Spring Cloud AWS provides Amazon SQS and Amazon SNS integration

Spring Cloud AWS provides Amazon SQS and Amazon SNS integration that simplifies the publication and consumption of messages over SQS or SNS. While SQS fully relies on the messaging API introduced with Spring 4.0, SNS only partially implements it as the receiving part must be handled differently for push notifications.

Configuring messaging

Before using and configuring the messaging support, the application has to include the respective module dependency into the Maven configuration. Spring Cloud AWS Messaging support comes as a separate module to allow the modularized use of the modules.

Maven dependency configuration

The Spring Cloud AWS messaging module comes as a standalone module and can be imported with the following dependency declaration:

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-aws-messaging</artifactId>
	<version>{spring-cloud-version}</version>
</dependency>

SQS Support

Amazon SQS is a hosted messaging service on the Amazon Web Service platform that provides point-to-point communication with queues. Compared to JMS or other message services Amazon SQS has several features and limitations that should be taken into consideration.

• Amazon SQS allows only String payloads, so any Object must be transformed into a String representation. Spring Cloud AWS has dedicated support to transfer Java objects with Amazon SQS messages by converting them to JSON.
• Amazon SQS has no transaction support, so messages might therefore be retrieved twice. The application has to be written in an idempotent way so that they can receive a message twice.
• Amazon SQS has a maximum message size of 256kb per message, so bigger messages will fail to be sent.

Sending a message

The QueueMessagingTemplate contains many convenience methods to send a message. There are send methods that specify the destination using a QueueMessageChannel object and those that specify the destination using a string which is going to be resolved against the SQS API. The send method that takes no destination argument uses the default destination.

import com.amazonaws.services.sqs.AmazonSQSAsync;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.cloud.aws.messaging.core.QueueMessagingTemplate;
import org.springframework.messaging.support.MessageBuilder;

public class SqsQueueSender {

	private final QueueMessagingTemplate queueMessagingTemplate;

	@Autowired
	public SqsQueueSender(AmazonSQSAsync amazonSqs) {
		this.queueMessagingTemplate = new QueueMessagingTemplate(amazonSqs);
	}

	public void send(String message) {
		this.queueMessagingTemplate.send("physicalQueueName", MessageBuilder.withPayload(message).build());
	}
}

This example uses the MessageBuilder class to create a message with a string payload. The QueueMessagingTemplate is constructed by passing a reference to the AmazonSQS client. The destination in the send method is a string value that must match the queue name defined on AWS. This value will be resolved at runtime by the Amazon SQS client. Optionally a ResourceIdResolver implementation can be passed to the QueueMessagingTemplate constructor to resolve resources by logical name when running inside a CloudFormation stack (see Chapter 4, Managing cloud environments for more information about resource name resolution).

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import com.amazonaws.auth.AWSStaticCredentialsProvider;
import com.amazonaws.auth.BasicAWSCredentials;
import com.amazonaws.services.sqs.AmazonSQSAsync;
import com.amazonaws.services.sqs.AmazonSQSAsyncClientBuilder;
@Configuration
public class AwsConfiguration {
@Value("${cloud.aws.credentials.access-key}")
private String awsAccessKey;
@Value("${cloud.aws.credentials.secret-key}")
private String awsSecretKey;
@Value("${cloud.aws.region.static}")
private String region;
@Bean
@Primary
public AmazonSQSAsync amazonSQSAsync() {
  return AmazonSQSAsyncClientBuilder.standard().withRegion(region)
    .withCredentials(new AWSStaticCredentialsProvider(new BasicAWSCredentials(awsAccessKey, awsSecretKey)))
    .build();
 }
}

faizakram/springboot-with-aws-sqs

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