• How to achieve stable interaction with millions of online class messages?


    Ckafka helps Tencent classroom to realize stable interaction of millions of messages Introduction: during the epidemic period, in order to ensure the normal learning progress of domestic students, Tencent classroom actively responded to the call of the state to “stop work and keep learning”, and launched a special “teacher’s fast version” during the epidemic period […]

  • Kafka principle


    1. Kafka profile After unpacking the Kafka installation package, in the conf directory, server.properties #The global unique number of the broker, which cannot be repeated in the Kafka cluster, is an integer number broker.id=0 #Enable the delete topic function delete.topic.enable=true #Number of threads processing network requests num.network.threads=3 #Off the shelf quantity used to process disk […]

  • Kafka API use


    1. Producer API Introducing dependency <dependency> <groupId>org.apache.kafka</groupId> <artifactId>kafka-clients</artifactId> < version > < / version > // version </dependency> The configuration items of the producer are described in the producerconfig class, and each configuration has a corresponding doc description. The producer uses the API with the callback function demo, and also runs in blocking […]

  • Introduction to mqtt server


    Mqtt publish and subscribe mode Mqtt is based onPublish / subscribeMode for communication and data exchange with httpRequest / responseThere are essential differences. SubscriberWill go toMessage server (broker)Subscribe to oneTopic。 After a successful subscription, the message server forwards the messages under the topic to all subscribers. Topics use ‘/’ as a separator to distinguish different […]

  • Multi room and multi process chat room based on node + socket.io + redis


    1、 Related technology introduction: Message real-time push refers to push messages to the browser in real time. Users can get the latest messages in real time without refreshing the browser. The same is true for the technical principle of real-time chat room. In order to implement push technology, traditional web sites use polling technology. This […]

  • Kafka message specification


    As a message queue, Kafka has its own message format. The message in Kafka adopts bytebuf, which is a tight binary storage format because it can save a lot of space. After all, if you use the format of Java class to define message objects, you will waste a lot of space (in addition to […]

  • Realize the real-time statistics of massive billions of data by Flink


    background Message report is mainly used to count the distribution of message tasks. For example, the total number of APP users who send a single push message, the number of successfully pushed mobile phones, and how many app users click the pop-up notification and open the app, etc. Through the message report, we can directly […]

  • Winfrom: a method to reduce redraw flicker of control


    Double buffering of WinForm controls. The double buffered property of the control is hidden and its property value can be changed by reflection. Lv. Gettype(). Getproperty (“doublebeuffered”, bindingflags. Instance | bindingflags. Nonpublic). SetValue (LV, true, null); // LV is the control name   Turn on double buffering when redrawing a control. this.SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | […]

  • Detailed explanation of rocketmq’s architecture design, key features, and application scenarios


    Content outline: Introduction and evolution of rocketmq The architecture design of rocketmq Key features of rocketmq Application scenario of rocketmq Introduction to rocketmq Rocketmq is a pure Java, distributed, queue model open-source message middleware, formerly known as metaq, which is a queue model message middleware developed by Ali. After that, rocketmq became the top open-source […]

  • Kafka file storage mechanism


    1、 Storage file structure topic: can be understood as the name of a message queue partitionTo achieve scalability, a very large topic can be distributed to multiple brokers (i.e. servers), and a topic can be divided into multiple partitions, each of which is an orderly queue segment: partition is physically composed of multiple segments message: […]

  • Use timer and observer mode of C ා to complete alarm push demand


    Preface In the past two days, I interviewed a senior R & D company of Internet of things. The interview questions are as follows: Company leaders, department heads, group leaders and members are at level 4. If there is an early warning of epidemic situation, inform the group members (for individuals, there is mainly one […]

  • Kafka replica and ISR design (I)


    In Kafka, a partition log is actually a backup log. Kafka uses multiple identical backup logs to improve system availability. These backup logs are actually called replicas. Kafka’s replica can be divided into leader replica and follower replica. Leader replica provides client with read-write request. Follower replica is only used to passively synchronize data from […]