Getting started with JMS (1)-Basic JMS

1. Basic concepts of JMS

Java Message Service (JMS) is a Java Message Service. It provides standard interfaces for generating, sending, and receiving messages, simplifying the development of enterprise applications. It supports two message communication models: point-to-point (P2P) model and pub/Sub Model. The P2P model specifies that a message can only have one receiver; pub/sub
The model allows a message to have multiple receivers.
For point-to-point modelsAfter the message producer generates a message, the message is sent to a queue, and then the Message Receiver reads the message from the queue. Once the message is read by a receiver, it disappears in this queue, so a message can only be consumed by one receiver.
Different from the point-to-point model,Publish/subscribe ModelWhen a message producer generates a message and sends it to a topic, the topic can have multiple receivers listening at the same time. When a message arrives at this topic, all message recipients will receive the message.

Summary:In short, the difference between the point-to-point model and the publish/subscribe model is that the former is one-to-one, and the latter is one-to-many.

2. Several Important Concepts

1) destination: the destination of the message, that is, the queue and topic mentioned above. After a message is created, you only need to send the message to the destination, and the message sender can continue to do his/her own work without waiting for the message to be processed. When the message will be consumed by the consumer depends on the message recipient.

2) message: it can be seen from the literal that the message is sent. It has the following types:
A) streammessage: Java data stream message, which is sequentially filled and read by standard stream operations.
B) mapmessage: a message of the map type. Its name is of the string type, and its value is of the basic type of Java.
C) textmessage: A common string message that contains a string.
D) objectmessage: Object message, which contains a serializable Java object
E) bytesmessage: a binary array message that contains a byte [].
F) xmlmessage: an XML message.
Note: textmessage and objectmessage are commonly used.

3) Session: The session established with the JMS provider, through which we can create a message.
4) connection: A Connection established with the JMS provider. You can create a session from this connection, that is, session.
5) connectionfactory: how to create a connection? This requires the connectionfactory mentioned below. Through this factory class, you can get a connection with the JMS provider, that is, conection. 6) Producer: the producer of a message. To send a message, it must be sent by the producer.
7) messageconsumer: corresponds to the producer, which is the consumer or receiver of the message. It is used to receive a message.
The JMS provider has been mentioned many times before, because JMS only provides a series of interfaces. When we use a JMS, we still need a third-party provider, it is used to manage these connections, sessions, topics, and queue.

The following figure shows the relationship between these concepts.

Connectionfactory ----> connection ---> session ---> message
Destination + session ------------------------------------> producer
Destination + session ------------------------------------> messageconsumer
 
Someone may ask: Where can I get connectionfactory and destination?
This is related to the JMS provider. if it is in a javaee environment, it can be found through JNDI. If it is in a non-javaee environment, it can only be obtained through the interface provided to us by the JMS provider.
About JMS entry knowledge from: http://blog.csdn.net/zhangxs_3/article/category/625599