Introduction to JMS and core knowledge of message middleware

JMS message service introduction and usage scenarios

• What is JMS: Java Message Service (Java Message Service), the interface for message-oriented middleware in the Java platform

• JMS is a vendor-independent API used to access messaging system messages, similar to JDBC (Java Database Connectivity). Here, JDBC is an API that can be used to access many different relational databases

• scenes to be used:

  • Core application

    • Decoupling: Order System-"Logistics System
    • Asynchronous: user registration-"send email, initialize information
    • Peak clipping: spike, log processing

  • Cross-platform, multi-language

  • Distributed transaction, eventual consistency

  • RPC calls upstream and downstream docking, data source changes -> inform subordinates

Common concepts and programming models of message middleware

• Common concepts

  • JMS provider: connection of message-oriented middleware, an implementation of JMS interface, RocketMQ, ActiveMQ, Kafka, etc.
  • JMS producer (Message Producer): a service that produces messages
  • JMS Consumer (Message Consumer): Service for consuming messages
  • JMS message: data object
  • JMS queue: the area to store messages to be consumed
  • JMS topic: a mechanism that supports sending messages to multiple subscribers
  • There are usually two types of JMS messages: Point-to-Point, Publish/Subscribe

• Basic programming model

  • Some classes needed in MQ
  • ConnectionFactory: connection factory, JMS uses it to create connections
  • Connection: JMS client to JMS Provider connection
  • Session: A thread that sends or receives messages
  • Destination: The destination of the message; to whom the message is sent.
  • MessageConsumer / MessageProducer: message consumer, message producer