Your company manages a high-end auctioning site. The members register their products with the company and manage the actions related to the products. The application is built using NodeJS and MongoDB. It also uses the Redis to cache the current auctioning data and pub/sub to distribute the auction-related events like bidding count and price fluctuations.

Answer options:

A.Use the Simple Queue Service (SQS) standard queue.
B.Use the Simple Notification Service (SNS), which is similar to the Redis pub/sub, but automatically supports unlimited messages and scales.
C.Create and use the Simple Notification Service (SNS) FIFO queue.
D.Use the Simple Queue Service (SQS) FIFO queue and migrate the bid processing module to the Lambda.
E.Configure a message group identifier to represent a distinct ordered message group within the FIFO queue.

Correct Answers: D and E
Option A is INCORRECT because in the Standard queue the order is not preserved.
Option B is INCORRECT because SNS is mainly used to fan out the messages to multiple consumers. It delivers the same message to multiple consumers and does not guarantee unique message delivery.
Option C is INCORRECT because SNS does not have a FIFO queue. After all, it is a notification service (not a queueing service).
Option D is CORRECT because AWS Lambda can be configured to process the messages from the SQS FIFO queue. Lambda is serverless and cost-efficient. See more info here: https://aws.amazon.com/blogs/compute/new-for-aws-lambda-sqs-fifo-as-an-event-source/
Option E is CORRECT because, for an SQS FIFO queue, all the messages with the same Message Group Identifier will be delivered in order. Messages with different message group ID values might be sent and received out of order.