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Mule Events

A Mule event contains the core information processed by the runtime. It travels through components inside your Mule app following the configured application logic.

Note that the Mule event is immutable, so every change to an instance of a Mule event results in the creation of a new instance.

A Mule event is composed of these objects:

  • A Mule Message contains a message payload and its associated attributes.

  • Variables are Mule event metadata that you use in your flow.

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A Message source, such as the Scheduler, HTTP Listener, or On New or Updated File component, triggers the generation of a Mule event and dispatches that event to the flow.

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  1. A trigger reaches the event source.

  2. The event source produces a Mule event.

  3. The Mule event travels sequentially through the components of a flow.

  4. Each component interacts in a pre-defined manner with the Mule event.

In some cases when an issue occurs in a Message source, the component does not produce a Mule event. For example, invalid or incorrect paths in an HTTP listener configuration prevents the creation of a Mule event. Connectors log such issues in ERROR, WARN, or INFO messages.