Application Integration Flashcards
What is Amazon SQS?
A fully managed message queuing service that enables you to decouple and scale microservices, distributed systems, and serverless applications.
What are the two types of SQS queues?
Standard Queues: Offer high throughput, best-effort ordering, and at-least-once delivery.
FIFO Queues: Strict message ordering and exactly-once processing.
What is the maximum message size for SQS?
256 KB (can be larger with SQS Extended Client)
What is a Dead Letter Queue (DLQ)?
An SQS queue that stores messages that failed to process after a number of attempts. Useful for debugging and troubleshooting.
What are message attributes in SQS?
Metadata that can be attached to SQS messages for filtering and routing.
Explain ‘at-least-once delivery’ in SQS.
SQS guarantees that messages will be delivered at least once, but duplicates are possible in rare cases.
What is the purpose of the ‘Delay Seconds’ attribute in SQS?
Allows you to delay the delivery of a message to a queue for a specified number of seconds.
How can you achieve ‘exactly-once delivery’ with SQS?
Use FIFO queues, which provide inherent message deduplication and ordering.
How can you scale SQS consumers?
By adding more consumers to poll the queue, SQS automatically handles the distribution of messages.
What are some ways to monitor SQS queues?
Use Amazon CloudWatch metrics (e.g., NumberOfMessagesSent, NumberOfMessagesReceived, ApproximateNumberOfMessagesVisible)
What is Amazon SNS?
A fully managed pub/sub messaging service that enables you to fan out messages to a large number of subscribers, including SQS queues, Lambda functions, and email addresses.
What are some benefits of using SNS?
High scalability
Message durability
Integration with various AWS services.
What types of endpoints can subscribe to an SNS topic?
SQS queues, Lambda functions, HTTP/S endpoints, email addresses, SMS numbers, mobile push notifications.
What is the purpose of message filtering in SNS?
Allows subscribers to receive only messages that match specific criteria defined in a filter policy.
How does SNS handle message delivery retries?
SNS retries failed deliveries to HTTP/S endpoints with exponential backoff.
What are the different message delivery protocols supported by SNS?
HTTP/S, email, SMS, SQS, Lambda, and mobile push notifications.
What is the ‘fan-out’ pattern with SNS and SQS?
A design where one SNS topic sends the same message to multiple SQS queues for parallel processing.
What is AWS Step Functions?
A serverless orchestration service that makes it easy to coordinate multiple AWS services into serverless workflows. Provides a visual console to build and manage workflows.
What are some common use cases for Step Functions?
Microservice orchestration
Data processing pipelines
Machine learning workflows.
What are the different types of states in Step Functions?
Task, Choice, Wait, Parallel, Map, Pass, Succeed, Fail.
How can you handle errors in Step Functions workflows?
Use ‘Retry’ and ‘Catch’ fields within state definitions to handle specific error types and implement retry logic.
What is the purpose of the ‘InputPath’ and ‘OutputPath’ fields in Step Functions state definitions?
Control which parts of the state input are passed to the task and which parts of the task output are passed to the next state.
What is Amazon EventBridge?
A serverless event bus that makes it easy to connect applications with data from a variety of sources. Allows for real-time responses to events.
What is the EventBridge Schema Registry?
Stores event schemas, allowing you to validate and govern the structure of events flowing through your event buses.
What are the different ways to trigger an EventBridge rule?
Schedule (cron expressions), Event Pattern (matching events from AWS services or other sources).
What are event buses in EventBridge?
Targets that receive events. You can have default event buses, custom event buses, and partner event buses.
How can you archive and replay events in EventBridge?
Use the event archive feature to store events for a specified duration or indefinitely, and then replay them for auditing or debugging.
What are some examples of events that can be sent to EventBridge?
S3 object created events, EC2 instance state changes, CloudWatch alarms, custom application events.
What is the difference between SNS and EventBridge?
SNS is focused on pub/sub messaging, while EventBridge is a broader event bus that can route events between AWS services, SaaS apps, and your own applications.
What is Amazon Managed Workflows for Apache Airflow (MWAA)?
A managed service that makes it easy to run Apache Airflow on AWS. Airflow is a platform for programmatically authoring, scheduling, and monitoring workflows.
What is a DAG in Apache Airflow?
A Directed Acyclic Graph that represents a workflow, where nodes represent tasks and edges represent dependencies between tasks.
How are workflows defined in Apache Airflow?
Using Python code to create Directed Acyclic Graphs (DAGs).
What are some key features of MWAA?
Managed service - no need to install/maintain Airflow
Scalable
Integrates with many AWS services.
How does MWAA handle scaling of Airflow workers?
MWAA automatically scales the number of worker containers based on the workload and configured limits.
How can you access the Airflow web server in MWAA?
Through a private or public endpoint, managed by AWS IAM.
What is the purpose of ‘Visibility Timeout’ in SQS?
Prevents other consumers from processing a message while it’s being handled by another consumer. The message is returned to the queue if not deleted within the timeout.
