咨询：Qt MQTT包是否提供便捷开发自定义MQTT Broker的方式？

Hey there, let's cut to the chase: the Qt MQTT module does NOT offer any built-in tools or straightforward pathways to develop a custom MQTT broker.

From what you've already noticed in the docs, classes, and examples—this module is 100% focused on client-side functionality. Every core component, like QMqttClient, QMqttSubscription, or QMqttTopic, exists solely to let you connect to an existing broker, subscribe to topics, publish messages, and handle client-side events. There are zero classes or APIs designed to handle broker responsibilities like managing client connections, routing messages between subscribers, or enforcing access control.

All official Qt MQTT examples reinforce this: they're all client demos that rely on public online brokers (like test.mosquitto.org) to showcase how the client works. You won't find any sample code that implements even a basic broker.

If you need a custom broker for your project, here are a few practical alternatives to consider:

• Roll your own with Qt Network: You can build a broker from scratch using Qt's QTcpServer and QTcpSocket for network handling, then implement the MQTT protocol spec (3.1.1 or 5.0) yourself. This gives you full control, but it requires a solid understanding of MQTT's inner workings.
• Integrate a third-party broker library: Use established open-source MQTT broker libraries (like libmosquitto's broker component, or the EMQX core) and wrap them in Qt's C++ environment. This lets you leverage existing, battle-tested broker logic without starting from zero.
• Use a pre-built open-source broker: If your use case allows it, skip building a custom broker entirely. Deploy a mature open-source option like Mosquitto or EMQX, then use Qt's MQTT client to interact with it. This is often the fastest and most reliable approach.

内容的提问来源于stack exchange，提问作者vsz