MQTT

MQTT is a standard messaging protocol for the Internet of Things (IoT). It is designed as an extremely lightweight publish/subscribe messaging transport that is ideal for connecting remote devices with a small code footprint and minimal network bandwidth. MQTT today is used in a wide variety of industries, such as automotive, manufacturing, telecommunications, oil and gas, etc.

To work with MQTT protocol, NBomber provides NBomber.MQTT plugin that includes functionality for sending and receiving messages, including tracking of data transfer and status codes.

info

To install NBomber.MQTT package you should execute the following dotnet command:

dotnet add package NBomber.MQTT

MQTT API

MQTT plugin provides a wrapper over the popular library MQTTnet. The wrapper implements basic methods for publishing and receiving messages.

var payload = Data.GenerateRandomBytes(200);

var scenario = Scenario.Create("mqtt_scenario", async ctx =>
{
    using var client = new MqttClient(new MqttFactory().CreateMqttClient());    
    
    var topic = $"/clients/{ctx.ScenarioInfo.InstanceId}";

    var connect = await Step.Run("connect", ctx, async () =>
    {
        var clientOptions = new MqttClientOptionsBuilder()
            .WithTcpServer("localhost")
            // .WithWebSocketServer(options => options.WithUri("ws://localhost:8083/mqtt"))
            .WithCleanSession()
            .WithClientId($"client_{ctx.ScenarioInfo.InstanceId}")
            .Build();

        var response = await client.Connect(clientOptions);
        return response;
    });

    var subscribe = await Step.Run("subscribe", ctx, () => client.Subscribe(topic));

    var publish = await Step.Run("publish", ctx, async () =>
    {
        var msg = new MqttApplicationMessageBuilder()
            .WithTopic(topic)
            .WithPayload(payload)
            .Build();

        var response = await client.Publish(msg);
        return response;
    });

    var receive = await Step.Run("receive", ctx, async () =>
    {
        var response = await client.Receive();
        return response;
    });

    var disconnect = await Step.Run("disconnect", ctx, () => client.Disconnect());

    return Response.Ok();
});

You can find the complete example by this link.

Original IMqttClient

NBomber MQTT plugin is basically a wrapper over the popular library MQTTnet. If you need to work with the original IMqttClient from MQTTnet library, you can use public Client property. All native methods are available for usage.

using var mqtt = new MqttClient(new MqttFactory().CreateMqttClient());

var originalClient = mqtt.Client;