[farazbabar]

And in the absence of correctly designed idempotent behaviors across the processing pipeline, it becomes unbelievably complex to handle all the corner cases correctly. The problem with marketing folks parroting and promoting the exactly once semantics is that any weak link in the processing chain compromises the correctness of entire system and what is worse is that the implications of subtle errors may not become evident for years to come (history is rife with legal cases and negative consequences of getting it wrong when it comes to folks' money).

In critical sectors like banking, finance and payments, designing systems in well understood and boring manner is absolutely critical while hoping for the best based on shiny brochures and marketechture is a sure recipe for disaster.