Background Previously, we discussed how to publish messages and their corresponding packets; now let’s look at how the packets for subscribing to a topic are structured. SUBSCRIBE – Subscribe to a Topic The client sends a SUBSCRIBE packet to the server to create one or more subscriptions. Each subscription registers one or more topics of … Read more
Data packets sent by IoT smart devices must be encapsulated by the corresponding protocol at each layer. With the rapid development of Internet of Things (IoT) technology, most smart devices’ communication modules support various network communication protocols such as TCP, UDP, MQTT, CoAP, HTTP, and LwM2M, which include both transport layer and application layer protocols, … Read more
MQTT Packet Structure In the MQTT protocol, an MQTT packet consists of three parts: Fixed Header, Variable Header, and Payload. (1) Fixed Header. Present in all MQTT packets, indicating the packet type and group class identifier. (2) Variable Header. Present in some MQTT packets, the packet type determines whether the variable header exists and its … Read more
Background From this chapter onwards, unless otherwise specified, the version of MQTT referred to in this article is 3.1.1. The MQTT protocol is one of the commonly used protocols in the Internet of Things, known as a “lightweight IoT messaging protocol”. MQTT and HTTP both belong to the seventh layer (application layer). For friends who … Read more
1. Introduction MQTT, which stands for Message Queuing Telemetry Transport, is an ISO standard (ISO/IEC PRF 20922) based on the publish/subscribe paradigm. It was released by IBM. Due to its lightweight, simple, open, and easy-to-implement characteristics, it is very suitable for IoT scenarios that require low power consumption and limited network bandwidth, such as remote … Read more
Click the “Blue WeChat Name” Under the Title to Quickly Follow Networking issues are relatively specialized, but understanding some basic knowledge can be very helpful in troubleshooting simple problems. This article from the technical community, “Illustration of 60 Basic Networking Knowledge Points”, explains some basic knowledge related to networks that can be learned and understood. … Read more
From: Juejin, Author: Ruheng Link: https://juejin.im/post/6844903490595061767 1. TCP/IP Model The TCP/IP protocol model (Transmission Control Protocol/Internet Protocol) includes a series of network protocols that form the foundation of the Internet and is the core protocol of the Internet. The reference model based on TCP/IP divides the protocols into four layers: the Link Layer, Network Layer, … Read more
What is a Communication Network There is a network surrounding us at all times, such as telephone networks, telegraph networks, television networks, computer networks, etc.; even within our bodies, there are many network systems, such as the nervous system and the digestive system. The most typical example is the computer network, which is a combination … Read more
[Question:] What exactly are the three protocols: NetBEUI, IPX/SPX, and TCP/IP? Especially the first two, sometimes they are installed and sometimes not. Why is that? What are the differences and unique features? When must they be installed? [Answer:] Many users have asked this question. Here, I have researched and compiled relevant information to provide a … Read more
In computer networks, to share resources and exchange data in an orderly manner, some pre-agreed rules must be followed. These standards or agreements established for data exchange in the network are called network protocols, abbreviated as protocols. To enable efficient transmission between computers, a layered approach is adopted, similar to how people collaborate to complete … Read more