Learn Rabbit MQ

Understanding of JMS and RabbitMQ

JMS

Java Messaging System (JMS)

Here is the typical example of JMS architecture overview.

Here is the type JMS example:

Real Time Example

Type of JMS Exchanges

There are FOUR different types of exchanges available in JMS

• Direct
• Fanout
• Headers
• Topic

##Direct Exchange

What is Direct Exchange

• This type of messages will first goto the Exchanges.
• Through Exchange, message will pass to Queue using binding key
• From Queue to consumer
• In order to bind a Queue in Exchange we have to provide a "Key"

Steps to follow to create Direct Exchange and Queue:

• First: Create a Exchange with type as Direct (ex: direct-exchange)
• Second: Create three different Queues namely "Mobile", "TV" and "AC"
• Third: Attach the created Queue in Exchange under Bindings using Add binding from this exchange with Queue Name and Routing Key.

TIP: By using this Direct Exchange Message Producer will talk to Exchange whereas Message Consumer will talk to Queue to get the message.

For Source code refer com.techstack.queue.direct package

##Fanout Exchange

What is Fanout Exchange

• This type of messages will first goto the Exchanges.
• Through Exchange, message will pass to EACH Queue which is associated with this Exchange
• From Queue to consumer
• In order to bind a Queue in Exchange we have to provide a "Key"

Typical example for Fanout Exchange is Publish-Subscribe model like Group Message or Bulk Email or other form of Group Messages.

Steps to follow to create Fanout Exchange and Queue:

• First: Create a FanoutExchange with type as Fanout (ex: fanout-exchange)
• Second: Create two different Queues namely "Mobile" and "AC"
• Third: Attach the created Queue in FanoutExchange under Bindings using Add binding from this exchange with Queue Name.

TIP: By using this Fanout Exchange Message Producer will talk to Exchange whereas Message Consumer will talk to Queue to get the message.

For Source code refer com.techstack.queue.fanout package

##Topic Exchange

What is Topic Exchange

• This type of messages will first goto the Topic Exchanges.

Steps to follow to create Topic Exchange and Queue:

• First: Create a FanoutExchange with type as Fanout (ex: fanout-exchange)
• Second: Create two different Queues namely "Mobile" and "AC"
• Third: Attach the created Queue in FanoutExchange under Bindings using Add binding from this exchange with Queue Name.

Key points:

• Producer side, message created with key separated by .(dot). For example: tv.mobile.ac
• Topic Exchange would identify those keys *.mobile.*. Which means * means eactly one word before and after the mobile.
• #.ac here # means any number of words before ac
• Here in the above diagram, TV expresion *.tv.* doesn't satisfy the TOPIC Exchange key format. Hence, message will not moved to it's Queue. Expected is tv.*.*

Some Examples about Topic Key:

TIP: By using this Topic Exchange Message Producer will talk to Exchange whereas Message Consumer will talk to Queue to get the message.

For Source code refer com.techstack.queue.topic package

##Header Exchange

What is Header Exchange

Messages with Header from Producer side will talk to HeaderExchange and based on the Exchange Header Configuration it would route the message to specific Queue based on the Header "x-match = any | all". Here any is a OR condition and all means AND condition.

For example:

• It's a key value pair from producer side.

header = {
"item1 = mobile",
"item2 = television"
}

• In the Header Exchange settings, it is configured as x-match = any which means inside the incoming message any of the key = value matched attached with this Exchange Queue, the message would route to that Queue.

Header = { "x-match = any",
           "item1 = mobile",
           "item2 =  mob"
         }

How to create a Header Exchange?

Once you created a Header Exchange in AMQP Server, you have to select the Bindings. Under the Bindings section, select Queue Name and use arguments key = value select appropriate data type

TIP: By using this Header Exchange Message Producer will talk to Exchange whereas Message Consumer will talk to Queue to get the message.

For Source code refer com.techstack.queue.headers package

Default Exchange

What is Default Exchange

Basically Default Exchange is type of Direct Exchange which doesn't have any name.
If you open RabbitMQ Exchanges tab you will see (AMQP fefault) which is of type direct.

RabbitMQ with Spring Boot

Spring Boot and RabbitMQ provides

• RabbitMQ Template - To Produce Message
• RabbitMQ Listener - To Consume Message

For Producer Example: Refer com.techstack.rabbitmq.controller.RabbitMqController#processName

Pivotal Cloud Foundry

• Cloud Foundry is an open source cloud Platform As A Service (PaaS) on which developers can build, deploy, run and scale application.
• Setting Up Pivotal Cloud Foundry and Creating Organization and CLI installation
• Creating RabbitMQ service
• Spring Boot Deployment
• Spring Boot Deployment using Spring Cloud (Dependency)

Steps to Create a RabbitMQ cloud service

• Login to your PCF Console
• Click on the Marketplace and search for "CloudAMQP" service
• Select Free Plan called "Little Lemur"
• Create a service with your "Service-Name"
• Once service instance up and running, click Manage button. It will open a Cloud AMQP.
• In the LHS you will find RabbitMQ Manager
  • Alternatively you can use Hosts information
  • It will ask you to enter username and password

References

Cloud AMQP is offering a service for RabbitMQ on Cloud. For more information refer CloudAMQP.

Integrating with Java: https://www.cloudamqp.com/docs/java.html
Someo of the usecases explained here: https://www.cloudamqp.com/docs/usecases.html