The document provides an overview of blockchain technology using Go programming language, discussing concepts like consensus algorithms, decentralized applications, and various blockchain projects like Ethereum and Hyperledger. It includes technical details such as JSON examples for blocks, proof of work and stake mechanisms, and highlights tools and APIs for interaction with blockchain systems. The document emphasizes community involvement and resources for further exploration in blockchain development.

1. BlockChain on Go
@__timakin__ / DevFest Tokyo 2017

2. •
• Github: timakin / Twitter: @__timakin__
• Gunosy Inc.
• Go / Swift
• community
• golang.tokyo
• roppongi-golunch
• blockchain.tokyo

3. golangtokyo.connpass.com

5. • Blockchain
• Go Blockchain

6. Blockchain
•
• -> JSON
• P2P

7. Chain Flow
hash
target nonce
transactions transactions transactions
blockblock block

8. Example of block
{
difficulty: '137447',
extraData: '0x476574682f76312e302e312f6c696e75782f676f312e342e32',
gasLimit: 3141592,
gasUsed: 0,
hash:
'0x4d3063b91cbaa12bf2de81014c1319febc9f197c93f81b0746afaffaa9496620',
nonce: '0x28fda83cb19ed497',
number: 100,
parentHash:
'0x5885cdec1d1410580eaaf1fb7ef9db245a735822d48e816c73d926b7c9872f15',
size: 536,
timestamp: 1439451765,
totalDifficulty: '13551548',
transactions: [ ],
transactionsRoot:
'0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421',
}

9. Consensus Algorithm
• Proof of Work
• Node 0
Node
• target nonce(hash value)
• Node
• Proof of Stake
•
• ex) SHA256(prevhash + address + timestamp) <= 2^256 * balance (volume of stake) / diff
•
Proof of Stake Velocity

10. Decentralized Application
Processing
File Storage Database
Processing
File Storage Database

11. •
•
•
•
•
• ms
•

12. •
• 2017/10/1 135GB
•

13. •
• Bitcoin Ethereum
•
•
Read/Write

14. •
ms
•
•

15. http://blockchaindemo.io/

16. Go Blockchain
• Go
C++ Python
•
Go

18. Go?
•
•
•
•

19. btcd
• Bitcoin fork
• bitcoin/bitcoin C++
• libbitcoin(C++), BitcoinJ(Java)
•
• JSON-RPC API

20. geth(go-ethereum)
• Go
• Ethereum protocol Go
• Ethereum
• Windows OS
• geth( 7832) cpp-ethereum( 1710),
pythereum( 1487), ethereumj(760)

21. Ethereum
(geth)
P2P
Network
+

22. Mist Wallet

23. https://ethstats.net/

24. HyperLedger
•
• Supported by The Linux Foundation
•
• IBM Intel J.P.Morgan MUFG NEC
etc…

25. HyperLedger
ref: http://gaiax-blockchain.com/hyperledger-project

26. HyperLedger Projects
Fabric
PBFT
*
* http://www.jpx.co.jp/corporate/research-study/working-paper/tvdivq0000008q5y-att/
JPX_working_paper_No15.pdf

27. HyperLedger Fabric Network
ref: https://www.ibm.com/developerworks/jp/cloud/library/j_cl-blockchain-basics-bluemix/

28. PBFT (Practical Byzantine Fault Tolelance)
ref: https://www.ibm.com/developerworks/jp/cloud/library/j_cl-blockchain-basics-bluemix/

29. ChainCode
• Go Java

30. ChainCode

31. World State
• ChainCode R/W KVS JSON
•
ChainCode

32. shim.ChaincodeStubInterface
• chaincode WorldState Ledger
API
• Init, Invoke
• Get/Put/Delete State World State
• shim.Success, shim.Error res payload writer
200, 400,
500

33. HyperLedger Composer
Fabric
Web IDE

34. HyperLedger Composer
Web UI (Fabric)
4
Model:
Access Control: Read/Write
Script: JS
Query:
Model REST API

35. IPFS
• P2P
• Blockchain
•
• ipfs.pics Gyazo Winny

36. Upload assets
#
$ ipfs add test.jpg
added QmaC9pUA3grWJ948u1VWRLG1wPLP8YZe7b3HopBGk4zZyA test.jpg
$ ipfs cat /ipfs/QmaC9pUA3grWJ948u1VWRLG1wPLP8YZe7b3HopBGk4zZyA > butaman.jpg
$ open https://ipfs.io/ipfs/QmaC9pUA3grWJ948u1VWRLG1wPLP8YZe7b3HopBGk4zZyA
#
$ ipfs add -r ~/myproject
# Fuse
$ ipfs mount
$ ls /ipfs/$hash/
#
$ ipfs add -q test.mp4

37. API Client
var ipfs = require('ipfs-client');
var stream =
ipfs.cat('QmTE9Xp76E67vkYeygbKJrsVj8W2LLcyUifuMHMEkyRfUL');
stream.pipe(process.stdout);
ipfs.add(process.stdin, function(err, hash) {
console.log(hash);
});
https://www.npmjs.com/package/ipfs-client
API
Scala Go JavaScript

38. WebUI

39. • Go C++
• API
CLI
• WebUI