Previous situation The transaction log is an important part of the database and stores the history of all changes and operations in the database system to ensure that the database does not lose data due to failures (such as power outages or other failures that cause the server to crash). In PostgreSQL (hereinafter referred to […]
Tag: subscription
Component Communication in React 02 – Message Subscription and Publishing, Unsubscription and Unsubscription when Uninstalling a Component
Component Communication in React 02 – Message Subscription and Publishing, Unsubscription and Unsubscription when Uninstalling a Component 1 Introduction 1.1 Communication using props 1.2 About useEffect 2. Install pubsub-js 3. Message subscription and publishing 3.1 Simple example-1 3.2 Simple example-2 (improvement, optimization) – subscribe to messages + use messages 4. Unsubscribe 4.1 Cancel a single […]
mqtt message subscription mechanism
Implementing the MQTT protocol requires communication between the client and the server. During the communication process, there are three identities in the MQTT protocol: Publisher (Publish), Broker (server), Subscribe. Among them, the message publisher and subscriber are both clients, the message agent is the server, and the message publisher can be a subscriber at the […]
Use stompjs to implement Websocket instant messaging subscription and publishing
Instant messaging is often used in daily development to achieve real-time updates of messages. 1. Use polling for query (if the status does not change for a long time under a certain situation, the client’s frequent calling of the interface will cause a waste of resources) 2. Use websockets The following examples use stompjs and […]
About the application of Subscription in Angular development
In Angular applications, Subscription is part of the RxJS (Reactive Extensions for JavaScript) library and is used to manage subscriptions to Observables. Subscriptions are a mechanism used in reactive programming that allow us to perform actions when an observed object emits a new value. In Angular, the Subscription class is often used to handle the […]
Latest solution: Unable to read consumer identityThis system is not registered to Red Hat Subscription Managemen
In the Red Hat 8 system, the yum command installation error reports: Unable to read consumer identity This system is not registered to Red Hat Subscription Management, You can use subscription-manager to register Error reason: The Rhel system does not give you permission. If you want to install it, you need to register and pay […]
Springboot integrates mqtt to implement message subscription
? 1. What is MQTT MQTT is a client-server architecture publish/subscribe messaging protocol. Its design ideas are lightweight, open, simple, standardized, and easy to implement. These characteristics make it a good choice for many scenarios, especially for constrained environments such as machine-to-machine communication (M2M) and Internet of Things environments (IoT). 2. The main communication method […]
Write MQTT subscription program in python
Download | Eclipse Mosquitto 1. Download: https://mosquitto.org/files/binary/win64/mosquitto-2.0.17-install-windows-x64.exe 2. Installation: 3. conf configuration 1) Use notepad to open “C:\Program Files\mosquitto\mosquitto.conf” and save it as c:\myapp\msquitto\mosquitto.conf.txt listener 1883 protocol mqtt listener 9005 protocol websockets allow_anonymous true log_type notice log_type websockets log_type warning log_type error log_type information 2) Rename the txt document to conf C:\myApp\mosquitto>rename mosquitto.conf.txt mosquitto.conf 4. […]
Synology deploys RSS subscription hosting service
Article directory Synology deploys RSS subscription hosting service basic knowledge The relationship between php and apache CGI, FastCGI, PHP-FPM relationship What is CGI Introduction to FastCGI How FastCGI works PHP-FPM Prepare Install Web Station, PHP 7.3, Apache HTTP Server, MariaDB 10 Set up database remote access Add virtual host Log in to freshrss to resolve […]
Dubbo3 service release registration and subscription
Foreword Three major centers Dubbo versions before 2.7 are only equipped with a registration center, and the mainstream registration center is zookeeper. Later, version 2.7 officially carried out the transformation of three major centers, namely: registration center, metadata center, and configuration center. Metadata is defined as data that describes data. In service governance, such as […]