Which solution will meet these requirements?
Use an API Gateway integration to publish a message to an Amazon Simple Notification Service (Amazon SNS) topic when the application receives an order. Subscribe an AWS Lambda function to the topic to perform processing.
Use an API Gateway integration to send a message to an Amazon Simple Queue Service (Amazon SQS) FIFO queue when the application receives an order. Configure the SQS FIFO queue to invoke an AWS Lambda function for processing.
Use an API Gateway authorizer to block any requests while the application processes an order.
Use an API Gateway integration to send a message to an Amazon Simple Queue Service (Amazon SQS) standard queue when the application receives an order. Configure the SQS standard queue to invoke an AWS Lambda function for processing.
Explanations:
Amazon SNS does not guarantee message ordering, which is required to ensure that orders are processed in the sequence they are received.
Amazon SQS FIFO queues guarantee that messages are received and processed in the exact order they are sent, fulfilling the requirement to process orders in order.
An API Gateway authorizer controls access to the API but does not ensure order processing. It would block requests rather than ensuring they are processed sequentially.
Amazon SQS standard queues do not guarantee the order of message delivery. This option cannot meet the requirement to process orders in the sequence they are received.
I think the answer is:
Use an API Gateway integration to send a message to an Amazon Simple Queue Service (Amazon SQS) FIFO queue when the application receives an order. Configure the SQS FIFO queue to invoke an AWS Lambda function for processing.