Which statement describes the behavior of flow variables across transport boundaries?

Which statement describes the behavior of flow variables across transport boundaries?

• A. Flow variables persist across all transports
• B. flow variables persist across some but not all transport barriers (VM yes, HTTP no)
• C. Flow variables persist through all flows unless the message crosses a transport boundary
• D. within a single flow only

Answer: (C)

Flow variables are tied to the current flow invocation. They carry data along processing inside the same flow (and even across internal flow calls), but when the message crosses a transport boundary, a new Mule event is created and flow variables are reset. So they persist through internal flow transitions, but not when the message moves across transports (for example, VM to HTTP). This is why the statement that best fits is that flow variables persist through all flows unless the message crosses a transport boundary.

Flow variables are tied to the current flow invocation. They carry data along processing inside the same flow (and even across internal flow calls), but when the message crosses a transport boundary, a new Mule event is created and flow variables are reset. So they persist through internal flow transitions, but not when the message moves across transports (for example, VM to HTTP). This is why the statement that best fits is that flow variables persist through all flows unless the message crosses a transport boundary.