A process model specifies the steps that must happen and the sequence in which they must happen based on the results of each step. Some steps invoke services to create outbound business documents or process inbound business documents. Other steps wait for business documents to be received from trading partners.
If you receive a business document from a trading partner, but either you did not expect a business document (that is, the conversation is not waiting for a business document) or the business document that you received is not the business document that you expected (that is, you receive the wrong business document), the
Process Engine handles the received business document as an out‐of‐sequence or unhandled business document. The arrival of an unhandled business document causes the
Process Engine to place the conversation in an error state by sending the conversation to the
Error step. The
Error step invokes the
pub.estd.chem:error service in the WmChem package. This service generates a general exception and sends the exception to the trading partner who sent the unexpected business document.
An example might be when the process model specifies the business documents to send and receive in a certain order, but the order in which the conversation actually sends and receives the business documents becomes scrambled during the communications over the Internet. This could cause a business document to arrive before it is scheduled, according to the specified order.