Which type of flow in Mule starts with a message source?

A flow in Mule that starts with a message source is known as a regular flow. Regular flows are designed to respond to incoming events or data, which means they initiate execution based on messages received from these sources. This could include HTTP requests, file system changes, or messages in queues, among others.

Regular flows are fundamental components of Mule applications, allowing for the orchestration of various tasks and transformations in response to incoming data. On the other hand, sub flows are typically called from other flows and do not start with their own message sources, while private flows are similar but are not accessible from outside their parent flow. Asynchronous flows revolve around non-blocking behavior but still rely on a message source for initiation, which doesn't define their essence as a distinct flow type. The key characteristic of regular flows is that they begin with a message source, making them essential for building responsive applications in MuleSoft.