Poll-Based Event Sources for AWS Lambda Functions

Answer: B, C, D.

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AWS Lambda is a compute service provided by AWS that allows developers to run code in response to events and automatically manages the computing resources required by that code. One of the key benefits of Lambda is its ability to integrate with other AWS services to automatically trigger the execution of Lambda functions based on events happening in those services.

There are three main types of event sources for AWS Lambda: push-based, pull-based, and stream-based. Push-based event sources, such as AWS S3 and AWS CloudFormation, send events directly to a Lambda function when an action occurs. Stream-based event sources, such as Amazon Kinesis Data Streams and AWS DynamoDB Streams, send records to a Lambda function as they are generated. Pull-based event sources, on the other hand, require the Lambda function to poll the event source periodically to check for new events.

Now, let's look at the options provided in the question and identify the three poll-based event sources for AWS Lambda:

A. AWS SNS: AWS Simple Notification Service (SNS) is a push-based event source for AWS Lambda, so it is not a poll-based event source.

B. AWS Kinesis: Amazon Kinesis Data Streams is a stream-based event source for AWS Lambda, so it is not a poll-based event source.

C. AWS SQS: AWS Simple Queue Service (SQS) is a pull-based event source for AWS Lambda. A Lambda function can be configured to poll an SQS queue for new messages, and then execute the function with the contents of the message.

D. AWS DynamoDB: AWS DynamoDB is a stream-based event source for AWS Lambda, so it is not a poll-based event source.

E. AWS CodePipeline: AWS CodePipeline is a push-based event source for AWS Lambda, so it is not a poll-based event source.

Therefore, the three poll-based event sources for AWS Lambda are AWS SQS, AWS EventBridge, and AWS Systems Manager.