1.
Blockchains:
a New Platform for
Semantically Enabled
Transactions
Prof. John Domingue
Director, Knowledge Media Institute,
the Open University, UK
President STI International
http://kmi.open.ac.uk/

2.
Caveat
• Semantic Web
• Semantic Web Services
• Blockchains

3.
MOTIVATION

4.
Our Position in the SW World

5.
WEB IS A PLATFORM
E-commerce
Search Engine Social
Web Portal Travel Online Services
Cloud computing
$28.83
$15.84
$12.29
$10.56
$17.93
$74.98
$107
$9.22
$6.77
$8.59
$6.3
$6.67
$5.37
$4.97
$3.63
$2.99
$3.1
$1.5
$1.40
$0.9
$2.22

6.
Blockchain <-> SWS Relationship (1/2)
• Blockchains
implement trust
• New (transaction)
platform

7.
Blockchain <-> SWS Relationship (2/2)
• Simple concept with complex
implementation
• Re-use important
• Identification important
• No inbuilt search
• Interoperates with plethora of systems
• Implements legal, financial and asset based
transactions

8.
BLOCKCHAINS IMPACT

9.
Blockchain
10
World Economic Forum Survey Projects
Blockchain ‘Tipping Point’ by 2023
Santander: Blockchain Tech Can Save Banks
$20 Billion a Year

10.
IBM: Device Democracy
http://www-935.ibm.com/services/multimedia/GBE03620USEN.pdf

11.
Distributed Autonomous Organisations

12.
BLOCKCHAIN ELEMENTS

13.
What is a blockchain?
A blockchain is a
permissionless
distributed database,
based on the bitcoin
protocol that
maintains a
continuously growing
list of transactional
data records hardened
against tampering and
revision, even by
operators of the data
store's nodes.
The initial and most
widely known
application of the
blockchain technology
is the public ledger of
transactions for bitcoin
and the inspiration of
similar distributed
ledgers known as
altchains.
Each blockchain record
is enforced
cryptographically and
hosted on machines
working as a data store
Source: Wikipedia

14.
Cryptographic Hash Function
https://en.wikipedia.org/wiki/Cryptographic_hash_function

15.
Blockchain is a Linked List (1/2)
A blockchain can be thought of as a linked list of transactions
that is built with hash pointers instead of pointers
Source: Bitcoin and Cryptocurrency Technologies - Arvind Narayanan, Joseph Bonneau, Edward Felten, Andrew Miller, Steven Goldfeder

16.
Blockchain is a Linked List (2/2)
A blockchain actually contains
two different hash structures.
The first is a hash chain of
blocks that links the different
blocks to one another.
The second is internal to each
block and is a Merkle Tree of
transactions within the
blocks.
This allows for efficiently
verifiable proofs that a
transaction was included in a
block.

17.
Ethereum Blockchain Platform

18.
Ethereum is a cryptocurrency platform and Turing-complete programming
framework intended to allow a network of peers to administer their own
stateful user-created smart contracts in the absence of central authority.
It features a blockchain-based virtual machine that securely records and
incentivizes the validation of transactions, i.e. code executions, made
through a cryptocurrency called ether.
Ethereum takes the primary developments used by BitTorrent and Bitcoin,
the peer to peer network and the blockchain, and generalizes them in order
to allow developers to use these technologies for any purpose.
Source: Wikipedia
Ethereum Blockchain Platform

19.
Ethereum Blockchain Platform
Ethereum is a 100% open source software platform to build distributed,
decentralized applications
Ethereum is 100% peer to peer, censorship-proof and corruption-proof.
Ethereum can be used to build anything: Asset issuance, crowdfunding,
domain registration, title registration,predictionmarkets, internet of things,
voting, educational certificate issuing systems, hundreds of applications
Source: Ethereum slides - Stephan Tual and Ethereum in 40 minites by Vitalik Buterin

20.
Ethereum Virtual Machine
Sources: Ethereum Development Tutorial
The Ethereum Virtual Machine can be thought of as a large decentralized computer
containing millions of objects, called "accounts", which have the ability to maintain
an internal database, execute code and talk to each other.
There are 2 types of Accounts:
Externally owned account (EOA):
an account controlled by a private
key that has the ability to send
ether and messages from it.
‘Smart’ Contract: an account
that has its own code, and is
controlled by code.
Any user can trigger an action by sending a transaction from an EOA, setting
Ethereum's wheels in motion.
If the destination of the transaction
is another EOA, then the transaction
may transfer some ether but
otherwise does nothing
However, if the destination is a
‘Smart’ Contract, then the
contract in turn activates, and
automatically runs its code.

21.
What are Ethereum Contracts?
‘Smart’ contracts are computer protocols that facilitate, verify, or enforce the
negotiation or performance of a contract.
‘Smart’ contracts can be partially or fully self-executing, self-enforcing, or both.
Smart contracts in Ethereum have the ability to read/write to their own
internal storage, read the storage of the received message, and send
messages to other contracts, triggering their execution in turn
Sources: Wikipedia and Ethereum Development Tutorial and Ethereum - Introduction to Smart Contracts

22.
Contracts in Ethereum
Maintain a data store
representing
something which is
useful to either other
contracts or to the
outside world
Serve as a sort of
externally owned
account with a more
complicated access
policy
Manage an ongoing
contract or
relationship between
multiple users
Provide functions to
other contracts;
essentially serving as
a software library.
Contracts in Ethereum generally serve 4 purposes:
source: Richard Gendal Brown “A Simple Model for Smart Contracts”
http://gendal.me/2015/02/10/a-simple-model-for-smart-contracts/

23.
DApps
Source: Ethereum - Stephan Tual
A Đapp is a decentralised application which serves some
specific purpose to its users, but which has the important
property that the application itself does not depend on
any specific party existing.
Rather than serving as a front-end for selling or providing
a specific party's services, a Đapp is a tool for people and
organizations on different sides of an interaction use to
come together without any centralized intermediary.
A Dapp consists of two parts: a frontend, written in
HTML or QML, and a backend (think of it as the
‘database’ for your frontend).

24.
DBrowsers
It is an end user interface onto
the Ethereum blockchain.
A DBrowser is how users will find
and interact with DApps
‘Mist’ is the name of the
Ethereum DBrowser.

25.
Characteristics of Blockchain DApps
• Shared database
• Multiple writers
• Absence of trust
• Disintermediation
• Transaction interaction
• Set rules
• Validators
• Asset backing
http://www.multichain.com/blog/2015/11/avoiding-pointless-blockchain-project/

26.
HIGHER EDUCATIONAL
EXAMPLE

27.
Demos of movies available at: http://blockchain.open.ac.uk/

28.
Course Contract
Functions:
Storage:
enrol
unenrol
getStudents
studentsPaid[address=0.6, address=0…. ]
students [address, address, address]
Course Administration ViewStudent View
Enrol for 6 ETH!
your Ethereum
address
password to private
key
Signing this transaction will transfer 6
ETH + gas from your account. Estimated
gas cost is 0.02 ETH. Maximum gas cost is
set to 0.05 ETH
Enrol
Student Enrolment Page
Signed
TX
Unenrol Student
Admin Ethereum address
Admin password to private key
Signing this transaction will transfer 6
ETH + gas from course admin account.
Estimated gas cost is 0.02 ETH. Maximum
gas cost is set to 0.05 ETH
Unenrol
Course Admin Page
Signed
TX
Student List
(Listing students is a free transaction)
Course Enrolment Page
Signed
TX
Student
Address
Array
unenrolStudent Account 11
Student Account 23
Student Account 45
Student Account 67
Student Account 89
unenrol
unenrol
unenrol
unenrol
Student Account 67
Course Smart Contract

29.
Jane enrols on an OpenLearn Course

30.
Higher Education Disaggregation

31.
BLOCKCHAINS, SERVICES
AND SEMANTICS

32.
Services -> Smart Contracts
Web service
Operation 1
Operation 2
Operation N
input
input
input
output
output
output
.
..

33.
Services -> Smart Contracts
Web service
Operation 1
Operation 2
Operation N
input
input
input
output
output
output
.
..

34.
Services -> Smart Contracts
Web service
Operation 1
Operation 2
Operation N
.
..

35.
Services -> Smart Contracts
Web service
Operation 1
Operation 2
Operation N
.
..

36.
Services -> Smart Contracts
Web service
Operation 1
Operation 2
Operation N
.
..

37.
Services -> Smart Contracts
Smart Contract
.
..
Transaction 1
Transaction 2
Transaction N

38.
Services -> Smart Contracts
Distributed Autonomous
Organisation
.
..
Transaction 1
Transaction 2
Transaction N

39.
• From
• To
• Value
• Gas
• Gas Price
• Data
• Nonce
web3.eth.sendTransaction(transactionObject[, callback])
Transaction Creation Object

40.
• Block Hash
• Block Number
• Transaction Hash
• Transaction Index
• From
• To
• Cumulative Gas Used
• Gas Used
• Contract Address
• Logs
Transaction Receipt Object
web3.eth.getTransactionReceipt(hashString [, callback])

41.
Minimal Service Model
http://iserve.kmi.open.ac.uk/

42.
http://linked-usdl.org/

43.
http://linked-usdl.org/

44.
BLONDiE Ontology
Matthew English https://github.com/EIS-Bonn/BLONDiE/

45.
Transaction
• From
• To
• Input
– Value
– Data
• Cost
– Currency
– Price
• Block information
• Contract
• Condition
– Financial condition
– Non financial condition
• Effect
– Financial effect
– Non financial effect
• History

46.
Smart Contract
• Transactions
• Condition
– Financial condition
– Non financial condition
• Effect
– Financial effect
– Non financial effect

47.
SUMMARY

48.
Related events
New York, USA, July 6-9 2016

49.
Summary (1/2)
• Blockchain attracting a lot of commercial
and community interest
– Trusted mediator for legal and financial
transactions
– IoT platform
– Disaggregation and disintermediation
– Leaderless Distributed Autonomous
Organisations

50.
Summary (2/2)
• Small subset of the SW/LoD community
focused on processes/services/APIs
• Lot to offer
– Identification
– Search
– Re-use
– Interoperability
– Automation
• Machine <-> machine communication in a
human populated world

51.
Acknowledgements
• KMi@OU Implementation Team
– Michelle Bachler
– Kevin Quick
• Discussants
– Sören Auer, Fraunhofer
– Adi Ben-Ari, Applied Blockchain
– Carla Casilli, Mozilla Open Badges
– Marc Eisenstadt, OU
– Matthew English, Fraunhofer
– Denis Gillet, EPFL
– Hugh Halford-Thompson, Blockchain Tech Ltd
– William Knottenbelt, Imperial College
– Konstantin Kudryavtsev, Ethcore
– Gary McKay, APII
– Rebecca Migirov, Consensys
– Titi Roman, Sintef
– Philipp Schmidt, MIT Media Lab
– Mike Sharples, OU
– Elena Simperl, University of Southampton
– Ashley Taylor, Consensys
– Sergej Zerr, University of Southampton
• Graphics
– Harriett Cornish, OU

52.
blockchain.open.ac.uk