AWS Links

 Aurora










 https://docs.aws.amazon.com/lambda/latest/dg/invocation-eventsourcemapping.html






Reserved concurrency for function put upper limit on number of requests(use to limit overloading downstream system), can use autoscaling for provisioned concurrency


In asynchronous operation, the caller places the event on an internal queue, which is then processed by the Lambda function. The internal queue between the caller and the function ensures that messages are stored durably. The Lambda service scales up the concurrency of the processing function as this internal queue grows. If an error occurs in the Lambda function, the retry behavior is determined by the Lambda service. Although Lambda functions can run for up to 15 minutes, synchronous callers may have shorter timeouts. For example, API Gateway has a 29-second integration timeout,

The problem while doing asynchronous invocation is that it was really hard to see if the event had succeeded or failed. And if it did, then how can we retrieve it? Initially, for asynchronous invocations events, DLQ (Dead Letter Queue) was the only way possible, but it has certain limitations as it has limited targets like SQS and SNS. Secondly, it only allows for sending failure events to the target and does not allow for sending success events. To overcome these issues, AWS came up with a feature called Lambda Destinations.

Lambda Destinations is a feature that helps to send the results of asynchronous invocation to multiple targets. Unlike DLQ, in Lambda Destinations, it is possible to define destinations for processing of successful and failed events. As mentioned, this feature supports multiple targets like SQS, SNS, Lambda, and Eventbridge Bus.













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