The presentation at DevFest Tokyo 2017 / @__timakin__ An introduction of blockchain and why go is nice to implement blockchain. Additionally described about the blockchain projects that are based on Go.

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