placing TN routing service in appropriate Try/Catch sequence will ensure the flow goes into the catch block whenever exception is thrown by the routing service. How to handle error in the catch block is upto you.
TN processing rule is never ran or is never executed. Processing rules specify how you want Trading Networks to process documents. For example, you might want Trading Networks to send an alert e-mail message to a contact, and then deliver the document to the receiver that is identified in the document.
For each document that Trading Networks is to process, it performs a processing rule
lookup to determine which processing rule to use for a specific document. After Trading Networks finds the appropriate processing rule for a document, it performs
the pre-processing and processing actions. It at all there no processing rule defined which matches the criteria, Trading Networks select default processing rule. So processing rule as such will never go into an error.
Although there might be cases in which processing rule is not able to execute the processing service. e.g the flow service is renamed or deleted. I am not sure how this kind of exception be handled in TN.
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