What is Scatter-Gather and how does it differ from Parallel For Each?

Scatter-Gather: Sends the same message to multiple routes (different processors/connectors) simultaneously and collects all results. Each route can perform different operations. The result is a composite object (Map) keyed by route index with each route's output. All routes receive the same input event. If any route fails, Scatter-Gather throws an error by default (all-or-nothing). Use case: call multiple downstream systems in parallel and aggregate responses (e.g., query inventory + pricing + CRM simultaneously and combine). Parallel For Each: Processes a collection of items, applying the same logic to each item in parallel. All iterations use the same processing logic. Key distinction: Scatter-Gather is for different operations on the same data; Parallel For Each is for the same operation on different data items.