DynamoDB Quiz
A company has setup an application in AWS that interacts with DynamoDB. It is required that when an item is modified in a DynamoDB table, an immediate entry is made to the associating application. How can this be accomplished? Choose 2 answers from the choices below.
A. Setup CloudWatch to monitor the DynamoDB table for changes. Then trigger a Lambda function to send the changes to the application.
B. Setup CloudWatch logs to monitor the DynamoDB table for changes. Then trigger AWS SQS to send the changes to the application.
C. Use DynamoDB streams to monitor the changes to the DynamoDB table.
D. Trigger a lambda function to make an associated entry in the application as soon as the DynamoDB streams are modified
C. & D.
When you enable DynamoDB Streams on a table, you can associate the stream ARN with a Lambda function that you write. Immediately after an item in the table is modified, a new record appears in the table’s stream. AWS Lambda polls the stream and invokes your Lambda function synchronously when it detects new stream records. Since our requirement is to have an immediate entry made to an application in case an item in the DynamoDB table is modified, a lambda function is also required.
Let us try to analyze this with an example:
Consider a mobile gaming app that writes to a GamesScores table. Whenever the top score of the GameScores table is updated, a corresponding stream record is written to the table’s stream. This event could then trigger a Lambda function that posts a Congratulatory message on a Social media network handle.
DynamoDB streams can be used to monitor the changes to a DynamoDB table.
AWS Documentation mentions the following:
A DynamoDB stream is an ordered flow of information about changes to items in an Amazon DynamoDB table. When you enable a stream on a table, DynamoDB captures information about every modification to data items in the table.
For more information on DynamoDB streams, please refer to the URL below.
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.html
Note:
DynamoDB is integrated with Lambda so that you can create triggers to events in DynamoDB Streams.
If you enable DynamoDB Streams on a table, you can associate the stream ARN with a Lambda function that you write. Immediately after an item in the table is modified, a new record appears in the table’s stream.
AWS Lambda polls the stream and invokes your Lambda function synchronously when it detects new stream records. Since our requirement states that an item modified in a DynamoDB table causes an immediate entry to an associating application, a lambda function is also required.
For more information on DynamoDB streams Lambda, please refer to the URL below.
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.Lambda.html
