MQTT is a lightweight, publish/subscribe-based messaging protocol widely used in fields such as the Internet of Things (IoT). Below is a tutorial on using MQTT, covering basic concepts, environment setup, communication processes, and development examples: 1. Basic Concepts of MQTT1. Core Roles· Publisher: The device or application that sends messages.· Subscriber: The device or application … Read more
In web development, we are accustomed to HTTP requests, while MQTT is relatively unfamiliar.Although it is possible to use MQTT on the web, it can be quite cumbersome.We first define the topic /request as the MQTT request and /response as the MQTT response, and then combine them into a single HTTP request.1. Building an MQTT … Read more
MQTT and CoAP are commonly used lightweight communication protocols in the Internet of Things (IoT) field, and they exhibit significant differences in design goals, application scenarios, and technical characteristics. Below is a main comparison of the two: 1. Transport Layer Protocol · MQTT: Based on TCP, it provides reliable transmission and requires maintaining a long … Read more
In cross-platform Qt development, QML provides concise and powerful multimedia support, allowing for easy video playback functionality through the <span>MediaPlayer</span> and <span>VideoOutput</span> components. However, when running QML video playback applications on Linux systems (especially Ubuntu/Debian-based), users often encounter issues such as “no sound” or “unable to play”. The root cause lies in the fact that … Read more
1. Motivation Recently, while teaching an Android development course to third-year students at a vocational college, I noticed that the students primarily focused on embedded development and may not be very familiar with software development. As they are about to start their graduation projects, this series of articles aims to guide them in building a … Read more
In modern C++ cross-platform development, developers often need to write conditional compilation code based on compiler type, compiler version and target operating system. This capability is crucial for compatibility handling, performance optimization, feature enabling (such as C++11/14/17/20), and calling platform-specific APIs. This article will systematically explain how to accurately determine the compiler type, version, and … Read more
As the number of Internet of Things (IoT) devices continues to grow, the communication and connection between these devices has become an important topic of consideration. Communication is essential and critical for IoT, whether it involves short-range wireless transmission technologies or mobile communication technologies, all of which impact the development of IoT. Among these, communication … Read more
Recently, I have been busy adapting 4G modules to connect with IoT devices on Alibaba Cloud, enabling normal connections for online status, subscription, unsubscription, and publishing various functionalities. Ultimately, this is implemented in a small program that includes a power meter, where the power meter controls the module to send some commands. The Alibaba Cloud … Read more
In practical projects, when we need to implement interfaces such as “five-star rating”, “user scoring”, and “evaluation star level”, the built-in controls of Qt often cannot directly meet the requirements: they lack animation effects, styles are difficult to fully customize, and icon replacement is not flexible. To achieve a more flexible and controllable UI, we … Read more
📚 Open Source Technology DailyExploring the Infinite Possibilities of the Open Source World2025/11/17✨ Qt Abandons Direct Use of RDRAND/RDSEED to Improve Performance and Reduce ErrorsThe Qt toolkit is gradually phasing out direct reliance on the RDRAND and RDSEED instructions from the CPU for random number generation, opting instead for entropy sources provided by the operating … Read more