j-node: August 2017

Tuesday, August 15, 2017

random quote of the day

technology A short quote on the acceleration of technological breakthroughs at breakneck speed:

The information society has been brought about by the fastest growing technology in history. No previous generation has ever been exposed to such an extraordinary acceleration of technological power over reality, with the corresponding social changes and ethical responsibilities. Total pervasiveness, flexibility, and high power have raised ICT to the status of the characteristic technology of our time, factually, rhetorically, and even iconographically.

The computer presents itself as a culturally defining technology and has become a symbol of the new millennium, playing a cultural role far more influential than that of mills in the Middle Ages, mechanical clocks in the seventeenth century, and the loom or the steam engine in the age of the Industrial Revolution.

Taken from The Philosophy of Information, Luciano Floridi, 2011, pages 4 and 5.

Tuesday, August 1, 2017

How To ICO

token fun A little tutorial showing you how to create your own ERC20 tokens using Solidity on the Ethereum testnet Rinkeby.

Preface

To get started, you need Ubuntu Linux running. An easy way is to

install VirtualBox on your machine;
install Ubuntu there.

Then you need to install

Solidity (object-oriented programming language for writing smart contracts);
Geth (command line interface for running a full ethereum node implemented in Go).

To do this, execute the following:

$ sudo apt-get install software-properties-common
$ sudo add-apt-repository -y ppa:ethereum/ethereum
$ sudo apt-get update
$ sudo apt-get install geth solc

Check your installation:

$ solc --version
$ geth version

See more details here.

Solidity Deployment

Synchronize blockchai:

$ geth --rinkeby --fast

This will take a couple of minutes. Once you see something like this in the terminal, you are up to date (note that an average block time is 15s):

    INFO [08-01|14:53:24] Imported new chain segment blocks=1 txs=1
    mgas=0.021  elapsed=1.998ms   mgasps=10.505  number=638703
    hash=273388…bd5211

Then you can CTR-C.

To launch the CLI:

$ geth attach $HOME/.ethereum/rinkeby/geth.ipc

Create an address (account) on the Rinkeby testnet:

$ geth --rinkeby account new

Enter password and save address.

Start Geth:

$ geth --rinkeby --rpc --rpccorsdomain '*' --rpcapi 
"eth,net,web3,personal" --unlock 0 --password <(echo XXX)

Go to:

http://ethereum.github.io/browser-solidity/
change "Environment" (top right) from "JavaScript VM" to " Web3 Provider" (uses http://localhost:8545).

Get ETH:

Go to https://www.rinkeby.io/ and click "Crypto Faucet".
You need a GitHub account.
Login to create a Gist: description and filename can be anything, however, the first line (starting with "1") needs to contain the address you generated above, preceded by "0x" (see example).
Refresh the GUI at http://ethereum.github.io/browser-solidity/ (and choose "Web3 Provider" again)

Now you should have an account balance showing a few ether.

Deploy Test Contract

Set up:

In http://ethereum.github.io/browser-solidity/ add a new contract (plus sign top left).
Fill in example code from here.
Click "Create" (orange/pink button right-hand side).
Wait for transaction to be mined.
Check terminal synchronizing blocks: you should see the address of the new contact "contract=0x0498b6289f48e28124ec23c30993fcf59af22092".
You should have less ether (top right).
Check contract address in https://rinkeby.etherscan.io/.

Play:

You should have buttons in the browser on the right-hand side (http://ethereum.github.io/browser-solidity/) corresponding to the getter and setter functions.
Enter in "set": 2,"MyAddr",42
Entering 2 in "getAmount" or "getAddr" should return "42" and "MyAddr", respectively.

Create ERC20 Token

Copy code from here into http://ethereum.github.io/browser-solidity/.
Deploy contract with "Create" button ("browser/myToken.sol/MyToken").
Check "totalSupply" button.
Check your balance by putting your account address you generated with Geth above into the "balanceOf" field (right-hand side). NB: address is in quotes and add "0x" if missing in the beginning of the string.
Check contract address (from synchronization terminal or "Copy address" button in browser) in

With the parity wallet (stop synchronizing terminal and go to http://127.0.0.1:8180/ ) ERC20 tokens can be stored. Create a new wallet address. Stop parity and restart Geth. Click " transfer" button with your parity address in quotes and some amount.

Voila, you just did an ICO and transferred some tokens.

See my example token (original address and my parity wallet).

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