How smart contracts can implement "report once"

This paper explains the main features of and motivation for the “report once” demonstrator1 shown at the 2017 Data For Policy conference. It shows how Ethereum2 smart contracts, based on the semantics and algorithmic representations defined in ACTUS3 can implement “digital doppelgängers” of financial contracts.   
 
The implementation makes use of a private4 Ethereum blockchain, with smart contracts written in Solidity.5 The limitations of using ACTUS in a semi real-time scenario are explored, as well as how to overcome these limitations.  
 
The major innovation, visualized by the demonstrator, is that compliance reports can be generated in semi realtime, using the information present in the “digital doppelgängers”, residing in the blockchain.  
 
The demonstrator supports various use cases, illustrated through the narration of stories. In these stories, Alice, Bob and Eve are contracting parties, Romeo acts as regulator, and the narrator tells the stories.  The stories cover trading a Bond, trading an Interest Rate Swap (IRS), the defaulting of a party (i.e. a payment stop), and various types of regulatory reports.