Ethereum under the Hood, intro for developers as preparation for Blockchain Hackathon (Delft, December 7th 2016)
- 2. Who are we? • Joris Bontje • @mids106 • http://OneUp.Company • Pascal Van Hecke • @vanheckeinfo • http://Tokenengineers.com
- 3. Who are we? • Joris Bontje • @mids106 • http://OneUp.Company • Pascal Van Hecke • @vanheckeinfo • http://Tokenengineers.com
- 5. Programming in Bitcoin • Contains a deliberately simple scripting language • A transaction = locking Bitcoin and describing how it can be unlocked • Examples: • Multisig: multiple signatures are needed to unlock • CheckLocktimeVerify: Bitcoin only spendable at some point in future • ….
- 7. Programming in Bitcoin • Contains a relatively simple scripting language • A transaction = locking Bitcoin and describing how it can be unlocked • Examples: • Multisig: multiple signatures are needed to unlock • CheckLocktimeVerify: Bitcoin only spendable at some point in future • …. More ”opcodes”, more functionality Altcoin/Metacoin X
- 9. Ethereum: anything is programmable “Classic “ blockchains • Addresses • Balance with “native” coin • Transactions and blocks Ethereum: • Addresses • … • … • Balance with Ether • … • Transactions and blocks • … • …
- 10. Ethereum: anything is programmable “Classic “ blockchains • Addresses • Balance with “native” coin • Transactions and blocks Ethereum: • Addresses • + data storage • + code • Balance with Ether • … • Transactions and blocks • … • …
- 14. Ethereum: anything is programmable “Classic “ blockchains • Addresses • Balance with “native” coin • Transactions and blocks Ethereum: • Addresses • + data storage • + code • Balance with Ether • … • Transactions and blocks • … • …
- 16. Ethereum: anything is programmable “Classic “ blockchains • Addresses • Balance with “native” coin • Transactions and blocks Ethereum: • Addresses • + data storage • + code • Balance with Ether • + application-specific tokens with specific behaviour • Transactions and blocks • … • …
- 17. Ethereum: anything is programmable “Classic “ blockchains • Addresses • Balance with “native” coin • Transactions and blocks Ethereum: • Addresses • + data storage • + code • Balance with Ether • + application-specific tokens with specific behaviour • Transactions and blocks • + creation of contract code • + calling contract code
- 20. Slow and primitive, but… Promise: A 15-year old can deploy business logic that is: • Verifiable • Immutable • Untamperable • Untouchable
- 27. Smart contract pattern 1 Lock thing of value in contract • Native crypto • Tokens representing value… or abilities 2 Contract code determines redistribution 3 Based on information that is not yet known • Randomness • Actor • “Oracle”
- 28. Solidity
- 32. Compiles to EVM bytecode TXVALUE PUSH 25 PUSH 10 PUSH 18 EXP MUL LE NOT PUSH 34 JMPI STOP PUSH 34 JMP PUSH 0 TXDATA SLOAD NOT PUSH 0 TXDATA PUSH 1000 LT NOT MUL NOT NOT PUSH 34 JMPI STOP PUSH 1 TXDATA PUSH 0 TXDATA SSTORE
- 40. web3
- 42. web3 - Javascript API // creation of contract object var MyContract = web3.eth.contract(abi); // initiate contract for an address var myContractInstance = MyContract.at('0x78e97bcc5b5dd9ed228fed7a4887c0d7287344a9'); var result = myContractInstance.myConstantMethod('myParam'); console.log(result) // '0x25434534534’ myContractInstance.myStateChangingMethod('someParam1', 23, {value: 200, gas: 2000}, function(err, result){ ... });
- 49. Clients
- 56. Resources