MQ tutorial | exchange (switch)

Exchange

Producer Send the message to Exchange , from Exchange Route messages to one or more Queue in （ Or throw away ）.Exchange according to Routing Key and Binding Key Route messages to Queue. Different types of Exchange Different routing rules . Message queue AMQP Version currently supports three types Exchange：

• Direct Exchange
• Topic Exchange
• Fanout Exchange

Direct Exchange

• The routing mode is based on Binding Key = Routing Key Rules for routing messages .
• Use scenarios to distinguish the same Exchange The news of .
• figure 1. Direct Exchange

Direct Exchange Respectively with Queue A and Queue B binding .Consumer It can be downloaded from Queue A Pull all pictures from （img） establish （create） news , from Queue B Pull all pictures from （img） journal （log） news .

1. Direct Exchange binding Queue：
   • Direct Exchange and Queue A Of Binding Key by  img.create.
   • Direct Exchange and Queue B Of Binding Key by  img.log.
2. Producer towards Direct Exchange Send a message ：
   • news A Of Routing Key by  img.create.
   • news B Of Routing Key by  img.log.
3. Direct Exchange according to Binding Key = Routing Key Rules for routing messages ：
   • Routing Key by  img.create  The news of A Route to Binding Key by  img.create  Of Queue A.
   • Routing Key by  img.log  The news of B Route to Binding Key by  img.log  Of Queue B.

Topic Exchange

• Routing rules match routing messages according to wildcards .
  • asterisk （*） Represents a word （ for example ：cn）.
  • Well No （#） For zero 、 One or more words , Between words through English full stop （.） Separate （ for example ：cn.zj.hz）.
• Use scenarios through Topic Distinguish between messages .
• figure 2. Topic Exchange

Topic Exchange Respectively with Queue A and Queue B binding .Consumer It can be downloaded from Queue A China pulls all China （cn） Hangzhou （hz） The file of （files）, from Queue B China pulls all China （cn） The store （store） The file of （files）.

1. Topic Exchange binding Queue：
   • Topic Exchange and Queue A Of Binding Key by  files.cn.hz.#.
   • Topic Exchange and Queue B Of Binding Key by  files.cn.*.store.
2. Producer towards Topic Exchange Send a message ：
   • news A Of Routing Key by  files.cn.hz.
   • news B Of Routing Key by  files.cn.hz.store.
   • news C Of Routing Key by  files.cn.sz.store.
3. Topic Exchange Route messages according to wildcard matching rules ：
   • Routing Key by  files.cn.hz  The news of A Route to Binding Key by  files.cn.hz.#  Of Queue A.
   • Routing Key by  files.cn.hz.store  The news of B Route to Binding Key by  files.cn.hz.#  Of Queue A and Binding Key by  files.cn.*.store  Of Queue B.
   • Routing Key by  files.cn.sz.store  The news of C Route to Binding Key by  files.cn.*.store  Of Queue B.

Fanout Exchange

• Routing rules Fanout Exchange ignore Routing Key and Binding Key Matching rules of , Post the message to all bound Queue.
• Use scenarios to broadcast messages .
• figure 3. Fanout Exchange

Fanout Exchange Post the message to all bound Queue,Consumer From all Queue Pull the same message .

1. Fanout Exchange binding Queue：Fanout Exchange and Queue A、Queue B、Queue C Of Binding Key Can be any value .
2. Producer towards Fanout Exchange Send a message ： news A Of Routing Key It can be any value .
3. Fanout Exchange Route messages to all bound Queue：Routing Key Messages with arbitrary values A Route to Binding Key For any value Queue A、Queue B、Queue C.

Reprint ： MQ course | Exchange（ Switch ） Introduce （ 6、 ... and ）