Blockchain platforms, such as Ethereum, don't rely on a central authority to allow a set of actors to maintain a ledger of transactions. Additionally it is possible to deploy scripts, called smart contracts, which get executed whenever certain transactions occur. This talk, initially hold on the 2th Oktober 2018 @camunda in Berlin, explores if smart contracts could be used as basic building blocks for executing collaborative business processes between mutually untrusting parties.

1. Smart Contracts Nothing but
Decentralised Workflows?
Why compiling BPMN into Solidity could make sense

2. My Background
● 2013 First Analysis of Bitcoins ability to act as currency.
● 2017 Master Thesis ~ “A blockchain based version control system for
documents“
● 2018 Initial thoughts on linking “smart contracts” to Business Process
Automation
● 2018+ Active research in this area

3. This talk is about
● Cutting through the jungle of blockchain projects.
● Exploring the core of “smart contracts”
● Show which value BPMN could add to the
Blockchain Ecosystem

4. This talk it not
● A detailed discussion about how blockchain works.
● About Bitcoin
● Including any crypto investment advice
● Even close to cover the topic completely

5. The Ethereum Blockchain

6. What does a blockchain do again?
No new technology at all - but a smart combination of multiple existing once!
● Blockchain is a technology that combines a data structure (or database) and a
peer-to-peer network.
● Each block in the blockchain includes a group of transactions
● The creation of a new block requires solving a computationally hard cryptographic puzzle.
● Some nodes in the network are responsible for mining blocks.
● With each cryptographic puzzle a hash value is created that links blocks in the database.
● Any attempt to change a transaction in a block would require the computational costs of
recreating all subsequence blocks.

7. How is the Ethereum Blockchain difference?
● Ethereum, also allow to deploy scripts, called smart contracts, that are executed
whenever certain transactions occur.
● Smart contracts are executed over an Ethereum Virtual Machine (EVM)

8. Ethereum Technology Stack
https://www.slideshare.net/SherminVoshmgir/ethereum-61549934

9. What does all this have to do with BPMN?

10. https://www.ethereum.org/
Value Proposition of
Ethereum

11. https://www.cbinsights.com/research/what-is-
ethereum/
Value Proposition of
Ethereum

12. https://newalchemy.io/
Value Proposition of
Smart Contracts

13. Most Famous Implementation:
“The Decentralized Autonomous Organization”
Goal
“Codify the rules and decision making apparatus of an
organization, eliminating the need for documents and people in
governing, creating a structure with decentralized control.”
https://medium.com/@pullnews/understanding-the-dao-hack-fo
r-journalists-2312dd43e993

14. The DAO Launch
● Launched on 30th April, 2016.
● Largest crowdfunding in history, raised over
$150m from more than 11,000 enthusiastic
members.
● 50 investment opportunity to vote for by
members.

15. The DAO Hack
● $70M were drained on June 18, 2016, by making
the smart contract return Funds multiple times
before it update its own balance.
● One of the Flaw:
○ The DAO coders had also failed to consider
the possibility of a recursive call.
https://coincodex.com/article/50/the-dao-hack-what-happened-and-what-followed/

16. Relevant Etherium Properties
● Turing-complete
● Own programming language “Solidity”
○ syntax resembles the one of JavaScript.
○ Similar classes in Java-like object-oriented style
○ strongly-typed language
● Immutability of deployed code & complete computations
● No central authority
○ Cannot fail, be stopped or censored

17. ● Lack of transparency
● Vulnerable to Errors (only write
operation!)
Smart Contract Properties

18. Bernd Rücker’s Thoughts
https://blog.bernd-ruecker.com/how-blockchain-can-drastically-simplify-business-processes-cc0828918b85
“A thought experiment we did was to
generate Ethereum smart contract code
out of a BPMN model.
“This would...mak(e) BPMN a pretty
interesting tool in the blockchain
technology landscape.”

19. Caterpillar Project
“Caterpillar accepts as input a process model specified in BPMN and generates a set of smart
contracts that captures the underlying behavior.”

20. Background
● Title
○ CATERPILLAR: A Business Process Execution Engine on the Ethereum Blockchain
● Published
○ 10 Jul 2018
● By
○ Orlenys López-Pintado, Luciano García-Bañuelos, Marlon Dumas, Ingo Weber, Alex
Ponomarev
● Universities
○ Institute of Computer Science, University of Tartu, Estonia
○ CSIRO, Sydney, Australia
○ School of Computer Science & Engineering, UNSW Australia, Sydney, Australia

21. What does it do
● BPMN-to-Solidity compiler covering the full
spectrum of BPMN
● The full state of the process instance is
recorded on the blockchain
● External entity can query the state of a given
process instance, i.e. the set of activities that
are currently active (executing) for that
particular instance.
https://arxiv.org/pdf/1808.03517.pdf

22. Demo

23. Check it out!
https://github.com/orlenyslp/Caterpillar

24. Technical Limitations
● Slow & Expensive to use
● Tradeoff between efficiency and the ability to run
inter-linked business processes entirely on the blockchain.
● Collaborative BPMN processes executed outside of the
realm of any involved party.

25. This talk was about
● Cutting through the jungle of blockchain
projects.
● Exploring the core of “smart contracts”
● Show which value BPMN could add to
the Blockchain Ecosystem