What would you like?

Currently, we are always throwing a StepFailedException when a step fails terminally.

This behavior is not ideal because users expect (and this aligns with the other SDK implementations) to be able to catch the original exception that might be thrown from a step. The complexity of this feature is to restore the specific Exception type from the checkpointed ErrorObject data.

Possible Implementation

The ErrorObject (https://docs.aws.amazon.com/lambda/latest/api/API_ErrorObject.html) contains the following fields which are necessary to restore. This is possible by leveraging these fields:

• ErrorData (serialized Exception using SerDes when checkpointing error)
• ErrorType (fully qualified class name of original exception type)

A possible implementation can attempt to:

• Load original ErrorType using Java reflection
  • If class not found, fall back to StepFailedException
• Check if ErrorType is assignable from Throwable
• Deserialize ErrorData into dynamically loaded ErrorType
• Sneaky throw original exception. Needed because Throwable is a checked exception ...
  • https://github.com/aws/aws-durable-execution-sdk-java/blob/main/sdk/src/main/java/com/amazonaws/lambda/durable/util/SneakyThrow.java

Is this a breaking change?

No

Does this require an RFC?

No

Additional Context

No response