Development with AWS Services

1. What is AWS Lambda and when should it be used?

• AWS Lambda is a serverless computing platform that allows you to run code without having to provision or manage servers. It’s a good choice for running event-driven applications or when you need to perform automatic tasks in response to specific events.

2. What is DynamoDB and how does it differ from a traditional relational database?

• DynamoDB is a NoSQL database service provided by AWS. It differs from a traditional relational database in that it’s a document-based database that allows for more flexible and scalable data modeling. Unlike a relational database, DynamoDB does not use SQL and does not require a fixed schema.

3. What is SQS and how does it work?

• SQS (Simple Queue Service) is a managed message queue service provided by AWS. It works by allowing you to send, store, and receive messages between distributed systems and microservices. The messages are stored in a queue and can be processed in order by multiple consumers.

4. What is SNS and what are some use cases for it?

• SNS (Simple Notification Service) is a publish-subscribe messaging service provided by AWS. It can be used to send notifications and messages to a large number of subscribers, such as email addresses, SMS messages, or HTTP/HTTPS endpoints. Some common use cases include sending updates to customers, sending notifications to microservices, and triggering Lambda functions in response to specific events.

5. What are the benefits of using AWS Lambda over traditional server deployment methods?

• Some benefits of using AWS Lambda include:
  • Cost savings: You only pay for the compute time you consume and do not have to pay for unused capacity or idle servers.
  • Scalability: AWS Lambda automatically scales your applications in response to incoming request traffic.
  • Flexibility: AWS Lambda allows you to run code written in a variety of programming languages and can be triggered by events from other AWS services.
  • No server management: You do not have to worry about managing and patching servers, as AWS handles all of the infrastructure for you.

6. How does DynamoDB handle data consistency?

• DynamoDB provides two types of consistency: eventual consistency and strong consistency. By default, DynamoDB uses eventual consistency, which means that after a write operation, it may take some time for the changes to be reflected in all storage locations. You can opt for strong consistency, which provides immediate read access to updated data, at the cost of slightly higher latency.

7. What are the differences between SQS and SNS?

• SQS and SNS are both messaging services provided by AWS, but they have different use cases:
  • SQS is used for transmitting messages between distributed systems and microservices in a decoupled manner. It provides a message queue that allows for asynchronous communication.
  • SNS is used for broadcast communication and sending notifications to multiple subscribers. It acts as a centralized message broker that can distribute messages to a large number of subscribers, including email, SMS, and HTTPS endpoints.

8. How can you trigger a Lambda function from an SQS message?

• You can trigger a Lambda function from an SQS message by setting up an SQS trigger in the AWS Management Console. When a new message is added to the queue, it will trigger your Lambda function, passing the contents of the message as an input to the function. This allows you to process messages from SQS in a serverless and scalable manner using AWS Lambda.

9. Can you use DynamoDB as a source for a Lambda function trigger?

• Yes, you can use DynamoDB as a source for a Lambda function trigger. When a new item is added or an existing item is updated in a DynamoDB table, a Lambda function can be triggered to perform an action in response to the change in the table. This is useful for performing real-time processing and analysis of data stored in DynamoDB.

10. How does SNS handle delivering messages to a large number of subscribers?

• SNS uses a publish-subscribe model to deliver messages to subscribers. When a message is published to an SNS topic, the message is delivered to all subscribers of that topic, including email addresses, SMS numbers, HTTPS endpoints, and other SNS topics. SNS handles the distribution of messages to subscribers, ensuring that each subscriber receives a copy of the message.

11. Can you use SQS to send messages between AWS accounts?

• Yes, you can use SQS to send messages between AWS accounts. You can grant access to an SQS queue in one AWS account to users in another AWS account. The recipient account users can then receive messages from the queue and perform actions in response to the messages. This allows you to share data and exchange messages between AWS accounts in a secure and scalable manner.

12. How can you secure an SNS topic and its subscribers?

• You can secure an SNS topic and its subscribers by using AWS Identity and Access Management (IAM) policies. IAM policies can be used to control who has access to an SNS topic and what actions they can perform on the topic. Additionally, you can use encryption to secure the data transmitted over an SNS topic. SNS supports the use of SSL/TLS to encrypt data in transit, and SNS messages can be encrypted using server-side encryption with Amazon S3 or Amazon KMS.

13. What is the role of IAM in securing Lambda functions and DynamoDB tables?

• IAM plays a crucial role in securing Lambda functions and DynamoDB tables. With IAM, you can control who has access to your AWS resources and what actions they can perform. For example, you can use IAM policies to grant or deny access to a specific Lambda function or DynamoDB table based on the identity of the caller. This can help prevent unauthorized access to your resources and ensure that only authorized users can perform actions on your resources.

14. How can you monitor the performance of a Lambda function?

• You can monitor the performance of a Lambda function using CloudWatch Logs, CloudWatch Metrics, and CloudWatch Alarms. CloudWatch Logs provides detailed logs of the function execution, including any errors or exceptions. CloudWatch Metrics provides performance metrics for your Lambda function, such as the number of invocations, the duration of each execution, and the amount of memory used. CloudWatch Alarms can be set up to trigger alerts based on specific performance thresholds, allowing you to take proactive action to address any performance issues.

15. Can you use DynamoDB streams to trigger a Lambda function?

• Yes, you can use DynamoDB streams to trigger a Lambda function. When a new item is added or an existing item is updated in a DynamoDB table, the change can be written to a DynamoDB stream. The stream can then be used to trigger a Lambda function, allowing you to perform real-time processing and analysis of data stored in DynamoDB. This is useful for integrating DynamoDB data into other AWS services and building event-driven applications.

16. What is the maximum size of a message that can be sent to an SQS queue?

• The maximum size of a message that can be sent to an SQS queue is 256 KB. This size limit allows you to store large amounts of data in an SQS message, but also ensures that messages are small enough to be processed quickly and efficiently by consumers. If you need to send larger amounts of data, you can store the data in S3 or another service and send a reference to the data in the SQS message.

17. How does SNS handle message durability and delivery guarantees?

• SNS provides durability and delivery guarantees for messages sent to SNS topics. SNS stores messages in multiple AWS regions to ensure high durability and availability. SNS also supports at-least-once delivery, meaning that messages are delivered to subscribers at least once, and in the order in which they were published. If a message cannot be delivered to a subscriber, SNS will continue to retry delivery until the message is successfully delivered or the message expires.

18. What is the maximum size of a record in a DynamoDB stream?

• The maximum size of a record in a DynamoDB stream is 1 MB. This size limit ensures that records in the stream are small enough to be processed quickly and efficiently by consumers. If you need to store larger amounts of data in a DynamoDB table, you can store the data in S3 or another service and store a reference to the data in the DynamoDB table.

19. Can you use SNS to send messages to multiple AWS services at the same time?

• Yes, you can use SNS to send messages to multiple AWS services at the same time. SNS supports the use of multiple protocols for delivering messages to subscribers, including email, SMS, HTTPS, and other SNS topics. This allows you to send messages to a variety of endpoints and integrate SNS into multiple AWS services. For example, you can send a message to both an S3 bucket and a Lambda function at the same time.

20. What is the difference between a DynamoDB table and a DynamoDB stream?

• A DynamoDB table is a NoSQL database that stores data in a key-value format. It is designed to provide fast, predictable performance at scale for read and write operations. A DynamoDB stream is a feature of DynamoDB that captures data changes to a DynamoDB table in real-time. When an item in a DynamoDB table is created, updated, or deleted, the change is written to the associated DynamoDB stream. The stream can then be used to trigger a Lambda function or another AWS service, allowing you to perform real-time processing and analysis of data stored in DynamoDB.

21. Can you use AWS Lambda with other AWS services besides DynamoDB, SQS, and SNS?

• Yes, AWS Lambda integrates with many other AWS services, including but not limited to S3, Kinesis, API Gateway, and CloudWatch. AWS Lambda provides a flexible and scalable platform for building and deploying serverless applications, allowing you to easily integrate and extend your applications using other AWS services as needed.

22. How do you troubleshoot issues with Lambda functions or DynamoDB tables?

• Troubleshooting issues with Lambda functions or DynamoDB tables can involve several steps, including checking CloudWatch Logs and Metrics, reviewing IAM policies and permissions, and verifying the configuration of the function or table. It may also involve testing the function or table in isolation to determine if the issue is specific to that resource or if it is related to another service or component in your application. In some cases, you may need to reach out to AWS Support for further assistance with troubleshooting issues with your resources.

23. What is the difference between a DynamoDB table and a relational database?

• DynamoDB is a NoSQL database, while relational databases use SQL as a query language and store data in tables with rows and columns. DynamoDB stores data as key-value pairs, and allows for fast, predictable performance at scale, while relational databases are optimized for complex querying and transactions.

Relational databases require more setup and management compared to DynamoDB, and can be more challenging to scale horizontally. On the other hand, DynamoDB may not be ideal for applications that require complex joins, transactions, or multi-row updates.

24. What is the purpose of using SQS in a serverless architecture?

• SQS (Simple Queue Service) is used in a serverless architecture to decouple components of an application, allowing them to run asynchronously and independently. When using SQS in a serverless architecture, you can send messages to an SQS queue instead of directly invoking a Lambda function or other AWS service. This can help improve the scalability and resilience of your application, as components can process messages from the queue at their own pace, and can retry processing failed messages as needed.

25. What are some common use cases for SNS?

• SNS (Simple Notification Service) is a fully managed, publish-subscribe messaging service. Some common use cases for SNS include:
• Sending notifications to end-users, such as email or SMS notifications
• Distributing messages to multiple AWS services or endpoints
• Implementing fan-out architectures, where a single message is sent to multiple subscribers
• Processing real-time data streams, such as IoT device data
• Triggering serverless architectures, such as sending messages to a Lambda function to perform some processing or analysis.