Host": "example.hivemq.cloud",
+		"Port": 8883,
+		"Username": "user",
+		"Password": "password"
+	}
+}

backend/backend.csproj

@@ -7,8 +7,8 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.App" Version="2.2.8" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="7.0.13" />
+    <PackageReference Include="MQTTnet" Version="4.3.1.873" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
   </ItemGroup>