Event Processing Pattern

Question 1

Event Processing Patterns

Answer 1

Dead Letter Queue
Fan out pattern
S3 event notifications

Question 2

What is Dead Letter Queue

Answer 2

Dead letter queue is where the all the exveptional scenarios are sent to Queue/sns for further analysis
There are three AWS services which uses DLQ:
SNS:
Messages published to a topic that fail to deliver are sent to an SQS queue; held for further analysis or reprocessing.

SQS:
Messages sent to SQS that exceed the queue’s maxReceiveCount are sent to DLQ(another SQS queue)

Lambda
Results from failed asynchronous invocations; will retry twice and send to either an SQS queue or SNS topic

Moving in to DLQ might infer that there might be bugs in the application which needs our attention

Question 3

what is Fanout Pattern

Answer 3

Fanout Pattern is a pattern where if a message is requied by multiple systems instead of sneding messages to all the systems.. send it to SNS topic and let the message be published to all the subscribers with an identical copy of the message.

Question 4

s3 event notifications

Answer 4

S3 events notifications triggered by:
Obbjects Created
Objects Deleted
Objects Restored in glacier
RRS Objects lost
Objects Replication

S3 event notifications are consumed by:
SNS
SQS
Lambda