Understand the working principle of the Java message service framework in the Java class library

Java Message Services (JMS) is a JAVA platform -based message intermediateware specification for conveying messages in distributed systems.It provides the ability to reliably transmit asynchronous messages between different applications. Through the direct interaction between the deprived transmitter and the receiver, it realizes a highly scalable and loose -coupled distributed system architecture. In the Java class library, the JMS framework is a standard for the Java platform and implemented through a set of interfaces and classes.Before using the JMS framework, you first need to choose a JMS provider, such as Apache ActiveMQ, IBM MQ, etc., and then use the JMS API to write code according to the JMS specification. The working principle of the JMS framework mainly involves the following aspects: 1. JMS provider: JMS provider is a message queue server or message agent, responsible for managing the transmission of messages.It provides a mechanism for sending and receiving by the interfaces and classes defined in the JMS specification.JMS providers are also responsible for the storage, routing and transmission tasks of managing messages. 2. Connection Factory: Connecting the factory is an object of connecting to the establishment of connection with JMS providers.By connecting the factory, the Connection object can be created, and the connection is a communication channel between the client and the JMS provider. 3. Connection: JMS connection is a physical connection between the client and the JMS provider.The session object can be created through the JMS connection. 4. SESSION: The session is a logical connection between the client and the JMS provider for sending and receiving messages.The session provides the operation of the message, receiving, submission, and rollback.You can create message producers and MessageConsume (MESSAGEPRODER) and MessageConsumer. 5. MessageProducer: Message producers are used to send messages to the target queue or theme, and publish the message to subscribers.It can create a message (MESSAGE) object and send the message to the target position. 6. Destination: The goal is the destination of message transmission, which can be queue or topic.The queue is used for point -to -point message transmission, and only one consumer can receive each message; the theme is used to publish/subscribe to the message transmission, and each message can have multiple subscribers. 7. Message: The message is the actual data unit that contains the head and body of the message.JMS specifications define different types of messages, such as text messages, byte messages, object messages, etc. Below is a simple sample code for sending and receiving messages using the JMS framework: import javax.jms.*; import org.apache.activemq.ActiveMQConnectionFactory; public class JmsExample { public static void main(String[] args) throws JMSException { // Create a connection factory ConnectionFactory factory = new ActiveMQConnectionFactory("tcp://localhost:61616"); // Create a connection Connection connection = factory.createConnection(); connection.start(); // Create the meeting Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); // Create the target queue Queue queue = session.createQueue("test.queue"); // Create message producers MessageProducer producer = session.createProducer(queue); // Create text messages TextMessage message = session.createTextMessage("Hello, JMS!"); // Send a message producer.send(message); // Create message Consumers MessageConsumer consumer = session.createConsumer(queue); // Receive messages Message receivedMessage = consumer.receive(); if (receivedMessage instanceof TextMessage) { TextMessage textMessage = (TextMessage) receivedMessage; System.out.println("Received message: " + textMessage.getText()); } // Turn off the connection connection.close(); } } The above example code demonstrates how to use ActiveMQ as a JMS provider to send and receive messages.First create a connection factory, and then create a connection and session.Then create a target queue, message producer and message consumers, and send and receive messages.Finally close the connection. Through the JMS framework, we can easily implement the asynchronous transmission of messages in a distributed system to improve the reliability and scalability of the system.I hope this article can help you understand the working principle of the Java message service framework in the Java class library.