MQ Getting Started Overview

What is the MQ?

MQ called the Message Queue, i.e. the message queue message oriented middleware. Producer to write the message in the message queue, the queue of messages consumption can be read.

It refers to the use of data exchange mechanisms for efficient and reliable messaging platform-independent and based on the data communication in distributed systems integration. Transfer and message queuing model is provided by providing a message in a distributed application environment decoupling, elastically stretchable, redundant storage, flow clipping, asynchronous communication, data synchronization.
Such a process is generally: a sender sends a message to the message server, the message stored in the message server several queue / topic in the topic, when appropriate, back to the message server forwards the message to the recipient. In this process, sending and receiving is asynchronous, that is, send no waiting, and the sender and receiver of the life cycle is not necessarily related; in particular, publish pub / subscribe under sub mode, you can also complete many of communication, that allows a message has multiple recipients.

MQ major role

1. Asynchronous: the caller without waiting for asynchronous processing;
2. Decoupling: solve the problem of calls between the coupling systems;
3. Consumers peak: to withstand peak flow, protecting the main business;

MQ advantages and disadvantages

advantage:

1. Asynchronous processing mode: a message sender can send a message without waiting for the response. Message sender to send a message to a virtual channel (topic or queue) on; the message recipient or subscribe to love listening to the channel. A message may eventually forwarded to one or more of the message recipient, the recipient of these messages are synchronized without having to make a response to the message sender. The entire process is asynchronous;

2. Decoupling between the application sender and receiver do not have to understand each other, only an acknowledgment message. The sender and receiver need not be online at the same time.

3. Available for clipping on high-traffic, to ensure the smooth operation of the system.

Disadvantages:

1. Reduce system availability, in general, the more external dependencies introduced, the more vulnerable the system, each dependency problem will cause the entire link business problems;
2. Increase the complexity of the system, to consider the various situations, for example, loss idempotency message, message, and other consumer sequence;
3. Distributed things, data consistency problems;

Comparison of various types of MQ

MQ is just a concept, the idea of ​​flying in the sky, there must be ground to achieve. Whether Which messaging middleware, has the following technical dimensions:

Technical Dimensions	ActiveMQ	RocketMQ	RabbitMQ	Kafka
PRODUCER-CUMSUMER	stand by	stand by	stand by	stand by
PUBLISH-SUBSCRIBE	stand by	stand by	stand by	stand by
REQUEST-REPLY	stand by	stand by	stand by	*
API integrity	high	(Static configuration)	high	high
Document Integrity	high	in	high	high
Multi-language support	Support, Java priority	stand by	Language-independent	Support, Java priority
Stand-alone Throughput	Ten thousand	Ten thousand	Ten thousand	One hundred thousand
Message delay	*	*	Microsecond	Millisecond
Availability	High (master-slave)	high	High (master-slave)	Very high (Distributed
Message loss	*	*	low	In theory, will not be lost
Repeat message	*	*	Controllable	In theory there will be repeated
Getting Started	Have	no	Have	Have
First deployment difficulty	*	high	low	in
Programming language	Java	Java	erlang	scala
Applications	Small and medium sized projects	Large-scale projects, clusters	In large-scale projects	Big Data