Mqtt client with web API

[mikolajwalus]

Describe your question

I have two questions regarding propper implementation of two simple (from description point of view) features.

1. Implement mechanism of publishing message on http request

As per documentation this ref repo is propper way of implementing client in .net core.

I will inject it via provider as in repo

    [Route("api/[controller]")]
    [ApiController]
    public class SampleController : ControllerBase
    {
        private readonly IMqttClientService mqttClientService;

        public SampleController(MqttClientServiceProvider provider)
        {
            mqttClientService = provider.MqttClientService;
        }

        [HttpPost]
        async Task<IActionResult> SendMessage(string topic, string message)
        {
            await mqttClientService.Publish(topic, message);

            return Ok();
        }
    }

Publish method will look like this (I added semaphore because MqttClient is not thread safe to avoid sending too many requests at a time):

        static SemaphoreSlim semaphoreSlim = new SemaphoreSlim(1, 1);

        public async Task Publish(string topic, string message)
        {
            await semaphoreSlim.WaitAsync();
            try
            {
                await mqttClient.PublishStringAsync(topic, message);
            }
            finally
            {
                //Very important to release
                semaphoreSlim.Release();
            }
        }

2. Handling state of client in the scenario above (when it is disconnected) similar question to here. I'm mentioning since there are a lot of comments in issues stating that ManagedClient is not stable so I would like to stick with low level one.

Which project is your question related to?

• Client