Application Services Flashcards by Jim Owen

What is Kinesis Analytics?

Service which allows you to run SQL queries against data inside Kinesis Streams or Firehose, and then use the query to store the data in S3, Redshift, or an Elasticsearch Cluster

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What is Kinesis

It used to consume huge amounts of data. A platform in AWS to send your streaming data to. Kinesis makes it easy to load and analyze streaming data, and allows you to make custom applications.

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How long can SQS messages be kept in the queue?

From 1 minute to 14 days, with a default of 4 days

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If an SQS queue is producing messages faster than resources can consume them, what can you do?

Create an autoscaling group triggered by the number of messages in the queue to automatically scale up or down

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What is the file format of SNS messages?

JSON

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How are SWF Domains stored?

They are JSON files

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How long do shards remain in Kinesis Streams?

24 hours (default) up to 7 days

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How many transactions per second can be processed by a standard SQS queue?

Nearly unlimited

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What is SQS Long Polling?

It is a way to retrieve messages from a queue that might be empty. With regular polling, SQS returns an immediate response, but with long polling, SQS doesn’t return a response until a message arrivesor the long polling time out

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Is SQS pull or push based?

SQS is pull based, meaning the consuming resources are pulling messages from the queue

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How many transactions per second can be processed by a fifo SQS queue?

300 per second

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What do you do if API Gateway gives an error regarding the Same Origin Policy?

CORS must be enabled on the API Gateway

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How do you prevent service attacks to API Gateway?

You can enable throttling in API Gateway

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Is SNS pull or push based

SNS is push based, meaning it “pushes” notifications to consuming services such as email, text, CloudWatch, etc

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What are the two types of SQS queues?

1`. Standard queue (default) - A message is guaranteed to be delivered, but there might occasionally be a duplicate, and it has best-effort ordering, so messages may not be processed in the order they were sent
2. Fifo queues - Guarantees messages will be processed in the same order they were sent and exactly once

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True or false: API Gateway requests can be logged in CloudWatch

True

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What is SNS?

Simple Notification Service - Used to deliver notifications, such as CloudWatch alerts or emails, to subscribers based on conditions in AWS

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What is Elastic Transcoder?

A media transcoder in the cloud. It allows you to convert media files from an original source format to different formats that work on other devices

What is the Same Origin Policy?

A common web application concept. Under this policy, a web browser permits scripts contained in a first web page to access data in a second web page, but only if both pages have the same origin

Explain API Gateway caching

Responses from requests to API Gateway can be cached for a specified TTL time. If the same request comes in within that time, API Gateway returns the cached response, preventing another ping to the endpoint

What are some indicators that a process should be using SWF instead of SQS?

Is there any human interaction?

Are there multiple interrelated steps to a single process?

What is a SWF Domain?

A set of tasks that make up a single workflow. You register SWF domains

Explain Kinesis Streams

Sources, such as mobile devices, computers, EC2 instances, IoT devices, send data into Kinesis Streams. Data is stored in Shards. You then have EC2 instances that are data consumers, that do processing on the shards, then they send the data to DynamoDB, S3, EMR, Redshift, etc.

What are the different types of SWF actors?

Workflow Starters - An application that initiates a workflow
Workers - perform workflow tasks
Deciders - control the flow of activity in a workflow

What is the maximum retention period for an SWF workflow?

1 year

What are some differences between SQS and SWF?

SQS is messae-oriented, SWF is task-oriented SWF guarantees tasks will br processed exactly once. SWF monitors the progress of tasks and execution state. With SQS you have to keep track of this yourself

How do components retrieve SQS messages?

Using the SQS API

What is API Gateway?

It's a portal for collecting HTTP requests and forwarding them to some internal process such as a Lambda function or EC2 Instance

What is SWF?

Simple Workflow Service. A service which lets you create a workflow of discrete steps that will be processed in sequence and that can span multiple resources.

How large can SQS messages be, and what can they contain?

they can be any text format and up to 256 Kb

What is SQS Visibility Time Out?

The amount of time a message in invisible in the queue after it was picked up. If the message is processed, it is deleted. If not, it becomes visible in the queue again. The Visibility Time Out determines how long SQS will leave a message in the invisible state

What is an SNS Topic?

A collection of subscribers which can have multiple endpoint types. SNS can send a message to a topic, then all the subscribers to the topic will receive that message in whatever format needed

What is the SQS Visibility Time Out maximum?

12 hours

What are the three core Kinesis services?

Kinesis Streams Kinesis Firehose Kinesis Analytics

True of false: SQS guarantees that every message will be processed at least once

True. With Fifo queues it guarantees it will be processed exactly once

What is SQS?

Simple Query Service. Gives access to a message queue that can be used to queue messages that one component in the application generates to be consumed by another component

What are shards?

Individual piece of data received by Kinesis Streams and stored in EC2 instances for processing

What is streaming data?

Data that is generated continuously by thousands of data sources, in many very small packets. Examples includes social media, online gaming, Uber, IoT sensor data

What is Kinesis Firehose?

Service which consumes streaming data, then automatically processes it using Lambda and sends it off to S3

How is SNS charged?

Pay-as-you-go, depending on delivery method. Email is more expensive than text, which is more expensive than HTTP etc.

What is the difference between Kinesis Streams and Kinesis Firehose?

Streams collects data in shards, which are then consumed by EC2 resources for processing. Firehose automates the processing of streaming data

True or false: API Gateway scales automatically

True

What are some possible SNS endpoints?

``` HTTP/S Email, Email-JSON SQS Text messages (SMS) Lambda functions ```