FIFO 主題的代碼範例

此範例

測試可驗證每個佇列的訊息接收狀況。完整範例也會顯示存取政策的新增，並在最後刪除資源。

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: " +
                "    <topicName> <wholesaleQueueFifoName> <retailQueueFifoName> <analyticsQueueName>\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<QueueData> 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<String, String> topicAttributes = Map.of(
                    "FifoTopic", "true",
                    "ContentBasedDeduplication", "false");

            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<QueueData> 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<String, MessageAttributeValue> 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);
        }
    }

建立 Amazon SNS FIFO 主題，訂閱 Amazon SQS FIFO 和標準佇列到該主題，並向該主題發布訊息。

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),
                },
            )
            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

建立 FIFO 主題、將 Amazon SQS FIFO 佇列訂閱至主題，然後將訊息發佈至 Amazon SNS 主題。

    " 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.