All docs This doc
Skip to end of metadata
Go to start of metadata

You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 8 Next »

AMQP is a wire-level messaging protocol that describes the format of the data that is sent across the network. If a system or application can read and write AMQP, it can exchange messages with any other system or application that understands AMQP, regardless of the implementation language.

The RabbitMQ AMQP transport is implemented using the RabbitMQ Java Client. It allows you to send or receive AMQP messages by calling an AMQP broker (RabbitMQ) directly, without the need to use different transport mechanisms, such as JMS. 

The following diagram illustrates a scenario where the ESB uses the RabbitMQ AMQP transport to exchange messages between RabbitMQ Java Clients by calling RabbitMQ brokers.


As you can see in the diagram, the Sender uses the RabbitMQ Java Client to publish messages to an AMQP queue (Q1), and the Receiver users it to consume messages from an AMQP queue (Q2). In this scenario, a proxy service in the ESB listens to Q1, and when a message becomes available on the queue, the proxy service consumes it and publishes it to Q2.
 

The following sections describe the process of installing the RabbitMQ AMQP transport, configuring the transport as well as using the transport by walking you through a sample RabbitMQ proxy service.



Configuring the RabbitMQ AMQP transport

  1. Open <ESB_HOME>/repository/conf/axis2/axis2.xml for editing.
  2. In the transport listeners section, add the following RabbitMQ transport listener, replacing the values with your host, port, username, and password to connect to the AMQP broker. 

    <transportReceiver name="rabbitmq" class="org.apache.axis2.transport.rabbitmq.RabbitMQListener">
       <parameter name="AMQPConnectionFactory" locked="false">
          <parameter name="rabbitmq.server.host.name" locked="false">192.168.0.3</parameter>
          <parameter name="rabbitmq.server.port" locked="false">5672</parameter>
          <parameter name="rabbitmq.server.user.name" locked="false">user</parameter>
          <parameter name="rabbitmq.server.password" locked="false">abc123</parameter>
       </parameter>
    </transportReceiver>

    As an optional step, you can create multiple connection factories if you want this listener to connect to multiple brokers.

     

  3. In the transport senders section, add the following RabbitMQ transport sender, which will be used for sending AMQP messages to a queue:

    <transportSender name="rabbitmq" class="org.apache.axis2.transport.rabbitmq.RabbitMQSender"/>
  4. Start the ESB server.

You are now ready to create the RabbitMQ proxy service.

Creating the RabbitMQ proxy service

Following is a sample RabbitMQ proxy service named AMQPProxy, which consumes AMQP messages from one RabbitMQ broker and publishes them to another:

Sample Proxy Service
<proxy xmlns="http://ws.apache.org/ns/synapse" name="AMQPProxy" transports="rabbitmq" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
         <log level="full"/>
         <property name="OUT_ONLY" value="true"/>
         <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2"/>
      </inSequence>
      <endpoint>
         <address
         uri="rabbitmq:/AMQPProxy?rabbitmq.server.host.name=192.168.0.3&rabbitmq.server.port=5672&rabbitmq.server.user.name=user&rabbitmq.server.password=abc123&rabbitmq.queue.name=queue2&rabbitmq.exchange.name=exchange2"/>
      </endpoint>
   </target>
   <parameter name="rabbitmq.queue.name">queue1</parameter>
   <parameter name="rabbitmq.exchange.name">exchange1</parameter>
   <parameter name="rabbitmq.connection.factory">AMQPConnectionFactory</parameter>
   <description></description>
</proxy>

Note the following:

  • The transport key name is rabbitmq. You need to specify this key name in the transports parameter (ie., transports="rabbitmq").
  • The proxy is defined as OUT_ONLY, because it does not expect a response from the endpoint.
  • The endpoint specifies where the messages will be published. The URI prefix is rabbbitmq so that the RabbitMQ AMQP transport will be used to publish the message. Be sure to specify the rest of the parameters in the URI as shown in the sample proxy service above. (NOTE: if you are configuring the URI through the management console instead of entering the configuration directly in the configuration file, you must encode the ampersands in the URI as "&amp;" instead of "&".) If you do not know which RabbitMQ exchange to use, leave the value blank to use the default exchange.
  • The rabbitmq.queue.name parameter specifies the queue on which the proxy service listens and consumes messages. If you do not specify a name for this parameter, the name of the proxy service will be used as the queue name.
  •  The rabbitmq.exchange.name parameter specifies the RabbitMQ exchange to which the queue is bound. If you do not want to use a specific exchange, leave this value blank to use the default exchange.
  • The rabbitmq.connection.factory parameter specifies the listener that listens on the queue and consumes messages. In this example, the connection factory is set to the name of the listener we created earlier (ie., AMQPConnectionFactory).

You can modify the sample proxy service above to handle scenarios where you only want to receive AMQP messages but need to send messages in a different format, or you want to receive messages in a different format and send only AMQP messages. You can also modify the proxy service to work with a different transport. For example, you can create a proxy that uses the RabbitMQ AMQP transport to listen to messages and then sends them over HTTP or JMS.

Sample java clients

This section describes the sample Java clients that you can use to send and receive AMQP messages. These clients can be used to test the scenario where the Sender publishes a message to a RabbitMQ AMQP queue, which is consumed by the ESB and published to another queue, which in turn is consumed by the Receiver. When you run these clients, the Receiver will get the messages sent by the Sender, confirming that you have correctly configured the RabbitMQ AMQP transport.

AMQP sender

The following Java client sends SOAP XML messages to a RabbitMQ queue:

ConnectionFactory factory = new ConnectionFactory();
factory.setHost(host);
factory.setUsername(username);
factory.setPassword(password);
factory.setPort(port);
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.queueDeclare(queueName, false, false, false, null);
channel.exchangeDeclare(exchangeName, "direct", true);
channel.queueBind(queueName, exchangeName, routingKey);

// The message to be sent
String message = "<soapenv:Envelope
                  xmlns:soapenv=\"http://schemas.xmlsoap.org/soap/envelope">\n" +  
                 "<soapenv:Header/>\n" +
                 "<soapenv:Body>\n" +
                 "  <p:greet xmlns:p=\"http://greet.service.kishanthan.org\">\n" + 
                 "     <in>" + name + "</in>\n" +
                 "  </p:greet>\n" +
                 "</soapenv:Body>\n" +
                 "</soapenv:Envelope>";

// Populate the AMQP message properties
AMQP.BasicProperties.Builder builder = new
AMQP.BasicProperties().builder();
builder.messageId(messageID);
builder.contentType("text/xml");
builder.replyTo(replyToAddress);
builder.correlationId(correlationId);
builder.contentEncoding(contentEncoding);

// Custom user properties
Map<String, Object> headers = new HashMap<String, Object>();
headers.put("SOAP_ACTION", "greet");
builder.headers(headers);

// Publish the message to exchange
channel.basicPublish(exchangeName, queueName, builder.build(), message.getBytes());

This client was tested with SOAP messages sent and consumed from AMQP broker queues with the content type “text/xml”. When specifying the queue name for publishing messages, be sure to specify the same queue where the RabbitMQ transport listener is listening.

AMQP receiver

When specifying the queue name for consuming messages, be sure to specify the same queue configured in the proxy service endpoint.

ConnectionFactory factory = new ConnectionFactory();
factory.setHost(hostName);
factory.setUsername(userName);
factory.setPassword(password);
factory.setPort(port);
Connection connection = factory.newConnection();
Channel channel = connection.createChannel();
channel.queueDeclare(queueName, false, false, false, null);
channel.exchangeDeclare(exchangeName, "direct", true);
channel.queueBind(queueName, exchangeName, routingKey);

// Create the consumer
QueueingConsumer consumer = new QueueingConsumer(channel);
channel.basicConsume(queueName, true, consumer);

// Start consuming messages
while (true) {
   QueueingConsumer.Delivery delivery = consumer.nextDelivery();
   String message = new String(delivery.getBody());
}

RabbitMQ AMQP transport parameters

Following are details on the listener parameters you can set:

ParameterDescriptionRequired

rabbitmq.connection.factory 

The name of the connection factory.

Yes

rabbitmq.exchange.name 

Name of the RabbitMQ exchange to which the queue is bound. Use this parameter instead of rabbitmq.queue.routing.key, if you need to use the default exchange and publish to a queue.

No

rabbitmq.queue.name 

The queue name to send or consume messages. If you do not specify this parameter, you need to specify the

rabbitmq.queue.routing.key parameter.

Yes

rabbitmq.queue.auto.ack 

Whether to automatically send back an acknowledgement.

No

rabbitmq.consumer.tag 

The client­ generated consumer tag to establish context.

No

rabbitmq.channel.consumer.qos 

The consumer qos value. You need to specify this parameter only if the rabbitmq.queue.auto.ack parameter is set to false

No
rabbitmq.queue.durable Whether the queue should remain declared even if the broker restarts. No

rabbitmq.queue.exclusive 

Whether the queue should be exclusive or should be consumable by other connections. No

rabbitmq.queue.auto.delete 

Whether to keep the queue even if it is not being consumed anymore. No
rabbitmq.queue.routing.keyThe routing key of the queue. No
rabbitmq.exchange.typeThe type of the exchange. No
rabbitmq.exchange.durableWhether the exchange should remain declared even if the broker restarts. No
rabbitmq.exchange.auto.deleteWhether to keep the queue even if it is not used anymore. No

 

Following are details on the sender parameters you can set:

ParameterDescriptionRequired

rabbitmq.server.host.name 

Host name of the server.Yes

rabbitmq.server.port 

Port number of the server.Yes

rabbitmq.exchange.name 

The name of the RabbitMQ exchange to which the queue is bound. Use this parameter instead of

rabbitmq.queue.routing.key, if you need to use the default exchange and publish to a queue.

No

rabbitmq.queue.routing.key 

The exchange and queue binding key that will be used to route messages.

No

rabbitmq.replyto.name 

The name of the call back­ queue. Specify this parameter if you expect a response.

No

rabbitmq.queue.delivery.mode 

The delivery mode of the queue. Possible values are 1 and 2.
1 - Non­-persistent.

2 - Persistent. This is the default value.

No

rabbitmq.exchange.type 

The type of the exchange.No

rabbitmq.queue.name 

The queue name to send or consume messages. If you do not specify this parameter, you need to specify the

rabbitmq.queue.routing.key parameter.

Yes

rabbitmq.queue.durable 

Whether the queue should remain declared even if the broker restarts. The default value is false.No

rabbitmq.queue.exclusive 

Whether the queue should be exclusive or should be consumable by other connections. The default value is false.No

rabbitmq.queue.auto.delete 

Whether to keep the queue even if it is not being consumed anymore. The default value is false.No

rabbitmq.exchange.durable 

Whether the exchange should remain declared even if the broker restarts.No

Here the rabbitmq.server properties refer to the server on which RabbitMQ is running.

SSL enabled RabbitMQ transport

To enable SSL support in RabbitMQ, you need to configure the following parameters in the listener.

ParameterDescriptionRequired
   
   
   
   

Following is a sample SSL enabled transport listener configuration:

<transportReceiver name="rabbitmq" class="org.apache.axis2.transport.rabbitmq.RabbitMQListener">					
<parameter name="AMQPConnectionFactoryKS"locked="false">
<parameter name="rabbitmq.server.host.name"locked="false">localhost</parameter>
<parameter name="rabbitmq.server.port"locked="false">5671</parameter>
<parameter name="rabbitmq.server.user.name"locked="false"></parameter>
<parameter name="rabbitmq.server.password"locked="false"></parameter>
<parameter name="rabbitmq.connection.retry.interval"locked="false">10000</parameter>
<parameter name="rabbitmq.connection.retry.count"locked="false">5</parameter>
<parameter name="rabbitmq.connection.ssl.enabled"locked="false">true</parameter>
<parameter name="rabbitmq.connection.ssl.version"locked="false">SSL</parameter>
<parameter name="rabbitmq.connection.ssl.keystore.location"locked="false">../client/keycert.p12</parameter>
<parameter name="rabbitmq.connection.ssl.keystore.type"locked="false">PKCS12</parameter>
<parameter name="rabbitmq.connection.ssl.keystore.password"locked="false">MySecretPassword</parameter>
<parameter name="rabbitmq.connection.ssl.truststore.location"locked="false">ssl/rabbitstore</parameter>
<parameter name="rabbitmq.connection.ssl.truststore.type"locked="false">JKS</parameter>
<parameter name="rabbitmq.connection.ssl.truststore.password"locked="false">rabbitstore</parameter>
</parameter> 
</transportReceiver>

 


  • No labels