The document summarizes a presentation on blockchain technology and the HumanityCoins project. It includes an agenda that discusses introducing blockchain, the structure of chaincode, and implementing the HumanityCoins chaincode. Testing the chaincode involved following test-driven development principles. Issues with the changing codebase and cloud environment were addressed. Future work may involve integrating rewards and connecting with additional applications and networks. The presenter thanks their mentors for their guidance throughout the summer internship working on this project.
1. Open Mainframe Project
Summer internship
Blockchain technology
Laszlo Szoboszlai
Linux Foundation
Date of presentation (02/11/2016)
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2. • Introduction to Blockchain technology and the project
• Structure of a chaincode
• Personal approach to writing HumanityCoins chaincode
• Demo (if everything goes well)
Agenda
3. Short introduction to blockchain
• Distributed ledger technology
• Stores chaincode, not a currency like bitcoin
• High security through distributed ledger (all nodes need
to be altered at the same time)
• Ideal for batch operation (consensus takes time)
• Hyperledger fabric is the Linux Foundation’s
implementation of blockchain
4. Introduction to the project
• Humanity Coins
• The idea comes from IBM fellow Donna Dillenberger
• System to encourage people to do good things
• You can give (thank) points to someone who done a
good deed to you
5. Introduction to the project
(technical details)
• Three levels of thanks: small(1 point), medium (5 pts)
and large (10 points)
• An optional message can be added to the thank
• Points and messages are stored on the ledger
• Front end (mobile) application can access the ledger
through rest API (under development)
• Tweeting auditor to ensure fair use of the system
6. My work through the project
• Setting up development environment (Golang, docker etc…)
• Testing different settings of networks by increasing security level
• Creating a shell script to start up four validating peers with security,
encryption and consensus enabled, similar to IBM’s High Security
Business Network
• Writing the chaincode, the application written on top of hyperledger
infrastructure
• Github code:
• HumanityCoins chaincode encapsulated in a hyperledger peer as a
docker container:
7. Structure of a Chaincode
• Every chaincode has to implement 3 functions (Init, Invoke, Query)
• Can have more functions on top of the above 3
• The functions can do anything but traditionally
– Init : initialises data on the ledger
– Invoke : used to modify data on the ledger and
– Query : is for reading data from the ledger
• Coded in Go programming language (now Java is supported as
well, and more coming)
• Data stored as key – value pairs (keys tend to be strings, values on
the ledger are byte arrays)
8. Implementation of chaincode
(unusual functions)
• Let’s call it addThanks instead of Invoke
• Three types of Query: getUser, getKeys and getRandomUser
instead of a single query
9. Implementation of the
chaincode
(data structures)
• Structs are converted to a
JSON object before written to the ledger
• Each user has a thanklist stored where the
name of the thanker, the type of the thank
and a short message is stored
• In order to make getRandomUser() easier
the user names are stored in a separate
struct as well (KeyList)
10. Implementation of the
chaincode
(init function)
• Init is used to initialise the users with their starting points
• Usernames and initial points are passed through args
• Requires even number of parameters
• KeylistObj is filled simultaneously
11. Implementation of chaincode
(init function cont’d)
• Entity struct is filled from variables and empty thanklist is created
• Entity struct to JSON object -> ledger
• KeyListObj to JSON object -> ledger (PutState function)
• Initialisation ready
12. Testing
• Tried to follow TDD principles
• After initial skeleton chaincode I created a test script in bash ( first
time all tests failed)
• Tweaked all the functions to pass all the tests
• Extended the chaincode with the extra functions (getKeys(),
getRandomUser() ) but first I created the test scenarios that needed
to be passed
• Finally everything was green
13. Issues & solutions
• Rapidly changing codebase -> stick to v 0.5
• Issues with LinuxONE on Marist cloud -> got a box from Vicom
Infinity (and another one later)
• Changing project -> writing own chaincode instead of using IBM
demo code
• Connect to IBM HSBN -> set up a HSBN simulation on my box
14. Future work
• Rewards part of chaincode and app (ie Coffee shop
gives free cup of coffee to people over 1000 points)
• Integration with smart meters
• Port to IBM Bluemix
• Connect with Zos connect
15. Things I have learnt trough the
summer
• How to write a chaincode
• How Hyperledger fabric blockchain works
• Go programming language
• Docker
• Advanced bash scripting
• TDD, agile methodologies
• How to communicate with stakeholders
16. Few bigThanks
(the 10 points one )
go to:
• Volodymyr Paprotski (my mentor, IBM)
• Herbert Daly (co-mentor, University of Bedfordshire)
• Leonard Santalucia (co-mentor, Vicom Infinity)
• Yongkook Kim (co-mentor, Vicom Infinity)
• Development team on slack
• people from Marist College
18. Session feedback
• Please submit your feedback at
http://conferences.gse.org.uk/2016/feedback/nn
• Session is nn
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Notas del editor
A distributed ledger is a consensus of replicated, shared, and synchronized digital data geographically spread across multiple sites, countries, and/or institutions.
Unexpected non financial “thank” random acts of kindness
New currency (no cost to you )
On public blockchain so governments can see it
