An introductory presentation on the main concepts of blockchain technologies, with a special focus on the smart contracts. The slides supported the talk held at the Cyber 4.0 Seminar on Cyber 4.0 Seminar on “Blockchain and Smart Contracts: Concepts and applications” on 2021-03-03, virtually hosted by the Sapienza University of Rome for the Cyber 4.0 Competence Centre.

1. Blockchain and
smart contracts:
infrastructure and
platforms
Claudio Di Ciccio | http://diciccio.net | claudio.diciccio@uniroma1.it
Sapienza, University of Rome, Italy
Cyber 4.0 Seminar, 2021, March the 3rd

2. Claudio Di Ciccio
Assistant professor
Ph.D. in Computer Science and Engineering
Main researchinterests:
process mining,
blockchains,
declarative process modelling,
service-orientedarchitectures
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3. My experience so far
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Latina, Italy (B.Sc) Rome, Italy (M.Sc, Ph.D) Vienna, Austria (Post-doc, Assistant Prof .) Rome, Italy (Assistant Prof .)
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4. Half empty or half full?
http://aeon.co/ideas/which-is-more-fundamental-processes-or-things
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5. Processes are into dynamics
Thanks Dr. Mieke Jans for offering her hand
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6. Blockchain as an
infrastructure
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7. Transaction
• Transfer of (crypto)assets (Ether, Bitcoin, Litecoin, EOS, …)
from account A to account B
Externally Owned
Account (EOA)
Externally Owned
Account (EOA)
Digital signature
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8. Ledger
• Ordered collection of transactions
• The order matters!
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9. Block
• Blocks group and collate transactions
• The order matters!
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10. Hashing the previous block for immutability
• Blocks refer back to direct predecessors
• The order matters!
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11. The Blockchain remembers
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12. Ledgers
• A ledger is a collection of transactions.
 Throughout history, on paper; recently, stored digitally
• Shortcomings of centralised ledgers:
 They may be lost or destroyed:
a user must trust that the owner is properly backing up
the system
 Transactions may not be valid:
a user must trust that the owner is validating each
received transaction
 The transaction list may not be complete:
a user must trust that the owner is including all valid
transactions that have been received
 The transaction data may have been altered:
a user must trust that the owner is not altering past
transactions
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13. Decentralisation for persistence
Centralisation Decentralisation
Distributing the ledger makes for permanence
BUT
entails no notion of unique distributed clock
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14. Distributed nature
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15. Distributed nature
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16. Distributed nature
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17. Mining for a blockchain
Proof of Work (PoW): obtain the right to publish the
next block by solving a computationally intensive
puzzle
Checking that a solution is valid is easy
Solving the puzzle is difficult: an incentive is needed
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18. Ledgers are distributed and
maintained by a network
https://ehtstats.net https://ehternodes.org
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19. Crypto-fuel needed!
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20. From peer-to-peer electronic cash system
to programmable distributed environment
“A universal platform with internal programming language, so that
everyone could write any app”
[V. Buterin]
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21. Smart Contracts are
codified autonomous agents
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22. Smart Contracts are
pieces of code
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23. Smart Contracts are
pieces of code
• Smart Contracts in Ethereum
 live in the Ethereum environment
 execute a function when called
 have direct control over their own balance
and key/value storage
 have their behaviour fully specified by their
code
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24. The polygraph machine
Where are Smart Contracts
executed?
First on the mining nodes.
Then, potentially, on every node!
Only absolutely needed
instructions should be put in code!
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25. A programmable distributed environment
Gas price (execution costs)
Input (and output) encoded data.
Smart Contract
Account
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New
Smart Contract
Account
New address
Smart contract code to be deployed
Invoking a smart
contract function
Deploying a new
smart contract

26. Distributed nature
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27. Smart Contracts are
pieces of code (not for free)
Wood 2014
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28. Tokens are not cryptofuel
Nothing specific of blockchains, after all!
1:5
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29. Your brand new token in 5 minutes or less
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30. Tokens
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31. Tokens
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32. The Blockchain and the Internet
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33. Web 1.0
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Back end Front end
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34. Web 2.0
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35. Web 3.0
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36. Blockchain as a process execution infrastructure
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37. Division of labour → Automation
Draw out
wire
Straight wire Cut wire Grind wire
Put head on
pin
Put pin
in paper
Whiten pin
Point wire
Make head
Icons © freepik.com
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38. Systems like to report on their job (logging)
• [2019-02-18T12:30:00-02:00] 0xACDC0801 executes Draw Out
Wire on Item 0xAA01
• [2019-02-18T12:30:10-02:00] 0xACDC0802 executes Straight
Wire on Item 0xAA01
• [2019-02-18T12:30:20-02:00] 0xACDC0803 executes Cut Wire on
Item 0xAA01
• [2019-02-18T12:30:30-02:00] 0xACDC0801 executes Draw Out
Wire on Item 0xAA02
• [2019-02-18T12:30:40-02:00] 0xACDC0802 executes Straight
Wire on Item 0xAA02
• [2019-02-18T12:30:50-02:00] 0xACDC0804 executes Point Wire
on Item 0xAA01
• [2019-02-18T12:31:00-02:00] 0xACDC0801 executes Draw Out
Wire on Item 0xAA03
• …
Icons © freepik.com
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39. Smart contracts can execute processes
Bulk Buyer BB Trigger
Smart
Contract
Manufact-
urer
Mf. Trigger
API call:
Order goods
Blockchain
Transaction
(BCTX)
Smart Contract effect
Check
conformance
API call
Middleman
Mm. Trigger
API call:
Place order
Execute
internal logic
BCTX
Smart Contract effect
Check
conformance
API call
Weber et al.: Untrusted business process monitoring and execution using blockchain. In: Proc. of BPM. Springer, 2016.
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40. Executing inter-organisational processes on the
Blockchain: A model-driven approach
D.C, Cecconi, Dumas et al. Blockchain support for collaborative business processes. Informatik Spektrum pp. 1–9 (May 2019)
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41. Executing inter-organisational processes on the
Blockchain: A model-driven approach
Caterpillar Lorikeet
D.C, Cecconi, Dumas et al. Blockchain support for collaborative business processes. Informatik Spektrum pp. 1–9 (May 2019)
López-Pintado,García-Bañuelos,Dumas,Weber.Caterpillar: A blockchain-based business process management system.In: BPM Demos.CEUR.ws,2017.
Tran, Lu, Weber. Lorikeet: A Model-DrivenEngineering Tool for Blockchain-Based Business Process Executionand Asset.In: BPM Demos.CEUR.ws,2018.
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42. Rationale
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D.C. et al. Blockchain-Based Traceability of Inter-organisational Business Processes. In: BMSD. Springer, 2018.
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43. Rationale
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D.C. et al. Blockchain-Based Traceability of Inter-organisational Business Processes. In: BMSD. Springer, 2018.
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44. Coming next:
Smart contracts ×
supply chain (demo)
Claudio Di Ciccio | http://diciccio.net | claudio.diciccio@uniroma1.it
Sapienza, University of Rome, Italy
Blockchain Tech course 2020-21 at Sapienza:
https://sites.google.com/uniroma1.it/cfa-msc-blockchaintech/

45. Blockchain and
smart contracts:
infrastructure and
platforms
Claudio Di Ciccio | http://diciccio.net | claudio.diciccio@uniroma1.it
Sapienza, University of Rome, Italy
Blockchain Tech course 2020-21 at Sapienza:
https://sites.google.com/uniroma1.it/cfa-msc-blockchaintech/

46. How about the real world?
Oracles: From on-chain to off-chain and vice versa
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47. Etherisc
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48. Flight delay insurance:
the FlightDelayPayout contract
Payout in case of
signalled problems
with the flight
Contact with the
off-chain world
Source: https://www.flickr.com/photos/michaelduxbury/5824469025
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49. The problem
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DB

50. The Oracle
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Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World. BPM (Blockchain and RPA Forum) 2020: 35-51
DB
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51. The Oracle
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Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World. BPM (Blockchain and RPA Forum) 2020: 35-51
DB
ISO/TC 307, ISO/TR 2345: “[A] DLT Oracle [is a] service that updates a distributed
ledger using data from outside the distributed ledger system”. (2019)
Previous literature: oracles as off-chain information providers.
We see oracles as a bridge
between the on-chain and off-chain worlds.
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52. Oracle patterns: Overview
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Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World. BPM (Blockchain and RPA Forum) 2020: 35-51