CODEWITHSUNDEEP
amazon-web-servicesaws-java-sdk
Barney
Barney

Reputation: 915

How to subscribe a SQS queue to a SNS topic in Java

When I create a new queue and subscribe it to a topic in Java, no message comes. The same via the AWS web console works fine.

I guess I have to confirm the subscription somehow, but the sns.confirmSubscription method needs a token - where shall I get it?

This is my Java code:

String queueURL = sqs.createQueue("my-queue").getQueueUrl();

sns.subscribe(myTopicARN, "sqs", queueURL);

sns.publish(myTopicARN, "{\"payload\":\"test\"}");

sqs.receiveMessage(queueURL).getMessages()
        .forEach(System.out::println);  // nothing

What am I doing wrong?

Upvotes: 7

Views: 7410

Answers (3)

pandaadb
pandaadb

Reputation: 6456

For completeness, you can subscribe an SQS queue to a SNS topic with the v2 java sdk like this:

        CreateTopicResponse topic = snsClient.createTopic(CreateTopicRequest.builder()
                .name("topic-name")
                .build());

        String topicArn = topic.topicArn();

        CreateQueueResponse
                queue
                = sqsClient.createQueue(CreateQueueRequest.builder()
                .queueName("queue-name")
                .build());

        String queueUrl = queue.queueUrl();

        GetQueueAttributesResponse
                queueAttributes
                = sqsClient.getQueueAttributes(GetQueueAttributesRequest.builder()
                .attributeNames(QueueAttributeName.QUEUE_ARN)
                .queueUrl(queueUrl)
                .build());

        String queueArn = queueAttributes.attributes().get(QueueAttributeName.QUEUE_ARN);

        snsClient.subscribe(SubscribeRequest.builder()
                .topicArn(topicArn)
                .protocol("sqs")
                .endpoint(queueArn)
                .build());

I have not tried this against actual AWS but it runs fine against localstack for testing.

Note that you must subscribe the SQS queue via its ARN not via the queueUrl.

Upvotes: 2

Bilel BM
Bilel BM

Reputation: 21

subscribing the queue to sns does not automatically create a policy to allow sns to send messages to the queue (based on my experience with sns/sqs) so you need to create the policy yourself and give permission to sns to send messages to your queue this is an example on how to do it using queue url , queue arn and topic arn

import static com.amazonaws.auth.policy.Principal.All;
import static com.amazonaws.auth.policy.Statement.Effect.Allow;
import static com.amazonaws.auth.policy.actions.SQSActions.SendMessage;
import static com.amazonaws.auth.policy.conditions.ArnCondition.ArnComparisonType.ArnEquals;

final Statement mainQueueStatements = new Statement(Allow) //imported above
        .withActions(SendMessage) //imported above
            .withPrincipals(All) //imported above
            .withResources(new Resource(queueArn)) // your queue arn
            .withConditions(
                    new Condition()
                            .withType(ArnEquals.name()) //imported above
                            .withConditionKey(SOURCE_ARN_CONDITION_KEY) //imported above
                            .withValues(topicArn) // your topic arn
            );
    final Policy mainQueuePolicy = ()
            .withId("MainQueuePolicy")
            .withStatements(mainQueueStatements);
    final HashMap<QueueAttributeName, String> attributes = new HashMap<>();
     attributes.put(QueueAttributeName.Policy.toString(), mainQueuePolicy.toJson());
    amazonSQS.setQueueAttributes(new SetQueueAttributesRequest().withAttributes(attributes).withQueueUrl(queueUrl)); // your queue url

Upvotes: 0

ttulka
ttulka

Reputation: 10882

Check this out: https://aws.amazon.com/blogs/developer/subscribing-queues-to-topics/

You should subscribe like this:

Topics.subscribeQueue(sns, sqs, myTopicARN, queueURL);

This convinient method creates a policy for the subscription to allow the topic to send messages to the queue.

Upvotes: 6

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