Module 12: Building Decoupled Architectures

Question 1

What statement describes the difference between tightly coupled architecture and loosely coupled architecture?

• Components in tightly coupled architecture are highly dependent on each other, but they are not highly dependent in a loosely coupled architecture.
• Loosely coupled architectures must use managed services, tightly coupled architectures do not have this limitation.
• Tightly coupling any part of an architecture means that the entire architecture is tightly coupled, but this principle does not apply to a loosely coupled architecture.

Tightly coupled architectures are more likely to fail than loosely coupled architectures.

Answer 1

• Components in tightly coupled architecture are highly dependent on each other, but they are not highly dependent in a loosely coupled architecture.

(The number of dependencies between components determines the level of coupling. The level of coupling is a relative judgement. An architecture that is considered loosely coupled can be more tightly coupled than an even more loosely coupled architecture.)

Question 2

Which phrases describe Amazon Simple Queue Service (Amazon SQS)? (Select THREE.)

• Sends push notifications to consumers
• Stores and encrypts messages until they are processed and deleted
• Supports email and text messaging
• Enables you to decouple and scale microservices, distributed systems and serverless applications
• Uses a pull mechanism
• Supports standard queues and last-in-first-out (LIFO) queues

Answer 2

(The answer is not the following combination:
- Stores and encrypts messages until they are processed and deleted

• Enables you to decouple and scale microservices, distributed systems and serverless applications
• Supports standard queues and last-in-first-out (LIFO) queues.

Email and text messaging are forms of push notifications. Message consumers retrieve (pull) messages from a queue instead of receiving push notifications. Amazon SQS supports standard queues and first-in-first-out (FIFO) queues- not LIFO queues.

Question 3

Which scenarios indicate that you should use an Amazon Simple Queue Service (Amazon SQS) standard queue? (Select TWO.)

• A message might need to be delivered more than once.
• Message prioritization is necessary.
• Messages must be processed in the order they are sent.
• A message must be processed only once.
• Messages can be sent in any order.

Answer 3

(The following combination is is not correct:
- A message might need to be delivered more than once.

• Messages must be processed in the order they are sent.
• or -
• Message prioritization is necessary.
• Messages can be sent in any order.

For messages that must be processed only once, and in the order they are sent, use an SQS first-in-first-out (FIFO) queue. SQS queues do not support message prioritization. Use separate queues to handle message prioritization.)

Question 4

A fleet of Amazon EC2 instances process videos that users upload. Which function can Amazon SQS perform for this application?

• An SQS queue receives messages from the application and notifies all available EC2 instances that videos are available.
• The application places job messages in an SQS queue. EC2 instances with available processing capacity pull the next video from the queue.
• The application writes the video files to an SQS queue. EC2 instances with available processing capacity pull the next video from the queue.
• EC2 instances put edited video files in an SQS queue. The application retrieves the videos from the queue.

Answer 4

• The application places job messages in an SQS queue. EC2 instances with available processing capacity pull the next video from the queue.

( The function is like people in line for the next available customer service representative. By using an SQS queue, you can send, store, and receive messages between software components at any volume, without losing messages or requiring other services to be available.)

Question 5

What is Amazon Simple Notification System (Amazon SNS)?
- A cost effective, flexible and scalable email service that enables developers to send email from within any application.

• A serverless event bus that enables easy connection of applications by using data from your own application, integrated software as a service (SaaS) applications, and AWS services.
• A fully managed messaging service for both system-to-system and application-to-person (A2P) communication, which uses publish/subscribe (pub/sub) patterns
• A flexible and scalable outbound and inbound marketing communications service that uses email, short message service (SMS), push, or voice communications channels.

Answer 5

• A fully managed messaging service for both system-to-system and application-to-person (A2P) communication, which uses publish/subscribe (pub/sub) patterns

(When you use Amazon SNS, you create topic and set policies that restrict who can publish or subscribe to the topic.)

Question 6

What are three use cases for Amazon SNS? (Select THREE)
- Gather streaming data from multiple systems.

• Notify multiple systems that user input is ready for processing.
• Trigger a single AWS Lambda function when an object is created in an Amazon S3 bucket.
• Send a push notification to mobile applications when a new software update is available.
• Send a text message to systems operators when unusual activity has been detected.

Answer 6

• Notify multiple systems that user input is ready for processing.
• Send a push notification to mobile applications when a new software update is available.
• Send a text message to systems operators when unusual activity has been detected.

( You can use Amazon SNS to communicate between systems through publish/subscribe patterns that enable messaging between decoupled microservice applicatinos. You can also use it to communicate directly to users through AWS Server Migration Service (AWS SMS), mobile push, or email.)

Question 7

What are some features of Amazon Simple Notification Service (Amazon SNS)? (Select THREE.)

• Message delivery to an Amazon SQS queue
• Recall of sent messages
• Guaranteed message delivery to a URL
• Message delivery to a URL
• Support for encryption
• Automatic message sorting by time

Answer 7

The following combination is not correct:
- Message delivery to an Amazon SQS queue

• Message delivery to a URL
• Support for encryption

(SNS topics can send messages to email addresses, HTTP(S) URLs, AWS Server Migration Service (AWS SMS) clients, SQS queues, and AWS Lambda functions. SNS topics can be encrypted by using customer master keys (CMKs) in AWS Key Management Service (AWS KMS).

Amazon SNS does not have any options to recall sent messages. Order and delivery of messages is not guaranteed. Amazon SNS attempts to deliver messages in the order that they were published. Network issues might result in messages being received out of order.)

Question 8

What is Amazon MQ?

• Managed queue service
• Message broker service
• Identity broker service
• Message query service

Answer 8

• Message broker service
  (Amazon MQ is a managed message broker service that makes it easy to set up and operate message brokers in the cloud.)

Question 9

What is a good use case for Amazon MQ?

• Connecting a virtual private cloud (VPC) to an on-premises network
• Decoupling components in a new cloud-native application
• Uploading a standalone static website to Amazon Web Services
• Migrating an existing on-premises application that uses Apache Active MQ to communicate between microservices.

Answer 9

• Migrating an existing on-premises application that uses Apache Active MQ to communicate between microservices.

( Amazon MQ reduces your operational load by managing the provisioning, setup, and maintenance of Apache ActiveMQ. Connecting your current applications to Amazon MQ is easy because it uses open standard application programming interfaces (APIs) and protocols)

Question 10

Two AWS Lambda functions must simultaneously process PDF files when they are uploaded to an Amazon S3 bucket. The S3 event notification allows only one action when the PDF files are uploaded. Which solution provides the simplest and most efficient way to trigger both Lambda functions?

• Send the S3 event to Amazon MQ for distribution to both Lambda functions.
• Send the S3 event to an Amazon SQS queue that both Lambda functions poll.
• Send the S3 event to an Amazon Simple Notification Service (Amazon SNS) topic that both Lambda functions subscribe to.

Upload two copies of each PDF file by using different object key prefixes.

Answer 10

• Send the S3 event to Amazon MQ for distribution to both Lambda functions.
  (Amazon MQ is useful when you have an existing architecture that uses Apache Active MQ, because this architecture is the new architecture that is built in AWS, native AWS service provide simpler integration.

(the correct answer is not:
- Send the S3 event to an Amazon SQS queue that both Lambda functions poll.)