A step-by-step guide that explains how to create a SmartContract, used for fundraising, where each donation can also contain a text message. The SmartContract, written in Solidity, has been interfaced with two distinct web applications, one in writing and one in reading, made in Java using MetaRing. It also explains how to build a private Ethereum network.

1. Hello!
http://telethon.raspibo.loc
SSSID: blockchian@rapibo password: domotica

2. Telethon
http://telethon.raspibo.loc
Tot: 100 eth
http://screen.raspibo.loc
Ethereum Blockchain (Private)
Raspibo SmartContract

3. About Me
Ing. Marco Vasapollo
C. E. O. & Founder @ MetaRing
C. E. O. & Founder @ Aequalitam Foundation
Mail: ceo@metaring.com
Skype: marco.vasapollo
https://www.metaring.com
https://www.aequalitam.org

4. CryptoCurrencies
• Same money transfer info for each peer
• locally accessible
• anytime anywhere
• Public
• Secure
• by collective calculation verification with
reward
Decentralized Ledger:

5. How it works
Alice
Bob
1
2
3
4
5
6
7

6. Blockchain
• Same data for each peer
• locally accessible
• anytime anywhere
• Public
• Secure
• by collective consensus behavior
Decentralized Ledger:
Not just money transfer!

7. SmartContract
• “Wallet of a robot”
• Receives and sends back data (money and/or info)
• Multiple functionalities
• Custom behavior to blockchain

8. How it works
RaspiBOTelethon.sol
RaspiBOTelethon.binRaspiBOTelethon.abi
Source file, written in solidity
Solidity Compiler
Application
Binary
Interface
(A JSON File
Useful to “read”
The binary) 0101
Ethereum
Blockchain0x0abde13f….
Wallet Address in the blockchain
Your Application
1.
2.
3a.
4.
3b.
5.
6.
Classic binary file

9. https://ethereum.github.io/browser-solidity/

10. https://ethereum.github.io/browser-solidity/

11. https://ethereum.github.io/browser-solidity/
ABI
BINARY
Plain,Asynchronous Javascript code
Copy and paste code into
“install.js” file

12. Install contract

13. MIST
https://github.com/ethereum/mist/releases

14. Private Ethereum Network
1. Install Geth: https://github.com/ethereum/go-ethereum
2. bootnode --genkey boot.key
3. bootnode --nodekey=“boot.key”  “enode://181fecd2...8dabb@127.0.0.1:30301”
4. genesis.json:
{
"config": {
"chainId": 10,
"homesteadBlock": 0,
"eip155Block": 0,
"eip158Block": 0
},
"difficulty": "0",
"gasLimit": "999999999",
"alloc": {
"b8830394f60896d07d71baa485639101ccb6fdf6": { "balance": "300000000000000000000000" }
}
}
Id of the network, to identify that is a private blockchain
Pre-Mined wallets
Amount expressed in wei
1 eth = 10000000000000000000 wei

15. Private Ethereum Network
5. geth --datadir “data00”--verbosity 0 init genesis.json
6. geth --networkid 10
--nodiscover –datadir “data00”--verbosity 0
--exec `"if(eth.accounts.length === 0){personal.newAccount('');}`" console
7. touch store.pass
8. geth --identity "Marco Node 00"--datadir "data00"--ipcpath 00
--rpcapi personal,db,eth,net,web3 --rpc --rpcport 8700 --rpccorsdomain "*"
--rpcaddr 0.0.0.0 --port 30400
--networkid 10 --maxpeers 3
--bootnodes "enode://181fecd2...8dabb@127.0.0.1:30301“
--unlock 0 --password store.pass --minerthreads 1 --mine

16. Web3 Java Wrapper
https://github.com/web3j/web3j
https://docs.web3j.io/
1. solc RaspiBOTelethon.sol --bin --abi --optimize -o ./
2. web3j solidity generate ./RaspiBOTelethon.abi ./RaspiBOTelethon.bin –o ./ -p org.raspibo.telethon
https://github.com/web3j/web3j/releases/tag/v3.1.1
solc comes with Geth

17. Screen

18. Screen

19. Client

20. Q&A