The document outlines the concept of blockchain and decentralized applications, detailing the technical components such as nodes, proofs of work and stake, and the Ethereum blockchain ecosystem. It includes examples of code for smart contracts in Solidity and instructions for setting up private Ethereum networks and utilizing BigchainDB alongside IPFS for decentralized storage. Additionally, it references various resources and installation guides for Ethereum and related technologies.

1. Concept of
BlockChain
&
Decentralized
Application
timakin / @__timakin__
YAP(achimon)C::Asia Hachioji 2016 mid in Shinagawa

3. • github: timakin
• twitter: @__timakin__
• DeNA -> Translimit
• Go / Ruby / Node
• Blog
medium: https://medium.com/@timakin
timekin.log: http://tech-savvy.hatenablog.com/

5. •
•
•
•
•

7. •
•
•
•

9. P2P

11. P2P

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

13. Inside of blockchain
• JSON
JSON
•
nonce
• parent hash
hash

14. 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',
}

15. Chain management
• P2P
Node json
• Node

16. A
B
C
fork

17. 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

19. •
• PoW
10
•
•
• PoS
•
•
• Node
•

23. DApp Stack

24. Decentralized Application
P2P Node
Permanent web

25. Decentralized Application
Processing
File Storage Database

26. Decentralized Application
Processing
File Storage Database
Processing
File Storage Database

27. Euthareum
•
•
ether

28. Euthareum Client
• Geth (go-euthareum)
Node

29. Install
https://github.com/ethereum/go-ethereum
OS
# install euthareum
$ brew tap ethereum/ethereum
$ brew install ethereum
# install go, gmp
$ brew install gmp go
# install geth
$ git clone https://github.com/ethereum/go-ethereum
$ cd go-ethereum
$ make geth

30. Build private network
$ mkdir /home/test_u/eth_private_net
{
"nonce": "0x0000000000000042",
"timestamp": "0x0",
"parentHash":
"0x0000000000000000000000000000000000000000000000000000000000000000",
"extraData": "0x0",
"gasLimit": "0x8000000",
"difficulty": "0x4000",
"mixhash":
"0x0000000000000000000000000000000000000000000000000000000000000000",
"coinbase": "0x3333333333333333333333333333333333333333",
"alloc": {}
}
Genesis

31. Connect to private network
$ geth --networkid "10" --nodiscover --datadir "/home/test_u/
eth_private_net" --genesis "/home/test_u/eth_private_net/
myGenesis.json" console 2>> /home/test_u/eth_private_net/
geth_err.log
# private 10 id
# peer
# console

32. Contract Code
# Solidity
$ sudo add-apt-repository ppa:ethereum/ethereum
$ sudo apt-get update
$ sudo apt-get install solc
$ brew install cpp-ethereum
$ brew linkapps cpp-ethereum
$ solc —-version
$ which solc
# solc geth
$ admin.setSolc(“which solc path")
$ eth.getCompilers()
•
• Ethereum Virtual Machine
Euthareum
• Solidity
• IDE: https://github.com/ethereum/browser-solidity

33. Contract Code
# Solidity
contract SingleNumRegister {
uint storedData;
function set(uint x) {
storedData = x;
}
function get() constant returns (uint retVal) {
return storedData;
}
}
Solidity JavaScript

34. Contract Code
#
$ var source = "contract SingleNumRegister { uint storedData;
function set(uint x) { storedData = x; } function get() constant
returns (uint retVal) { return storedData; }}"
$ var sourceCompiled = eth.compile.solidity(source)
#
$ var contractAbiDefinition =
sourceCompiled.SingleNumRegister.info.abiDefinition
$ var sourceCompiledContract = eth.contract(contractAbiDefinition)
$ var contract = sourceCompiledContract.new({from:eth.accounts[0],
data: sourceCompiled.SingleNumRegister.code})
Node

35. Contract Code
$ contract
{
address: '0x8ea277dfe4195daf7b8c101d79da35d1eb4c4aeb',
transactionHash:
'0xeb76caefdfe5a9aa10b11743d317cf15f881d3b2e52ba3251dcf8e0718ed5b33'
,
allEvents: function (),
get: function (),
set: function ()
}
#
$ contractAbiDefinition

36. Contract Code
#
$ var cnt = eth.contract([{ constant: false, inputs: [{ name: 'x',
type: 'uint256' } ], name: 'set', outputs: [ ], type: 'function' },
{ constant: true, inputs: [ ], name: 'get', outputs: [{ name:
'retVal', type: 'uint256' } ], type:
'function' } ]).at(‘0x8ea277dfe4195daf7b8c101d79da35d1eb4c4aeb');
#
$ cnt.set.sendTransaction(3,{from:eth.accounts[0]})
‘0x979c4e413a647673632d74a6c8b7f5b25a3260f3fefa4abea2dc265d61215939'
#
$ cnt.get()

37. Run the app on EVM
# RPC geth
$ geth --networkid "10" --nodiscover --datadir "/home/test_u/
eth_private_net" --genesis "/home/test_u/eth_private_net/myGenesis.json"
--mine --unlock 0xa7653f153f9ead98dc3be08abfc5314f596f97c6 --rpc --rpcaddr
"192.168.5.6" --rpcport "8545" --rpccorsdomain "*" console 2>> /home/
test_u/eth_private_net/geth_err.log
# meteor project
$ cd ~/eth-test #
$ meteor create simple-app # Meteor
$ meteor add twbs:bootstrap
$ meteor add ethereum:web3
$ meteor add ethereum:accounts
$ meteor add ethereum:blocks
EVM

38. Run the app on EVM
# geth
$ vim client/lib/init.js
```
//Web3
web3 = new Web3();
//RPC
if(!web3.currentProvider)
web3.setProvider(new web3.providers.HttpProvider("http://localhost:
8545"));
// EthAccounts
EthAccounts.init();
//EthBlocks
EthBlocks.init();
```

39. Run the app on EVM
$ vim client/main.html
```
<head>
<title>Simple Ether Wallet</title>
</head>
<body>
<template name="nodeStatusComponent">
<div class="panel panel-default">
<div class="panel-heading">
<h4>Node Status</h4>
</div>
<table class="table">
<tbody>
<tr>
<th scope="row">Node</th>
<td>{{currentProvider}}</td>
</tr>
<tr>
<th scope="row">Is Mining?</th>
<td>{{isMining}}</td>
</tr>
<tr>
<th scope="row">Hashrate</th>
<td>{{currentHashrate}}</td>
</tr>
<tr>
<th scope="row">Peer Count</th>
<td>{{currentPeerCount}}</td>
</tr>
</tbody>
</table>
</div>
</template>
```

40. Run the app on EVM
#
$ vim client/main.html
```
<head>
<title>Simple Ether Wallet</title>
</head>
<body>
<template name="nodeStatusComponent">
<div class="panel panel-default">
<div class="panel-heading">
<h4>Node Status</h4>
</div>
<table class="table">
<tbody>
<tr>
<th scope="row">Node</th>
<td>{{currentProvider}}</td>
</tr>
<tr>
<th scope="row">Is Mining?</th>
<td>{{isMining}}</td>
</tr>
<tr>
<th scope="row">Hashrate</th>
<td>{{currentHashrate}}</td>
</tr>
<tr>
<th scope="row">Peer Count</th>
<td>{{currentPeerCount}}</td>
</tr>
</tbody>
</table>
</div>
</template>
```

41. Run the app on EVM
#
$ vim client/main.js
```
// nodeStatusComponent
Template.nodeStatusComponent.helpers({
//
currentProvider: function(){
return web3.currentProvider.host;
},
//
// true false
isMining: function(){
return web3.eth.mining;
},
//
currentHashrate: function(){
return web3.eth.hashrate;
},
//
currentPeerCount: function(){
return web3.net.peerCount;
}
});
```
meteor

42. Euthareum
•
• Euthareum

43. BigChainDB
•
•
• key-value
JSON
• python

44. BigChainDB
RethinkDB
BigChainDB
https://speakerdeck.com/vrde/bigchaindb-how-we-built-a-blockchain-database-
on-top-of-rethinkdb

45. Install, Configuration
# rethinkdb http://rethinkdb.com/docs/install/
# bigchainDB
$ sudo pip install bigchaindb
$ vim instance1.conf
```
server-tag=original
directory=/data
bind=all
direct-io
# Replace node?_hostname with actual node hostnames below, e.g.
rdb.examples.com
join=node0_hostname:29015
join=node1_hostname:29015
join=node2_hostname:29015
# continue until there's a join= line for each node in the
federation
```

46. Run the BigChainDB server
# rethinkdb bigchaindb server
$ rethinkdb --config-file path/to/instance1.conf
$ bigchaindb init
$ bigchaindb set-shards 1
$ bigchaindb set-replicas 1
$ bigchaindb start

47. Create a Digital Asset
from bigchaindb import crypto
#
testuser1_priv, testuser1_pub = crypto.generate_key_pair()
#
digital_asset_payload = {'msg': 'Hello BigchainDB!'}
#
tx = b.create_transaction(b.me, testuser1_pub, None, 'CREATE',
payload=digital_asset_payload)
#
tx_signed = b.sign_transaction(tx, b.me_private)
#
b.write_transaction(tx_signed)
#
tx_retrieved = b.get_transaction(tx_signed['id'])
tx_retrieved

48. BigChainDB
•
• key-value RethinkDB

49. IPFS
•
• gateway REST API
curl
• P2P

50. Install
https://ipfs.io/docs/install/
go
#
$ ipfs init
$ ipfs daemon
# peer
$ ipfs swarm peers
# ipfs image
$ ipfs cat /ipfs/QmW2WQi7j6c7UgJTarActp7tDNikE4B2qXtFCfLPdsgaTQ/cat.jpg
>cat.jpg
$ open cat.jpg
# localhost webui
$ open http://localhost:5001/webui

51. WEBUI

52. 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

53. 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

54. ex) gx-go
https://github.com/whyrusleeping/gx-go
ipfs version
go package manager

55. ex) ipfs-pics
https://ipfs.pics/
ipfs
script

56. IPFS
•
• gateway REST API curl
• gateway
(https://ipfs.io/ipfs/$hash)
•

57. DApp
•
• DB Storage
CDN
BigChainDB
Peer Node IPFS
Peer Node
Processing
File Storage Database
tr tr tr
bb b
bb b bb b

59. •
• P2P
CDN
• Node
Client-Server
• or <

60. •
http://www.meti.go.jp/press/2016/04/20160428003/
20160428003-2.pdf
•
http://www.slideshare.net/ks91020/ss-58535780
• 5
http://www.slideshare.net/cookle/5-58379474

61. • Ethereum-WhitePaper-JP
https://github.com/kurihei/Ethereum-WhitePaper-JP/blob/master/%5BJapanese%5D-White-
Paper.md
• Ethereum Specification
https://github.com/ethereum/go-ethereum/wiki/Ethereum-Specification
• Gitbook Ethereum
https://www.gitbook.com/book/a-mitani/mastering-ethereum/details
• BigchainDB: how we built a blockchain database on top of RethinkDB
https://speakerdeck.com/vrde/bigchaindb-how-we-built-a-blockchain-database-on-top-of-rethinkdb
• White Paper: BigchainDB: A Scalable Blockchain Database(DRAFT)
https://www.bigchaindb.com/whitepaper/bigchaindb-whitepaper.pdf
• White Paper: IPFS - Content Addressed, Versioned, P2P File System (DRAFT 3)
https://ipfs.io/ipfs/QmR7GSQM93Cx5eAg6a6yRzNde1FQv7uL6X1o4k7zrJa3LX/ipfs.draft3.pdf

62. • OSS
Go Go
• Docs White Paper
pdf
•
• Euthareum
Github
Github