Asynchronous Processing with the Messaging Pattern

In the last chapter, we discussed the Fan-out Pattern, which we can implement using different strategies. At the end of that section, we reviewed an implementation of the Fan-out Pattern, which used AWS's Simple Queuing Service (SQS) as a destination for an event trigger. Queuing systems such as SQS provide a level of safety and security because they're intended to be a mostly durable persistent store where data lives until some process has the chance to pull it out, perform some work, and delete the item. If a downstream worker processes a crash entirely and processing stops for some time, queues merely back up, drastically reducing the risk of data loss. If a worker process runs into some unrecoverable problem in the middle of processing, queue items will typically be left on the queue to be retried...