in BPM we will send an async message to SAP backend system, we need to know if the message is successfully process or not, if not, we need to get the detail info which is returned in the acknowledgement message.
As you know in PI monitor, you can open the acknowledgement message and you can see the error texts that are sent by the SAP backend system to PI in the acknowledgement message. However seems like there is no standard way in PI BPM to get the error texts inside the acknowledgement. In the send step you can only specify that application ACK is required, if negative ACK comes in, an exception is raised and you can handle the exception in the exception branch. However there is nowhere to capture the acknowledgement message to get the detail error texts.
Anyone has good idea to get the error texts from the application acknowledgment message inside BPM/