ActiveMQ knowledge summary of Message Oriented Middleware

1、JMS（Java Message Service,Java Message service ）

1.1 Definition

Java Message service （Java Message Service, namely JMS） The API is a Java About message-oriented middleware in the platform (MOM) Of API, Used between two applications , Or send a message in a distributed system , Asynchronous communication .Java Message service is a platform independent APl.

1.2 JMS Object model of

name	describe
ConnectionFactory	Connection factory
Connection	Connect
Session	conversation
Destination	Purpose
MessageProducer	producer
MessageConsumer	consumer
Message	news
Broker	Examples of Message Oriented Middleware (ActiveMQ)

1.3 JMS Message model

1. Point-to-Point (P2P) / Point to point

   

2. Publish/Subscribe (Pub/Sub) / The theme ( Publish subscribe )

   

1.4 JMS Message structure of

The message header 、 Message properties 、 Message body

1. The message header

   

2. Message properties ： It can be understood as an additional header of the message , Attribute names can be customized

   

3. Message body

   

2、ActiveMQ Concept

2.1 Definition

ActiveMQ yes Apache Produce , One of the most popular , Powerful open source message bus .

ActiveMQ Is a full support JMS1.1 and J2EE 1.4 canonical JMS Provider Realization , Even though JMS It's been a long time since the standard was issued , however JMS In today's J2EE Application still plays a special role .

2.2 characteristic

1. Support for multiple programming languages
2. Support multiple transport protocols
3. There are many ways to persist

2.3 ActiveMQ Which protocols are supported

1. ActiveMQ Support multiple protocol transmission and transmission modes , Allow clients to connect using multiple protocols .
2. ActiveMQ Supported protocols : AUTO、 OpenWire、 AMQP、Stomp、 MQTT etc. .
3. ActiveMQ Supported basic transmission mode : VM、 TCP、SSL、 UDP 、Peer、 Multicast、 HTTP(S) etc. , And more advanced Failover、Fanout、 Discovery、 ZeroConf The way .

2.4 OpenWire agreement

2.4.1 OpenWire What is the protocol

OpenWire yes Apache A cross language protocol , Allow access to... From different languages and platforms ActiveMQ, yes ActiveMQ 4.x The default transport protocol for later versions .

2.4.2 OpenWire How the protocol is used

OpenWire Support TCP、SSL、 NIO、UDP、VM And other transmission modes , Configure these connections directly , It is used OpenWire agreement ,OpenWire Yes Own configuration parameters , The parameter names configured on the client side and the server side are all through the prefix “wireFormat.” Express .

Example

OpenWire Description of configuration parameters

attribute	The default value is	describe
stackTraceEnabled	true	Whether the stack exception that has occurred and tracked should be , adopt Broker Send to client
tcpNoDelayEnabled	true	socket Of NoDelay Parameters
cacheEnabled	true	If repeated values are cached , So as to reduce the number of groups ( The upcoming sending ) happen
tightEncodingEnabled	true	according to CPU usage , Automatically resize transmitted content ( Compression ratio )
prefixPacketSize	true	Before each packet is grouped ( To be sent soon ), Whether the size of each packet should be used as the maximum idle time of prefix connection , In Milliseconds .
maxInactivityDuration	30000	broker The service will close the timeout connection according to the configuration . At the same time, the connection can also be maintained through the heartbeat mechanism . value <=0 Disable monitoring of active connections .
maxlnactivityDurationInitalDelay	10000	After the connection is established , How soon to start timeout detection
cacheSize	1024	If it can be cached , So this specifies the maximum number of caches . In this attribute, the ActiveMQ Of 4.1 Start adding the maximum frame size that can be sent
maxFrameSize	MAX_ LONG	Can help prevent OOM DOS attack

2.5 Why use MQTT agreement

MQTT Its structure is simple , Compared with other message protocols , It's more lightweight . Suitable when the computing power is limited 、 Low bandwidth 、 Unreliable network environment use .

2.5.1 MQTT Publish subscribe model

2.5.2 MQTT Service quality

Service quality (QoS) Level is a guarantee protocol for the delivery of information between the sender and the receiver .MQTT There are three QoS Level :

1. One more time (0)
2. At least once (1)
3. For once (2)

QoS yes MQTT One of the main functions of , It makes it easier to communicate in an unreliable network , Because even in a very unreliable network , The protocol can also control whether the message needs to be retransmitted and ensure that the message arrives . It can also help clients choose freely according to the network environment and program logic QoS.

2.5.3 ActiveMQ How to use MQTT agreement

ActiveMQ Server side configuration

<transportConnectors>
	<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
	<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&wireFormat.maxFrameSize= 104857600"/>
</transportConnectors>

MQTT Configuration parameter description

attribute	The default value is	describe
maxFrameSize	268435456	(v5.12.0) Maximum frame size that can be sent . The agreement is limited to 256MB, Its value cannot be set higher . Can help prevent OOM DOS attack

Configuration example

<transportConnector name="mqtt" uri="mtt://localhost:1883?wireFormat.maxFrameSize=100000"/>

MQTT Use NIO

<transportConnector name="mgtt+nio" uri="mtt+nio://localhost:1883"/>

MQTT Use NIO + SSL

<transportConnector name="mqtt+nio" uri="mqtt+niossl://localhost:1883"/>

2.5.4 Spring Use MQTT

Spring Integration Provides MQTT Protocol support , adopt Maven Add dependencies to use .

<dependency>
    <groupld>org.springframework.integration</groupld>
    <artifactld>spring-integration-mqtt</artifactld>
    <version>5.1.1.RELEASE</version>
</dependency>

2.6 AUTO What is the protocol

AUTO Automatic detection protocol from ActiveMQ 5.13.0 Start ,ActiveMQ Start to support protocol format detection , Can automatically detect OpenWire、STOMP、 AMQP and MQTT. Allow this 4 Two types of clients share a transport

AUTO Use TCP

<transportConnector name="auto" uri="auto://localhost:5671"/>

---

AUTO Use SSL

<transportConnector name="auto+ssl" uri="autssl://localhost:5671"/>

---

AUTO Use NIO

<transportConnector name="auto+nio" uri="auto+nio://localhost:5671"/>

AUTO Use NIO+SSL

<transportConnector name="auto+nio+ssl" uri="auto+nioss://localhost:5671"/>

3、ActiveMQ High availability cluster solution

3.1 ActiveMQ What are the cluster deployment methods

Master-Slave Deployment way	Broker-Cluster Deployment way	Master-Slave And Broker-Cluster Combined deployment mode

3.2 Master-Slave Deployment way

Share the same file system

Share the same database

3.3 Broker-Cluster Deployment way

3.4 Master-Slave And Broker-Cluster Combined deployment mode

4、ActiveMQ Persistence mechanism

4.1 Queue Type of persistence mechanism

4.2 Topic Type of persistence mechanism

4.3 storage

4.3.1 JDBC The way

Store the message in the database , for example : Mysql、 SQL Server、Oracle、 DB2 etc.

advantage	shortcoming
Easy to manage	Low performance
Can support strong consistency	/

4.3.2 AMQ The way

File based storage , It has the characteristics of fast write speed and easy recovery , But because it takes too long to rebuild the index , And the index file takes up too much disk space , So it is not recommended to use .

advantage	shortcoming
Performance is higher than JDBC	Index takes up a large amount of disk space
/	Rebuilding the index is very slow

4.3.3 LevelDB The way

LevelDB yes Google Developed a set of high-performance class libraries for persistent data .LevelDB It's not a - Services , Users need to implement Server. It's a single process service , Capable of handling billions of scale Key-Value Type data , It takes up little memory .

characteristic

1. be based on K-V Storage
2. Key Values are stored in order
3. The operation interface is simple
4. Support data snapshot
5. Support data compression

L evelDB Structure

ActiveMQ To configure LevelDB： Modify the configuration file ${ACTIVEMQ_ HOME}/conf/activemq.xml

<persistenceAdapter>
	<levelDB directory="${activemq.data}/activemq-data"/>
</persistenceAdapter>

5、ActiveMQ Transaction implementation mechanism

ActiveMQ Transactions achieve ultimate consistency

The producer side implementation mechanism is as follows ：

The implementation mechanism of the consumer side is as follows ：