This recipe suggests various approaches to implement the fan-in/fan-out architectural patterns in AWS. The fan-in and fan-out patterns may be used together, or even separately. They may also be used in a different order, fan-in followed by fan-out or fan-out followed by fan-in. The first scenario occurs when multiple producers send data to a single scalable service (fan-in) and consumers consume data in parallel (fan-out) and process it. The latter scenario, of fan-out followed by a fan-in, can be used in situations where we want to process a task in parallel (fan-out) through different services, and then combine the individual outputs into a single output (fan-in) for generating the final result. We may even combine these scenarios into a fan-in, fan-out, fan-in combo.