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AWS Certified Solutions Architect Exam Guide – Chapter-8

April 29, 2021 comments off

Know how to use Amazon SQS.
Amazon SQS is unique service designed by Amazon to help you to decouple your infrastructure. Using Amazon SQS, you can store messages on reliable and scalable infrastructure as they travel between your servers. This allows you to move data between distributed components of your applications that perform different tasks without losing messages or requiring each component always to be available.

Understand Amazon SQS visibility timeouts.
Visibility timeout is a period of time during which Amazon SQS prevents other components from receiving and processing a message because another component is already processing it. By default, the message visibility timeout is set to 30 seconds, and the maximum that it can be is 12 hours.

Know how to use Amazon SQS long polling.
Long polling allows your Amazon SQS client to poll an Amazon SQS queue. If nothing is there, ReceiveMessage waits between 1 and 20 seconds. If a message arrives in that time, it is returned to the caller as soon as possible. If a message does not arrive in that time, you need to execute the ReceiveMessage function again. This helps you avoid polling in tight loops and prevents you from burning through CPU cycles, keeping costs low.

Know how to use Amazon SWF.
Amazon SWF allows you to make applications that coordinate work across distributed components. Amazon SWF is driven by tasks, which are logical units of work that part of your application performs. To manage tasks across your application, you need to be aware of inter-task dependencies, scheduling of tasks, and using tasks concurrently. This is where Amazon SWF can help you. It gives you full control over implementing tasks and coordinating them without worrying about underlying complexities such as tracking their progress and maintaining their state.

Know the basics of an Amazon SWF workflow.
A workflow is a collection of activities (coordinated by login) that carry out a specific goal. For example, a workflow receives a customer order and takes whatever actions are necessary to fulfill it. Each workflow run in an AWS resource called a domain, which controls the scope of the workflow. An AWS account can have multiple domains, each of which can contain multiple workflows, but workflows in different domains cannot interact.

Understand the different Amazon SWF actors.
Amazon SWF interacts with a number of different types of programmatic actors. Actors can be activity workers, workflow starters, or deciders.

Understand Amazon SNS basics.
Amazon SNS is a push notification service that lets you send individual or multiple messages to large numbers of recipients. Amazon SNS consists of two types of clients: publishers and subscribers (sometimes known as producers and consumers). Publishers communicate to subscribers asynchronously by sending a message to a topic.

Know the different protocols used with Amazon SNS.
You can use the following protocols with Amazon SNS: HTTP, HTTPS, SNS, email, email-JSON, Amazon SQS, and AWS Lambda.

Exercises

In this section, you create a topic and subscription in Amazon SNS and then publish a message to your topic.

EXERCISE 8.1
Create an Amazon SNS Topic

In this exercise, you will create an Amazon SNS message.

  • Open a browser and navigate to the AWS Management Console. Sign in to your AWS account.
  • Navigate to Mobile Services and then Amazon SNS to load the Amazon SNS dashboard.
  • Create a new topic, and use MyTopic for both the topic name and the display name.
  • Note that an Amazon Resource Name (ARN) is specified immediately.
    Congratulations! You have created you first topic.
     
    EXERCISE 8.2
    Create a Subscription to Your Topic

In this exercise, you will create a subscription to the newly created topic using your email address. Then you confirm your email address.

  • In the Amazon SNS dashboard of the AWS Management Console, navigate to Topics.
  • Select the ARN that you just created. Create a Subscription with the protocol of Email, and enter your email address.
  • Create a Subscription.
  • The service sends a confirmation email to your email address. Before this subscription can go live, you need to click on the link in the email that AWS sent you to confirm your email address. Check your email, and confirm your address.
    Congratulations! You have now confirmed your email address and created a subscription to a topic.

EXERCISE 8.3
Publish to a Topic
In this exercise, you Will publish a message to your newly created topic.

  • In the Amazon SNS dashboard of the AWS Management Console, navigate to topics.
  • Navigate to the ARN link for your newly created topic.
  • Update the subject with My Test Message, leave the message format to set to Raw, and use a Time to Live (TTL) field to 300.
  • Publish the message.
  • You should receive an email from your topic name with the subject that you specified. If you do not receive this email, check you junk folder.
    Congratulations! In this exercise, you created a new topic, added a new subscription, and then published a message to your new topic. Note the different formats in which you can publish message, including HTTP and AWS Lambda. Delete you newly created topic and subscriptions after you are finished.
     
    EXERCISE 8.4
    Create Queue
  • In the AWS Management Console, navigate to Application Services and then to Amazon SQS to load the Amazon SQS dashboard.
  • Create a new queue with input as the queue name, 60 seconds for the default visibility, and 5 minutes for the message retention period. Leave the remaining default values for this exercise.
  • Create the queue.
    Congratulations! In this exercise, you created a new queue. You will publish to this queue in the following exercise.

EXERCISE 8.5
Subscribe Queue to SNS Topic

  • In the AWS Management Console, navigate to Application Services and then to Amazon SQS to load the Amazon SQS dashboard.
  • Subscribe your queue to your Amazon SNS topic.
  • Now return to the Amazon SNS dashboard (in the AWS Management Console under Mobile Services).
  • Publish to your new topic, and use the defaults.
  • Return to the Amazon SQS dashboard (in the AWS Management Console under Application Services).
  • You win notice there is “1 Message Available” in the input queue. Check the input box to the left of the input queue name.
  • Start polling for messages. You should see the Amazon SNS message in your queue.
  • Click the More Details link to see the details of the message.
  • Review your message, and click Close.
  • Delete your message.
    Congratulation! In this exercise, you subscribed Your input queue to an Amazon SNS topic and viewed your message in your Amazon SQS queue in addition to receiving the message in subscribed email.
     
    Review Questions
    Which of the following is not a supported Amazon Simple Notification Service (Amazon SNS) protocol?
  • HTTPS
  • AWS Lambda
  • Email-JSON
  • Amazon DynamoDB

When you create a new Amazon Simple Notification Service (Amazon SNS) topic, which of the following is created automatically?

  • An Amazon Resource Name (ARN)
  • A subscriber
  • An Amazon Simple Queue Service (Amazon SQS) queue to deliver your Amazon SNS topic
  • A message

Which of the following are features ‘of Amazon Simple Notification Service (Amazon SNS)? (Choose 3 answers)

  • Publishers
  • Readers
  • Subscribers
  • Topic

What is the default time for an Amazon Simple Queue Service (Amazon SQS) Visibility timeout?

  • 30 seconds
  • 60 seconds
  • 1 hour
  • 12 hours

What is the longest time available for an Amazon Simple Queue Service (Amazon SQS) visibility timeout?

  • 30 seconds
  • 60 seconds
  • 1 hour
  • 12 hours

Which of the following options are valid properties of an Amazon Simple Queue Service (Amazon SQS) message? (Choose 2 answers)

  • Destination
  • Message ID
  • Type
  • Body

You are a solutions architect who is working for a mobile application company that wants to use Amazon Simple Workflow Service (Amazon SWF) for their new takeout ordering application. They will have multiple workflows that will need to interact. What should you advise them to do in structuring the design of their Amazon SWF environment?

  • Use multiple domains, each containing a single workflow, and design the workflows to interact across the different domains.
  • Use a single domain containing multiple workflows. In this manner, the workflows will be able to interact.
  • Use a single domain with a single workflow and collapse all activities to within this Single workflow.
  • Workflows cannot interact with each other; they would be better off using Amazon Simple Queue Service (Amazon SQS) and Amazon Simple Notification Service (Amazon SNS) for their application.

In Amazon Simple Workflow Service (Amazon SWF), which of the following are actors? (Choose 3 answers)

  • Activity workers
  • Workflow starters
  • Deciders
  • Activity tasks

You are designing a new application, and you need to ensure that the components of your application are not tightly coupled. You are trying to decide between the different AWS Cloud services to use to achieve this goal. Your requirements are that messages between your application components may not be delivered more than once, tasks must be completed in either a synchronous or asynchronous fashion, and there must be some form of application logic that decides what do when tasks have been completed. What application service should you use?

  • Amazon Simple Queue Service (Amazon SQS)
  • Amazon Simple Workflow Service (Amazon SWF)
  • Amazon Simple Storage Service (Amazon S3)
  • Amazon Simple Email Service (Amazon SES)

How does Amazon Simple Queue Service (Amazon SQS) deliver messages?

  • Last In, First Out (LIFO)
  • First In, First Out (FIFO)
  • Sequentially
  • Amazon SQS doesn’t guarantee delivery of your messages in any particular order.
     
    Of the following options, what is an efficient way to fanout a single Amazon Simple Notification Service (Amazon SNS) message to multiple Amazon Simple Queue Service (Amazon SQS) queues?
  • Create an Amazon SNS topic using Amazon SNS. Then create and subscribe multiple Amazon SQS queues sent to the Amazon SNS topic.
  • Create one Amazon SQS queue that subscribes to multiple Amazon SNS topics.
  • Amazon SNS allows exactly one subscriber to each topic, so fanout is not possible.
  • Create an Amazon SNS topic using Amazon SNS. Create an application that subscribes to that topic and duplicates the message. Send copies to multiple Amazon SQS queues.

Your application polls an Amazon Simple Queue Service (Amazon SQS) queue frequently and returns immediately, often with empty ReceiveMessageResponses. What is one thing that can be done to reduce Amazon SQS costs?

  • Pricing on Amazon SQS does not include a cost for service requests; therefore, there is no concern.
  • Increase the timeout value for short polling to wait for messages longer before returning a response.
  • Change the message visibility value to a higher number.
  • Use long polling by supplying a WaitTimeSeconds of greater than 0 seconds when calling ReceiveMessage.

What is the longest time available for an Amazon Simple Queue Service (Amazon SQS) long polling timeout?

  • 10 seconds
  • 20 seconds
  • 30 seconds
  • 1 hour

What is the longest configurable message retention period for Amazon Simple Queue Service (Amazon SQS)?

  • 30 minutes
  • 4 days
  • 30 seconds
  • 14 days

What is the default message retention period for Amazon Simple Queue Service (Amazon SQS)?

  • 30 minutes
  • 4 days
  • 30 seconds
  • 14 days

Amazon Simple Notification Service (Amazon SNS) is a push notification service that lets you send individual or multiple messages to large numbers of recipients. What types of you send clients are supported?

  • Java and JavaScript clients that support publisher and subscriber types
  • Producers and consumers supported by C and C++ clients
  • Mobile and AMQP support for publisher and subscriber client types
  • Publisher and subscriber client types

In Amazon Simple Workflow Service (Amazon SWF), a decider is responsible for what?

  • Executing each step of the work
  • Defining work coordination logic by specifying work sequencing, timing, and failure conditions
  • Executing your workflow
  • Registering activities and workflow with Amazon SWF

Can an Amazon Simple Notification Service (Amazon SNS) topic be recreated with a previously used topic name?

  • Yes. The topic name should typically be available after 24 hours after the previous topic with the same name has been deleted.
  • Yes. The topic name should typically be available after 1—3 hours after the previous topic with the same name has been deleted.
  • Yes. The topic name should typically be available after 30-60 seconds after the previous topic with the same name has been deleted.
  • At this time, this feature is not supported.

What should you do in order to grant a different AWS account permission to your Amazon Simple Queue Service (Amazon SQS) queue?

  • Share credentials to your AWS account and have the other your account’s applications use your account’s credentials to access the Amazon SQS queue.
  • Create a user for that account in AWS Identity and Access Management (IAM) and establish an IAM policy that grants access to the queue.
  • Create an Amazon SQS policy that grants the other account access.
  • Amazon Virtual Private Cloud (Amazon VPC) peering must be used to achieve this.

Can an Amazon Simple Notification Service (Amazon SNS) message be deleted after being published to a topic?

  • Only if a subscriber(s) has/have not read the message yet
  • Only if the Amazon SNS recall message parameter has been set
  • No. After a message has been successfully published to a topic, it cannot be recalled.
  • Yes. However it can be deleted only if the subscribers are Amazon SQS queues.
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