Default error handling

When an exception is detected within a node, the message and the exception information are propagated to the Failure terminal on the node. If the node does not have a Failure terminal, or it is not connected, the broker throws an exception and returns control to the closest upstream node that can process it. The default behavior is that the message is returned to the input node.

The actions taken by the input node are protocol-dependent; if your message flow starts with an MQInput, its error handling is different from the error handling provided by a FileInput node.

The actions also depend on whether you have configured the message flow to be transactional. Some nodes support transactions; others are non-transactional. If the message is not being processed in a transaction, the message is discarded by the input node. If the flow is transactional, the message is returned to its source; for example, it is restored on the WebSphere® MQ queue.

If basic error processing is not sufficient, and you want to take specific action in response to certain error conditions and situations, you can enhance your message flows to provide your own error handling. For example, you can add in a sequence of nodes to deal with one or more errors that you might expect to occur in your flow. You can also configure your flow to handle unexpected errors (exceptions). For more details about the actions that you can take, see Handling errors in message flows.