Execute immediately when you perform the Lambda Invoke API call.

▪ Wait for the function to process the function and return back to response.

▪ API Gateway + Lambda + DynamoDB

▪ Invocation-type flag should be “RequestResponse”

▪ Responsible for inspecting the response

and determining if there was an error

and decide to retry the invocation

▪ Example of synchronous invocation using the AWS CLI:

aws lambda invoke —function-name MyLambdaFunction —invocation-type RequestResponse —payload '{ "key": "value" }’

▪ Triggered AWS services of synchronous invocation; ELB (Application Load Balancer), Cognito,

Lex, Alexa, API Gateway, CloudFront, Kinesis Data Firehose

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