Namespaces

The HiveMQ MQTT client library is organized into namespaces that group related functionality. This page helps you understand which namespaces to import for different use cases.

Quick Reference

For most applications, you only need these two imports:

using HiveMQtt.Client;       // Client classes and builders
using HiveMQtt.MQTT5.Types;  // QoS levels, topic filters, etc.

Namespace Reference

Core Namespaces

Namespace	Purpose	Common Classes
HiveMQtt.Client	Main client classes and builders	HiveMQClient, RawClient, HiveMQClientOptionsBuilder, SubscribeOptionsBuilder, PublishMessageBuilder
HiveMQtt.MQTT5.Types	MQTT protocol types and enums	QualityOfService, RetainHandling, TopicFilter, MQTT5PublishMessage

Additional Namespaces

Namespace	Purpose	When to Use
HiveMQtt.Client.Options	Options classes	When working directly with options classes instead of builders
HiveMQtt.Client.Results	Operation result classes	When inspecting detailed results from operations
HiveMQtt.Client.Events	Event argument classes	When creating typed event handlers
HiveMQtt.Client.Exceptions	Exception classes	When catching specific client exceptions
HiveMQtt.Client.ReasonCodes	Reason code enums	When checking specific QoS reason codes
HiveMQtt.MQTT5.Packets	Low-level packet classes	For packet-level event handling or debugging
HiveMQtt.MQTT5.ReasonCodes	Protocol-level reason codes	When checking specific MQTT reason codes

Usage Examples

Basic Publishing and Subscribing

using HiveMQtt.Client;
using HiveMQtt.MQTT5.Types;

var client = new HiveMQClient();
await client.ConnectAsync();
await client.SubscribeAsync("topic", QualityOfService.AtLeastOnceDelivery);
await client.PublishAsync("topic", "Hello!");

Working with Events

using HiveMQtt.Client;
using HiveMQtt.Client.Events;

client.OnMessageReceived += (sender, args) =>
{
    // args is OnMessageReceivedEventArgs
    Console.WriteLine(args.PublishMessage.PayloadAsString);
};

Checking Results

using HiveMQtt.Client;
using HiveMQtt.Client.Results;
using HiveMQtt.MQTT5.ReasonCodes;

var result = await client.ConnectAsync();
if (result.ReasonCode == ConnAckReasonCode.Success)
{
    Console.WriteLine("Connected successfully!");
}

Exception Handling

using HiveMQtt.Client;
using HiveMQtt.Client.Exceptions;

try
{
    await client.ConnectAsync();
}
catch (HiveMQttClientException ex)
{
    Console.WriteLine($"Client error: {ex.Message}");
}