JMS学习笔记之MessageBasics

发表于 2020-12-04 更新于 2020-12-28 分类于 JMS

Message Basics

Heterogeneous integration is one primary area where messaging plays a key role.

fault tolerance
load balancing
scalability
transactional support for enterprises

Desitination

queue
topic

JMS is analogous to JDBC in that application developers reuse the same API to access many different systems.

Advantage of messaging

Heterogeneous Integration
Reduce System Bottlenecks
Increase Scalability

One way to increase the scalability of a system is to add multiple concurrent message listeners to the queue

Another way to increase the overall scalability of a system is to make as much of the system asynchronous as possible.
Increase End User Productivity
Architecture Flexibility and Agility

Centralized Architectures

A message server, also called a message router or broker, is responsible for delivering messages from one messaging client to other messaging client

Decentralized Architectures

use IP multicast , no centralized server.

Messagin Model

point to point
publish subscribe

A JMS application is a business system composed of many JMSclients and generally, one JMS provider.

P2P

messages sent to a queue are received by one and only one receiver, even though there may be many receivers listening on a queue for the same message.

(Async) fire and forget
(Sync) request/reply

The point-to-point model supports load balancing, which allows multiple receivers to listen on the same queue, therefore distributing the load.

Pub/Sub

Every subscriber receives a copy of each message.

Subscribers:

Nondurable: Receive messages only when they are actively listening on the topic
Durable: will receive a copy of every message published, even if they are “offline” when the message is published.

JMS API

general API
point to point API
publish suscribe API

In general:

ConnectionFactory
Destination
Connection
Session
Message
MessageProducer
MessageConsumer

the ConnectionFactory and Destination must be obtained from the provider using JNDI (per the JMS specification).

RPC vs Async Messaging

1. Tightly Coupled RPC

RPC attempts to mimic the behavior of a system that runs in one process. When a remote procedure is invoked, the caller is blocked until the procedure completes and returns control to the caller. This synchronized model allows the developer to view the system as if it runs in one process.

2. Enterprise Messaging

JMS provides guaranteed delivery - store-and-forward