KEMBAR78
Blockchain, Ethereum and Business Applications | PPTX
Blockchain, Ethereum and
Business Applications
@ZimMatthias Matthias Zimmermann
BSI Business Systems Integration AG
Crypto Currencies Market
Bitcoin
First decentralized digital currency
• By «Satoshi Nakamoto»
• White Paper 2008
• Open Source Software 2009
Coffee at Bob‘s
Address
Amount [B]
Name Recipient
1GdK9UzpHBzqzX2A9JFP3Di4weBwqgmoQA
0.015
Bob's Café
Source: «Mastering Bitcoin», Andreas M. Antonopoulos
Addresses corresponds to «Accounts»
Encoded Numbers
 Example: 1GdK9UzpHBzqzX2A9JFP3Di4weBwqgmoQA
 Derived from a private Key
 Private key is 256-Bit random number
Getting, using and loosing Accounts
 Create your account with «Coin, Paper and Pencil»
 No ID required, no showing up at local branch, …
 To send Bitcoins you need your private Key
 You loose your private key  you loose your money
What is a Bitcoin Address?
 Bitcoin network
confirms coffee TX
after ~ 10 min.
 TX Elements
The Coffee Transaction
Bob’s Address Coffee Price
My Address
Link to TX Block
Screenshot: blockchain.info
Change (back to me)
TX Fee
Coffee TX
 Block #277316
includes coffee TX
 Block Elements
Genesis Block
TX Blocks and the Blockchain
419 TX (€495,000)
Link to revious Block#277316
#277315
#2
#1
Screenshot: blockchain.info
Block Hash – do you see the
leading zeros?
From Transactions to Blocks (Mining)
1. New TX are propagatet through Bitcoin peer-to-peer network
2. Bitcoin client verifies new TX and adds it to local «mempool»
3. Client starts to «mine» transactions:
− Assemble TX from mempool to block candidate
− Starts to solve the block candidate’s crypto challenge
− Computes MANY hashes to solve the crypto challenge
− Client solving the challenge first, gets block reward and all TX fees
3. Winning client sends the new block to its peers
4. Arrival of new block triggers the next challenge
From Transactions to Blocks (Mining)
Creation of new Bitcoins
1.5 x 1018
IGraph: blockchain.info
Bitcoin Mining Today
 Mining-pools: Include many ASIC computers (PC way too slow)
 AntMiner: 10,000x faster than PC, burns 10x more electricity
 Energy Costs: # of hashes per KWh is central criteria + cooling(!)
Hashing Power over the Years
The Challenge
 Mining clients build block candidates independently
 Several new blocks might be found at the «same» time
 Clients may receive new blocks that are inconsistent
 The local copy of the blockchain may have forks
The Solution
 The «true» blockchain is defined by the highest cumulative PoW (difficulty)
 By selecting the greatest-difficulty chain, eventual consensus is achieved
 Miner majority vote defines the true chain
 Miners «vote» for the true chain by deciding which block/fork to extend
Distributed Consensus Mechanism
Preventing Forks
? ?
Attacking Bitcoin (any PoW Blockchain)
1. Install more mining capacity than the rest of the world (>= 51%)
2. Censor/suppress unwanted TX
3. Mine a secret branch containing acceptable TX
4. Continue to mine until PoW of secret branch exceeds official branch
5. Broadcast secret branch to Bitcoin network
6. All Bitcoin clients will switch to this new branch
Ok, this is kind of hard – but:
 Miners earn ~1.2bn/year
 HW cost to match Bitcoin mining capacity: ~ $400m (Antminer 9s)
«Unhappy with some TX?»
The 51% Attack
Current Issues
 Increasing TX backlogs
 TX confirmation can take hours (instead of 10’)
 Increasing TX fees
 «War» between Bitcoin Core and Bitcoin Unlimited (Scaling Debate)
 Decreasing market share
Bitcoin Challenges
Bitcoin Market Share
Bitcoin Price
Bitcoin Success
 Completely decentral currency (no need for central banks)
 Open Source (GitHub) and Open Data (complete TX history)
 First successful implementation of any crypto currency
 «Gold Standard» since 2009
 Record price levels
Bitcoin Challenges
 Declining market share
 Scaling debate/war
Bitcoin Recap
Bitcoin Resources
Ethereum
Decentralized Smart Contracts
• 2014 by Vitalik Buterin
• Distributed Turing complete VM
• Open source software 2014
• Is crypto currency too
Ethereum vs Bitcoin
Common Traits
 Local clients/nodes with complete blockchain (open data)
 Concepts of addresses, transactions, mining
 Virtual currency Ether
 Open source
Main Differences
 Specification with different implementations (Bitcoin: single client)
 Turing complete scripting (Bitcoin: very limited scripting)
 Ether is currency unit (1 Ether ~ 87$ 17.05.17)
 Wei is smallest denomination (10-18 Ether)
 TX mining: Proof of Work (PoW)
 Distributed consensus like Bitcoin (true chain == highest cumulative PoW)
Storing Information
 Ethereum clients: Maintain blockchain data + state data
 State data: Account balances + nonces
 Transaction data: Ether transfers
Ethereum as Virtual Currency Platform
Ethereum and App Integration
Ethereum Client
Geth/TestRPC/…
Ethereum
Peer-to-Peer Network
Interface
http://localhost:8545 JSON-RPC
JavaScript
web3 web3j
Java
Ideal Development Setup
 Offline, repeatable, fast
 Java (this is a JUG talk after all)
We can have all this 
 Docker (repeatable, shareable)
 TestRPC (offline + local blockchain /w immediate TX confirmations)
 Web3j (Ethereum Java Library)
Ethereum Hands-on
TestRPC Docker Image
Running TestRPC
container
Open shell in container
Start node.js
TestRPC initial accounts
Get initial balance
New balance
Send 123456789 Weis
 Java implementation of JSON-RPC client API
 A couple of other features
 Android support
web3j: Ethereum and Java
web3j: Creating and Sending TX
How nonces are used
 Each account has a nonce value (account state data)
 Accounts start with nonce value 0
 TX: includes sender address and its nonce value
 TX can only be mined if:
− Account has sufficient funds
− TX nonce == current account nonce
 If TX is mined successfully: Nonce increased by 1
Ethereum Accounts and Nonces
What is gas?
 Special unit to pay fees to mining nodes
 Gas has price in Ethers (decouples computing costs and Ether price)
What fees?
 Computations performed by Ethereum Virtual Machine (EVM)
 EVM is working as long as there is gas
 Example 1: SHA3 computation costs 30 gas
 Example 2: EVM always terminates (stays in infinite loop until gas runs out)
Ethereum, Gas and TX Fees
Smart Contracts
What is a Smart Contract?
 Piece of (byte) code
 Is executed by the Ethereum Virtual Machine (EVM)
 Has an owner
 Has a life cycle
 Might have some purpose
Examples
1. The DAO
2. Flight delay insurance
3. «Truly» autonomous cars
Ethereum Smart Contracts
 Distributed venture capital fund
 Amount raised $150,000,000
 Largest crowdfunding project
 Successfully «attacked»
Attack Result: Ethereum hard fork
 ETH «true» blockchain
 ETC «forked» blockchain
The DAO (2016)
 Involves Oraclize service to access flightstats.com
Flight Delay App
 Smart contract to ordering vehicle to transport goods/people
 Smart contract to pay for energy/services
«Truly» Autonomous Cars
Deploying and using Smart Contracts
1. Write contract in high level language (eg. Solidity)
2. Compile contract to EVM byte-code
3. Pack byte code into a contract creation TX and sent to the network
4. The TX gets ist own contract account
5. Contract account has address, balance, nonce and holds byte code
6. Invoke methods using calls (free) or transactions (cost gas)
Smart Contracts Life Cycle
«Hello World» (greeter.sol)
greeter.sol ++
- additional state
- ‘payable’
Solidity Compiler (online)
byte code (EVM)
to deploy contract
Deploy script (JS)
Deploy (Console)
Contract address
Successs 
From Solidity to Java Contract Class
1. Compile greeter.sol (e.g using online compiler)
 greeter.bin, greeter.abi
2. Create contract wrapper class (use Web3j command line tool)
 Greeter.java
1. Use Greeter.java in your Java code
web3j: greeter.sol  Greeter.java
Generated Contract Wrapper
Live Cycle in Java
Deployment
Trading-Network Demo
Ethereum, web3j, Eclipse Scout
Use Case
 Currency Hedging: Buy orders and Sell orders (€ / US$)
 Classical Business App
− Idendity Management for mapping real persons BC addresses
− User Interface
 Blockchain Benefits
− Efficiency: No central organization/infrastructure
− Trust: Tampering-proof ledger, trust by blockchain
Trading Network Demo
 Plain Java Application Model
 Multi-Device Support
 HTML5/CSS3 Rendering
Eclipse Scout
Business Application Framework
PostgreSQLEthereum Client
TestRPC
web3
Eclipse Scout
Backend
web3j JDBC
Eclipse Scout
UI (web application)
Resources
What next?
Gist
 Cool new technology, including much hype 
 Internet of decentralized trust
Blockchain Technology is great for
 Efficient value exchange for untrusted environments
 Pushes distributed business models
 Option for the «unbanked»
Current Challenges
 Privacy
 Scalability
 Maturity (blockchain still in ist infancy)
Blockchain Summary
Socalizing
 Go to talks
 Join meetups (Bitcoin Meetup Switzerland, Blockchain Meetup Switzerland,
Crypto Valley Forum, …)
Increase Context
 Youtube, Blogs, Twitter, …
Doing
 GitHub (web3j/web3j, matthiaszimmermann/web3j_demo, …)
Next Steps
«Recipe»
1. Curious about new technologies? Take yourself seriously!
2. Invest some of your time
3. Take advantage of your education options (time, money, …)
4. Building small teams makes it even more fun
5. Create value for your employer (internal, external)
6. Do it!
Everybody can do this 
Thanks!
@ZimMatthias

Blockchain, Ethereum and Business Applications

  • 1.
    Blockchain, Ethereum and BusinessApplications @ZimMatthias Matthias Zimmermann BSI Business Systems Integration AG
  • 3.
  • 4.
  • 5.
    First decentralized digitalcurrency • By «Satoshi Nakamoto» • White Paper 2008 • Open Source Software 2009
  • 7.
    Coffee at Bob‘s Address Amount[B] Name Recipient 1GdK9UzpHBzqzX2A9JFP3Di4weBwqgmoQA 0.015 Bob's Café Source: «Mastering Bitcoin», Andreas M. Antonopoulos
  • 8.
    Addresses corresponds to«Accounts» Encoded Numbers  Example: 1GdK9UzpHBzqzX2A9JFP3Di4weBwqgmoQA  Derived from a private Key  Private key is 256-Bit random number Getting, using and loosing Accounts  Create your account with «Coin, Paper and Pencil»  No ID required, no showing up at local branch, …  To send Bitcoins you need your private Key  You loose your private key  you loose your money What is a Bitcoin Address?
  • 9.
     Bitcoin network confirmscoffee TX after ~ 10 min.  TX Elements The Coffee Transaction Bob’s Address Coffee Price My Address Link to TX Block Screenshot: blockchain.info Change (back to me) TX Fee Coffee TX
  • 10.
     Block #277316 includescoffee TX  Block Elements Genesis Block TX Blocks and the Blockchain 419 TX (€495,000) Link to revious Block#277316 #277315 #2 #1 Screenshot: blockchain.info Block Hash – do you see the leading zeros?
  • 11.
    From Transactions toBlocks (Mining)
  • 12.
    1. New TXare propagatet through Bitcoin peer-to-peer network 2. Bitcoin client verifies new TX and adds it to local «mempool» 3. Client starts to «mine» transactions: − Assemble TX from mempool to block candidate − Starts to solve the block candidate’s crypto challenge − Computes MANY hashes to solve the crypto challenge − Client solving the challenge first, gets block reward and all TX fees 3. Winning client sends the new block to its peers 4. Arrival of new block triggers the next challenge From Transactions to Blocks (Mining) Creation of new Bitcoins
  • 13.
    1.5 x 1018 IGraph:blockchain.info Bitcoin Mining Today  Mining-pools: Include many ASIC computers (PC way too slow)  AntMiner: 10,000x faster than PC, burns 10x more electricity  Energy Costs: # of hashes per KWh is central criteria + cooling(!) Hashing Power over the Years
  • 14.
    The Challenge  Miningclients build block candidates independently  Several new blocks might be found at the «same» time  Clients may receive new blocks that are inconsistent  The local copy of the blockchain may have forks The Solution  The «true» blockchain is defined by the highest cumulative PoW (difficulty)  By selecting the greatest-difficulty chain, eventual consensus is achieved  Miner majority vote defines the true chain  Miners «vote» for the true chain by deciding which block/fork to extend Distributed Consensus Mechanism Preventing Forks ? ?
  • 15.
    Attacking Bitcoin (anyPoW Blockchain) 1. Install more mining capacity than the rest of the world (>= 51%) 2. Censor/suppress unwanted TX 3. Mine a secret branch containing acceptable TX 4. Continue to mine until PoW of secret branch exceeds official branch 5. Broadcast secret branch to Bitcoin network 6. All Bitcoin clients will switch to this new branch Ok, this is kind of hard – but:  Miners earn ~1.2bn/year  HW cost to match Bitcoin mining capacity: ~ $400m (Antminer 9s) «Unhappy with some TX?» The 51% Attack
  • 16.
    Current Issues  IncreasingTX backlogs  TX confirmation can take hours (instead of 10’)  Increasing TX fees  «War» between Bitcoin Core and Bitcoin Unlimited (Scaling Debate)  Decreasing market share Bitcoin Challenges
  • 17.
  • 18.
  • 19.
    Bitcoin Success  Completelydecentral currency (no need for central banks)  Open Source (GitHub) and Open Data (complete TX history)  First successful implementation of any crypto currency  «Gold Standard» since 2009  Record price levels Bitcoin Challenges  Declining market share  Scaling debate/war Bitcoin Recap
  • 20.
  • 21.
  • 22.
    Decentralized Smart Contracts •2014 by Vitalik Buterin • Distributed Turing complete VM • Open source software 2014 • Is crypto currency too
  • 23.
    Ethereum vs Bitcoin CommonTraits  Local clients/nodes with complete blockchain (open data)  Concepts of addresses, transactions, mining  Virtual currency Ether  Open source Main Differences  Specification with different implementations (Bitcoin: single client)  Turing complete scripting (Bitcoin: very limited scripting)
  • 24.
     Ether iscurrency unit (1 Ether ~ 87$ 17.05.17)  Wei is smallest denomination (10-18 Ether)  TX mining: Proof of Work (PoW)  Distributed consensus like Bitcoin (true chain == highest cumulative PoW) Storing Information  Ethereum clients: Maintain blockchain data + state data  State data: Account balances + nonces  Transaction data: Ether transfers Ethereum as Virtual Currency Platform
  • 25.
    Ethereum and AppIntegration Ethereum Client Geth/TestRPC/… Ethereum Peer-to-Peer Network Interface http://localhost:8545 JSON-RPC JavaScript web3 web3j Java
  • 26.
    Ideal Development Setup Offline, repeatable, fast  Java (this is a JUG talk after all) We can have all this   Docker (repeatable, shareable)  TestRPC (offline + local blockchain /w immediate TX confirmations)  Web3j (Ethereum Java Library) Ethereum Hands-on
  • 27.
  • 28.
    Running TestRPC container Open shellin container Start node.js
  • 29.
    TestRPC initial accounts Getinitial balance New balance Send 123456789 Weis
  • 30.
     Java implementationof JSON-RPC client API  A couple of other features  Android support web3j: Ethereum and Java
  • 32.
  • 33.
    How nonces areused  Each account has a nonce value (account state data)  Accounts start with nonce value 0  TX: includes sender address and its nonce value  TX can only be mined if: − Account has sufficient funds − TX nonce == current account nonce  If TX is mined successfully: Nonce increased by 1 Ethereum Accounts and Nonces
  • 34.
    What is gas? Special unit to pay fees to mining nodes  Gas has price in Ethers (decouples computing costs and Ether price) What fees?  Computations performed by Ethereum Virtual Machine (EVM)  EVM is working as long as there is gas  Example 1: SHA3 computation costs 30 gas  Example 2: EVM always terminates (stays in infinite loop until gas runs out) Ethereum, Gas and TX Fees
  • 35.
  • 36.
    What is aSmart Contract?  Piece of (byte) code  Is executed by the Ethereum Virtual Machine (EVM)  Has an owner  Has a life cycle  Might have some purpose Examples 1. The DAO 2. Flight delay insurance 3. «Truly» autonomous cars Ethereum Smart Contracts
  • 37.
     Distributed venturecapital fund  Amount raised $150,000,000  Largest crowdfunding project  Successfully «attacked» Attack Result: Ethereum hard fork  ETH «true» blockchain  ETC «forked» blockchain The DAO (2016)
  • 38.
     Involves Oraclizeservice to access flightstats.com Flight Delay App
  • 39.
     Smart contractto ordering vehicle to transport goods/people  Smart contract to pay for energy/services «Truly» Autonomous Cars
  • 40.
    Deploying and usingSmart Contracts 1. Write contract in high level language (eg. Solidity) 2. Compile contract to EVM byte-code 3. Pack byte code into a contract creation TX and sent to the network 4. The TX gets ist own contract account 5. Contract account has address, balance, nonce and holds byte code 6. Invoke methods using calls (free) or transactions (cost gas) Smart Contracts Life Cycle
  • 41.
  • 42.
    greeter.sol ++ - additionalstate - ‘payable’
  • 43.
    Solidity Compiler (online) bytecode (EVM) to deploy contract Deploy script (JS)
  • 44.
  • 45.
    From Solidity toJava Contract Class 1. Compile greeter.sol (e.g using online compiler)  greeter.bin, greeter.abi 2. Create contract wrapper class (use Web3j command line tool)  Greeter.java 1. Use Greeter.java in your Java code web3j: greeter.sol  Greeter.java
  • 46.
  • 47.
  • 48.
  • 50.
  • 51.
    Use Case  CurrencyHedging: Buy orders and Sell orders (€ / US$)  Classical Business App − Idendity Management for mapping real persons BC addresses − User Interface  Blockchain Benefits − Efficiency: No central organization/infrastructure − Trust: Tampering-proof ledger, trust by blockchain Trading Network Demo
  • 52.
     Plain JavaApplication Model  Multi-Device Support  HTML5/CSS3 Rendering Eclipse Scout Business Application Framework
  • 53.
  • 56.
  • 57.
  • 58.
    Gist  Cool newtechnology, including much hype   Internet of decentralized trust Blockchain Technology is great for  Efficient value exchange for untrusted environments  Pushes distributed business models  Option for the «unbanked» Current Challenges  Privacy  Scalability  Maturity (blockchain still in ist infancy) Blockchain Summary
  • 59.
    Socalizing  Go totalks  Join meetups (Bitcoin Meetup Switzerland, Blockchain Meetup Switzerland, Crypto Valley Forum, …) Increase Context  Youtube, Blogs, Twitter, … Doing  GitHub (web3j/web3j, matthiaszimmermann/web3j_demo, …) Next Steps
  • 60.
    «Recipe» 1. Curious aboutnew technologies? Take yourself seriously! 2. Invest some of your time 3. Take advantage of your education options (time, money, …) 4. Building small teams makes it even more fun 5. Create value for your employer (internal, external) 6. Do it! Everybody can do this 
  • 61.

Editor's Notes

  • #3 Wieso ist das spannend? weshalb sich das anhören? Coole neue technologie Thema kräftig am wachsen Definitiv nicht nur spinnerei https://bitcoinfoundation.org/ https://www.ethereum.org/foundation https://www.hyperledger.org/ https://www.aegon.com/en/Home/Investors/News-releases/2017/blockchain-initiative-b3i-gains-truly-international-scope/ http://cryptovalley.swiss/ https://ww2.frost.com/files/cache/a701d7ea2011161d4eaeed6364153683_f16618.jpg
  • #4 Bei blockchain geht es nicht nur um software und technologie, sondern auch um viel geld https://coinmarketcap.com/currencies/ (accessed 8.5.17) https://en.wikipedia.org/wiki/List_of_countries_by_GDP_(PPP) (accessed 8.5.17)
  • #6 Starten wir mit Bitcoin
  • #7 tx https://blockchain.info/tx/a662f0c533686128770b2604f36ce2015cf68382ede8dbd8f19ef9f8f45c6777 account https://blockchain.info/address/1Mk6LVarnMtf9YtU316NqKQESM44C3Ja1e
  • #11 Bei hashwert für diesen block: vom miner gefundene hashwert. Hashwerte sehen üblicherweise zufällig aus, dass dieser wert mit so viel nullen beginnt ist kein zufall, der wurde vom bitcoin client gefunden, der diesen block gemint hat. Wir werden etwas später noch auf das mining kommen.
  • #12 https://blockchain.info/unconfirmed-transactions https://blockchain.info/address/199kWQQSMfUWRaLJ7mVGN6SQjEHegC3gqD
  • #14 http://www.coindesk.com/blockchain-immutability-myth/ https://shop.bitmain.com/market.htm?name=antminer_s9_asic_bitcoin_miner
  • #16 http://www.coindesk.com/blockchain-immutability-myth/
  • #17 http://www.trustnodes.com/2017/05/16/bitcoins-market-share-falls-below-half-of-all-digital-currencies https://blockchain.info/de/charts/mempool-size?timespan=all https://github.com/bitcoin/bitcoin https://github.com/BitcoinUnlimited/BitcoinUnlimited
  • #18 https://coinmarketcap.com/charts/ (bottom of page)
  • #19 http://www.coindesk.com/price/ (accessed 8.5.17) https://blockchain.info/
  • #21 https://github.com/bitcoin/bitcoin https://github.com/bitcoinbook/bitcoinbook
  • #25 https://forum.ethereum.org/discussion/304/what-is-wei https://ethereum.stackexchange.com/questions/326/what-are-the-pros-and-cons-of-ethereum-balances-vs-utxos https://media.consensys.net/technical-introduction-to-events-and-logs-in-ethereum-a074d65dd61e
  • #26 https://github.com/ethereum/wiki/wiki/JSON-RPC https://github.com/ethereum/wiki/wiki/JavaScript-API https://github.com/web3j/web3j
  • #28 https://github.com/matthiaszimmermann/web3j_demo
  • #29 cd /usr/lib/node_modules/ethereumjs-testrpc/ node var Web3 = require('web3') var web3 = new Web3() web3.setProvider(new Web3.providers.HttpProvider('http://localhost:8545')) web3.eth.coinbase web3.fromWei(web3.eth.getBalance(web3.eth.coinbase), "ether") web3.eth.accounts web3.fromWei(web3.eth.getBalance(web3.eth.accounts[1]), "ether") web3.eth.sendTransaction({from: web3.eth.coinbase, to:web3.eth.accounts[1], value: web3.toWei(0.5, "ether")}) web3.fromWei(web3.eth.getBalance(web3.eth.accounts[1]), "ether") https://github.com/matthiaszimmermann/web3j_demo
  • #31 https://docs.web3j.io/
  • #33 https://docs.web3j.io/
  • #34 https://docs.web3j.io/
  • #35 https://ethereum.stackexchange.com/questions/3/what-is-gas-and-transaction-fee-in-ethereum
  • #38 https://blog.daohub.org/ethereum-dao-hard-fork-likely-on-july-20th-9ee8e2c12619
  • #39 https://fdd.etherisc.com/ http://www.oraclize.it/ http://www.flightstats.com
  • #40 http://www.trustnodes.com/2017/04/29/germanys-energy-giant-launches-100s-ethereum-based-electric-cars-charging-stations (29.4.17) https://www.theverge.com/2017/2/21/14687346/uber-self-driving-car-arizona-pilot-ducey-california (21.2.17)
  • #44 https://ethereum.github.io/browser-solidity/#version=soljson-v0.4.11+commit.68ef5810.js
  • #45 cd /usr/lib/node_modules/ethereumjs-testrpc/ node var Web3 = require('web3') var web3 = new Web3() web3.setProvider(new Web3.providers.HttpProvider('http://localhost:8545')) var _greeting = 'hello world'; var greeterContract = web3.eth.contract([{"constant":true,"inputs":[],"name":"deposits","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"kill","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"greet","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"inputs":[{"name":"_greeting","type":"string"}],"payable":false,"type":"constructor"},{"payable":true,"type":"fallback"}]); var greeter = greeterContract.new( _greeting, { from: web3.eth.accounts[0], data: '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', gas: '4700000' }, function (e, contract){ console.log(e, contract); if (typeof contract.address !== 'undefined') { console.log('Contract mined! address: ' + contract.address + ' transactionHash: ' + contract.transactionHash); } }); greeter.address greeter.greet() greeter.deposits() web3.fromWei(web3.eth.getBalance(greeter.address), "ether") web3.eth.sendTransaction({from: web3.eth.coinbase, to:greeter.address, value: web3.toWei(0.5, "ether")}) web3.fromWei(web3.eth.getBalance(greeter.address), "ether") greeter.deposits()
  • #52 https://github.com/BSI-Business-Systems-Integration-AG/trading-network/tree/features/matthiaszimmermann/jugch_talk_2017
  • #57 https://www.ethereum.org/ https://github.com/ethereum/
  • #60 https://github.com/web3j/web3j
  • #63 cd ~/Desktop/oss/events/2017/jug_blockchain_2017 java DummyBitcoinMiner 1
  • #66 https://poloniex.com/
  • #68 https://blockchain.info/charts/avg-confirmation-time