## Sender Class
In this class we will create a connection with RabbitMQ and a channel to which the message will be sent.
Create Class `Sender`
```java
package com.marcin;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import java.io.IOException;
import java.util.concurrent.TimeoutException;
public class Sender {
public static void main(String[] args) throws IOException, TimeoutException {
ConnectionFactory factory = new ConnectionFactory();
try (Connection connection = factory.newConnection()) {
Channel channel = connection.createChannel();
channel.queueDeclare("Rabbit in Jlabs", false, false, false, null);
String message = "Send something";
channel.basicPublish("", "Rabbit in Jlabs", false,null, message.getBytes());
System.out.println("Done");
}
}
}
```
At the beginning we created factory which gives connection to RabbitMQ:
```java
ConnectionFactory factory = new ConnectionFactory();
```
If you want to send or consume message you need a channel:
```java
Channel channel = connection.createChannel();
```
Next we create queue on the RabbitMQ server:
> _Our queue has name Rabbit in Jlabs_
```java
channel.queueDeclare("Rabbit in Jlabs", false, false, false, null);
```
Time to create a message:
```java
String message = "Creepy Message";
```
And we want to publish message to the queue:
```java
channel.basicPublish("", "Rabbit in Jlabs", false,null, message.getBytes());
```
Run code and check it is finished without errors.
## Find your message in queue
Go to your RabbitMQ path e.g.:
```java
c:\Program Files\RabbitMQ Server\rabbitmq_server-3.8.2\sbin
```
And in cmd run:
```java
>rabbitmqctl list_queues
```
As response you can see your queue name and number of messages:
```java
Timeout: 60.0 seconds ...
Listing queues for vhost / ...
name messages
Rabbit in Jlabs 1
```
You can run again `Sender.java` and check `rabbitmqctl list_queues`:
```java
Timeout: 60.0 seconds ...
Listing queues for vhost / ...
name messages
Rabbit in Jlabs 2
```
Now your queue contains two messages. How to check the message body?
Unfortunately you can't check this with cmd, but you can go to RabbitMQ Management Plugin (installed in first part). Go to `Queues` tab scroll down to `Get messages` and click button `Get Message(s)`. You can see your `Payload`:
## Consume message from queue
We want read our message from the queue. In this part we will create a consumer who can do it.
```java
package com.marcin;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;
import java.io.IOException;
import java.util.concurrent.TimeoutException;
public class Consumer {
public static void main(String[] args) throws IOException, TimeoutException {
ConnectionFactory factory = new ConnectionFactory();
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.queueDeclare("Rabbit in Jlabs", false, false, false, null);
channel.basicConsume("Rabbit in Jlabs",true, (consumerTag, message) -> {
String receivedMessage = new String(message.getBody(), "UTF-8");
System.out.println("Received message: " + receivedMessage);
}, consumerTag -> {});
}
}
```
Same as for `Sender` you need a channel:
```java
Channel channel = connection.createChannel();
```
And queue:
```java
channel.queueDeclare("Rabbit in Jlabs", false, false, false, null);
```
We need to convert the bytes array to a string and set encoding to UTF-8.
```java
channel.basicConsume("Rabbit in Jlabs",true, (consumerTag, message) -> {
String receivedMessage = new String(message.getBody(), "UTF-8");
System.out.println("Received message: " + receivedMessage);
```
Consumer Tag is a tag you get from the server when you connect and identifies you as a consumer:
```java
}, consumerTag -> {});
```
## Summary
Message broker is really helps in scaling your application. You can delegate work to background processes and get easier managing communication between services or applications. Message brokers gives your applications platform to send and receive messages. Provide the ability to connect with other systems and helps to create it scalable.
### Useful links
[https://www.rabbitmq.com/](https://www.rabbitmq.com/)
[http://maven.apache.org/download.cgi](http://maven.apache.org/download.cgi)
[http://maven.apache.org/guides/getting-started/maven-in-five-minutes.html](http://maven.apache.org/guides/getting-started/maven-in-five-minutes.html)
[https://mvnrepository.com/](https://mvnrepository.com/)
[https://www.erlang.org/](https://www.erlang.org/)
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