Tips and Tricks

Logging

It is recommended to disable logging (Global logger or custom logger) which running in a live environment because it adds a huge overhead to message processing. It should be avoided to attach to the global MQTTnet logger at all because an already attached method (which may not process the entry further on) leads to generation of log messages internally.

Prefer builders

MQTTnet comes with some builders like the MqttClientOptionsBuilder or MqttApplicationMessageBuilder which are supporting a fluent API. Also these builders are used to achieve version compatibility. It is supported to change the MqttClientOptions class directly but this file may have breaking changes across versions of MQTTnet. The builders instead will usually provide backward compatibility (when possible).

MQTT best practices

This project only covers the implementation of a basic MQTT library. For best practices, general recommendation and specifications please visit https://www.hivemq.com/mqtt/. A small section on MQTT topics is avaiable in the wiki under https://github.com/chkr1011/MQTTnet/wiki/MQTT-topics, too.

Prevent processing event published by server

The server (broker) does not distinguish between clients and itself. Every message is treated the same way. But it is supported to skip events from the server itself by checking the ClientId property. If this is set to null the message was sent by the server directly and processing can be skipped.

Windows IoT Core and UWP localhost loopback addresses

In Windows IoT Core as well as in UWP, loopback connections (127.0.0.1) are not allowed. If you try to connect to a locally running server (broker), this will fail.

Special notice for using the server project in Android

Under Android, there is an issue with the default bound IP address. So you have to use the actual address of the device. Check the example below.

IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];

var server = new MqttFactory().CreateMqttServer();
server.StartAsync(new MqttServerOptionsBuilder()
    .WithDefaultEndpointBoundIPAddress(ipAddress)
    .WithDefaultEndpointBoundIPV6Address(IPAddress.None)
    .Build()).GetAwaiter().GetResult();