There are more AWS SDK examples available in the [AWS Doc SDK Examples](https://github.com/awsdocs/aws-doc-sdk-examples) GitHub repo. # Create and publish to a FIFO Amazon SNS topic using an AWS SDK Create and publish to a FIFO topic The following code examples show how to create and publish to a FIFO Amazon SNS topic. ------ #### [ Java ] **SDK for Java 2.x** There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/sns#code-examples). This example + creates an Amazon SNS FIFO topic, two Amazon SQS FIFO queues, and one Standard queue. + subscribes the queues to the topic and publishes a message to the topic. The [test](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/sns/src/test/java/com/example/sns/PriceUpdateExampleTest.java) verifies the receipt of the message to each queue. The [complete example](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/sns/src/main/java/com/example/sns/PriceUpdateExample.java) also shows the addition of access policies and deletes the resources at the end. ``` public class PriceUpdateExample { public final static SnsClient snsClient = SnsClient.create(); public final static SqsClient sqsClient = SqsClient.create(); public static void main(String[] args) { final String usage = "\n" + "Usage: " + " \n\n" + "Where:\n" + " fifoTopicName - The name of the FIFO topic that you want to create. \n\n" + " wholesaleQueueARN - The name of a SQS FIFO queue that will be created for the wholesale consumer. \n\n" + " retailQueueARN - The name of a SQS FIFO queue that will created for the retail consumer. \n\n" + " analyticsQueueARN - The name of a SQS standard queue that will be created for the analytics consumer. \n\n"; if (args.length != 4) { System.out.println(usage); System.exit(1); } final String fifoTopicName = args[0]; final String wholeSaleQueueName = args[1]; final String retailQueueName = args[2]; final String analyticsQueueName = args[3]; // For convenience, the QueueData class holds metadata about a queue: ARN, URL, // name and type. List queues = List.of( new QueueData(wholeSaleQueueName, QueueType.FIFO), new QueueData(retailQueueName, QueueType.FIFO), new QueueData(analyticsQueueName, QueueType.Standard)); // Create queues. createQueues(queues); // Create a topic. String topicARN = createFIFOTopic(fifoTopicName); // Subscribe each queue to the topic. subscribeQueues(queues, topicARN); // Allow the newly created topic to send messages to the queues. addAccessPolicyToQueuesFINAL(queues, topicARN); // Publish a sample price update message with payload. publishPriceUpdate(topicARN, "{\"product\": 214, \"price\": 79.99}", "Consumables"); // Clean up resources. deleteSubscriptions(queues); deleteQueues(queues); deleteTopic(topicARN); } public static String createFIFOTopic(String topicName) { try { // Create a FIFO topic by using the SNS service client. Map topicAttributes = Map.of( "FifoTopic", "true", "ContentBasedDeduplication", "false", "FifoThroughputScope", "MessageGroup"); CreateTopicRequest topicRequest = CreateTopicRequest.builder() .name(topicName) .attributes(topicAttributes) .build(); CreateTopicResponse response = snsClient.createTopic(topicRequest); String topicArn = response.topicArn(); System.out.println("The topic ARN is" + topicArn); return topicArn; } catch (SnsException e) { System.err.println(e.awsErrorDetails().errorMessage()); System.exit(1); } return ""; } public static void subscribeQueues(List queues, String topicARN) { queues.forEach(queue -> { SubscribeRequest subscribeRequest = SubscribeRequest.builder() .topicArn(topicARN) .endpoint(queue.queueARN) .protocol("sqs") .build(); // Subscribe to the endpoint by using the SNS service client. // Only Amazon SQS queues can receive notifications from an Amazon SNS FIFO // topic. SubscribeResponse subscribeResponse = snsClient.subscribe(subscribeRequest); System.out.println("The queue [" + queue.queueARN + "] subscribed to the topic [" + topicARN + "]"); queue.subscriptionARN = subscribeResponse.subscriptionArn(); }); } public static void publishPriceUpdate(String topicArn, String payload, String groupId) { try { // Create and publish a message that updates the wholesale price. String subject = "Price Update"; String dedupId = UUID.randomUUID().toString(); String attributeName = "business"; String attributeValue = "wholesale"; MessageAttributeValue msgAttValue = MessageAttributeValue.builder() .dataType("String") .stringValue(attributeValue) .build(); Map attributes = new HashMap<>(); attributes.put(attributeName, msgAttValue); PublishRequest pubRequest = PublishRequest.builder() .topicArn(topicArn) .subject(subject) .message(payload) .messageGroupId(groupId) .messageDeduplicationId(dedupId) .messageAttributes(attributes) .build(); final PublishResponse response = snsClient.publish(pubRequest); System.out.println(response.messageId()); System.out.println(response.sequenceNumber()); System.out.println("Message was published to " + topicArn); } catch (SnsException e) { System.err.println(e.awsErrorDetails().errorMessage()); System.exit(1); } } ``` + For API details, see the following topics in *AWS SDK for Java 2.x API Reference*. + [CreateTopic](https://docs.aws.amazon.com/goto/SdkForJavaV2/sns-2010-03-31/CreateTopic) + [Publish](https://docs.aws.amazon.com/goto/SdkForJavaV2/sns-2010-03-31/Publish) + [Subscribe](https://docs.aws.amazon.com/goto/SdkForJavaV2/sns-2010-03-31/Subscribe) ------ #### [ Python ] **SDK for Python (Boto3)** There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/sns#code-examples). Create an Amazon SNS FIFO topic, subscribe Amazon SQS FIFO and standard queues to the topic, and publish a message to the topic. ``` def usage_demo(): """Shows how to subscribe queues to a FIFO topic.""" print("-" * 88) print("Welcome to the `Subscribe queues to a FIFO topic` demo!") print("-" * 88) sns = boto3.resource("sns") sqs = boto3.resource("sqs") fifo_topic_wrapper = FifoTopicWrapper(sns) sns_wrapper = SnsWrapper(sns) prefix = "sqs-subscribe-demo-" queues = set() subscriptions = set() wholesale_queue = sqs.create_queue( QueueName=prefix + "wholesale.fifo", Attributes={ "MaximumMessageSize": str(4096), "ReceiveMessageWaitTimeSeconds": str(10), "VisibilityTimeout": str(300), "FifoQueue": str(True), "ContentBasedDeduplication": str(True), }, ) queues.add(wholesale_queue) print(f"Created FIFO queue with URL: {wholesale_queue.url}.") retail_queue = sqs.create_queue( QueueName=prefix + "retail.fifo", Attributes={ "MaximumMessageSize": str(4096), "ReceiveMessageWaitTimeSeconds": str(10), "VisibilityTimeout": str(300), "FifoQueue": str(True), "ContentBasedDeduplication": str(True), }, ) queues.add(retail_queue) print(f"Created FIFO queue with URL: {retail_queue.url}.") analytics_queue = sqs.create_queue(QueueName=prefix + "analytics", Attributes={}) queues.add(analytics_queue) print(f"Created standard queue with URL: {analytics_queue.url}.") topic = fifo_topic_wrapper.create_fifo_topic("price-updates-topic.fifo") print(f"Created FIFO topic: {topic.attributes['TopicArn']}.") for q in queues: fifo_topic_wrapper.add_access_policy(q, topic.attributes["TopicArn"]) print(f"Added access policies for topic: {topic.attributes['TopicArn']}.") for q in queues: sub = fifo_topic_wrapper.subscribe_queue_to_topic( topic, q.attributes["QueueArn"] ) subscriptions.add(sub) print(f"Subscribed queues to topic: {topic.attributes['TopicArn']}.") input("Press Enter to publish a message to the topic.") message_id = fifo_topic_wrapper.publish_price_update( topic, '{"product": 214, "price": 79.99}', "Consumables" ) print(f"Published price update with message ID: {message_id}.") # Clean up the subscriptions, queues, and topic. input("Press Enter to clean up resources.") for s in subscriptions: sns_wrapper.delete_subscription(s) sns_wrapper.delete_topic(topic) for q in queues: fifo_topic_wrapper.delete_queue(q) print(f"Deleted subscriptions, queues, and topic.") print("Thanks for watching!") print("-" * 88) class FifoTopicWrapper: """Encapsulates Amazon SNS FIFO topic and subscription functions.""" def __init__(self, sns_resource): """ :param sns_resource: A Boto3 Amazon SNS resource. """ self.sns_resource = sns_resource def create_fifo_topic(self, topic_name): """ Create a FIFO topic. Topic names must be made up of only uppercase and lowercase ASCII letters, numbers, underscores, and hyphens, and must be between 1 and 256 characters long. For a FIFO topic, the name must end with the .fifo suffix. :param topic_name: The name for the topic. :return: The new topic. """ try: topic = self.sns_resource.create_topic( Name=topic_name, Attributes={ "FifoTopic": str(True), "ContentBasedDeduplication": str(False), "FifoThroughputScope": "MessageGroup", }, ) logger.info("Created FIFO topic with name=%s.", topic_name) return topic except ClientError as error: logger.exception("Couldn't create topic with name=%s!", topic_name) raise error @staticmethod def add_access_policy(queue, topic_arn): """ Add the necessary access policy to a queue, so it can receive messages from a topic. :param queue: The queue resource. :param topic_arn: The ARN of the topic. :return: None. """ try: queue.set_attributes( Attributes={ "Policy": json.dumps( { "Version":"2012-10-17", "Statement": [ { "Sid": "test-sid", "Effect": "Allow", "Principal": {"AWS": "*"}, "Action": "SQS:SendMessage", "Resource": queue.attributes["QueueArn"], "Condition": { "ArnLike": {"aws:SourceArn": topic_arn} }, } ], } ) } ) logger.info("Added trust policy to the queue.") except ClientError as error: logger.exception("Couldn't add trust policy to the queue!") raise error @staticmethod def subscribe_queue_to_topic(topic, queue_arn): """ Subscribe a queue to a topic. :param topic: The topic resource. :param queue_arn: The ARN of the queue. :return: The subscription resource. """ try: subscription = topic.subscribe( Protocol="sqs", Endpoint=queue_arn, ) logger.info("The queue is subscribed to the topic.") return subscription except ClientError as error: logger.exception("Couldn't subscribe queue to topic!") raise error @staticmethod def publish_price_update(topic, payload, group_id): """ Compose and publish a message that updates the wholesale price. :param topic: The topic to publish to. :param payload: The message to publish. :param group_id: The group ID for the message. :return: The ID of the message. """ try: att_dict = {"business": {"DataType": "String", "StringValue": "wholesale"}} dedup_id = uuid.uuid4() response = topic.publish( Subject="Price Update", Message=payload, MessageAttributes=att_dict, MessageGroupId=group_id, MessageDeduplicationId=str(dedup_id), ) message_id = response["MessageId"] logger.info("Published message to topic %s.", topic.arn) except ClientError as error: logger.exception("Couldn't publish message to topic %s.", topic.arn) raise error return message_id @staticmethod def delete_queue(queue): """ Removes an SQS queue. When run against an AWS account, it can take up to 60 seconds before the queue is actually deleted. :param queue: The queue to delete. :return: None """ try: queue.delete() logger.info("Deleted queue with URL=%s.", queue.url) except ClientError as error: logger.exception("Couldn't delete queue with URL=%s!", queue.url) raise error ``` + For API details, see the following topics in *AWS SDK for Python (Boto3) API Reference*. + [CreateTopic](https://docs.aws.amazon.com/goto/boto3/sns-2010-03-31/CreateTopic) + [Publish](https://docs.aws.amazon.com/goto/boto3/sns-2010-03-31/Publish) + [Subscribe](https://docs.aws.amazon.com/goto/boto3/sns-2010-03-31/Subscribe) ------ #### [ SAP ABAP ] **SDK for SAP ABAP** There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/sap-abap/services/sns#code-examples). Create a FIFO topic, subscribe an Amazon SQS FIFO queue to the topic, and publish a message to an Amazon SNS topic. ``` " Creates a FIFO topic. " DATA lt_tpc_attributes TYPE /aws1/cl_snstopicattrsmap_w=>tt_topicattributesmap. DATA ls_tpc_attributes TYPE /aws1/cl_snstopicattrsmap_w=>ts_topicattributesmap_maprow. ls_tpc_attributes-key = 'FifoTopic'. ls_tpc_attributes-value = NEW /aws1/cl_snstopicattrsmap_w( iv_value = 'true' ). INSERT ls_tpc_attributes INTO TABLE lt_tpc_attributes. TRY. DATA(lo_create_result) = lo_sns->createtopic( iv_name = iv_topic_name it_attributes = lt_tpc_attributes ). DATA(lv_topic_arn) = lo_create_result->get_topicarn( ). ov_topic_arn = lv_topic_arn. " ov_topic_arn is returned for testing purposes. " MESSAGE 'FIFO topic created' TYPE 'I'. CATCH /aws1/cx_snstopiclimitexcdex. MESSAGE 'Unable to create more topics. You have reached the maximum number of topics allowed.' TYPE 'E'. ENDTRY. " Subscribes an endpoint to an Amazon Simple Notification Service (Amazon SNS) topic. " " Only Amazon Simple Queue Service (Amazon SQS) FIFO queues can be subscribed to an SNS FIFO topic. " TRY. DATA(lo_subscribe_result) = lo_sns->subscribe( iv_topicarn = lv_topic_arn iv_protocol = 'sqs' iv_endpoint = iv_queue_arn ). DATA(lv_subscription_arn) = lo_subscribe_result->get_subscriptionarn( ). ov_subscription_arn = lv_subscription_arn. " ov_subscription_arn is returned for testing purposes. " MESSAGE 'SQS queue was subscribed to SNS topic.' TYPE 'I'. CATCH /aws1/cx_snsnotfoundexception. MESSAGE 'Topic does not exist.' TYPE 'E'. CATCH /aws1/cx_snssubscriptionlmte00. MESSAGE 'Unable to create subscriptions. You have reached the maximum number of subscriptions allowed.' TYPE 'E'. ENDTRY. " Publish message to SNS topic. " TRY. DATA lt_msg_attributes TYPE /aws1/cl_snsmessageattrvalue=>tt_messageattributemap. DATA ls_msg_attributes TYPE /aws1/cl_snsmessageattrvalue=>ts_messageattributemap_maprow. ls_msg_attributes-key = 'Importance'. ls_msg_attributes-value = NEW /aws1/cl_snsmessageattrvalue( iv_datatype = 'String' iv_stringvalue = 'High' ). INSERT ls_msg_attributes INTO TABLE lt_msg_attributes. DATA(lo_result) = lo_sns->publish( iv_topicarn = lv_topic_arn iv_message = 'The price of your mobile plan has been increased from $19 to $23' iv_subject = 'Changes to mobile plan' iv_messagegroupid = 'Update-2' iv_messagededuplicationid = 'Update-2.1' it_messageattributes = lt_msg_attributes ). ov_message_id = lo_result->get_messageid( ). " ov_message_id is returned for testing purposes. " MESSAGE 'Message was published to SNS topic.' TYPE 'I'. CATCH /aws1/cx_snsnotfoundexception. MESSAGE 'Topic does not exist.' TYPE 'E'. ENDTRY. ``` + For API details, see the following topics in *AWS SDK for SAP ABAP API reference*. + [CreateTopic](https://docs.aws.amazon.com/sdk-for-sap-abap/v1/api/latest/index.html) + [Publish](https://docs.aws.amazon.com/sdk-for-sap-abap/v1/api/latest/index.html) + [Subscribe](https://docs.aws.amazon.com/sdk-for-sap-abap/v1/api/latest/index.html) ------