Notes on Blockchain

Posted on | In , , ,

Lets split some notes about learning to work with blockchain.

My First Ethereum Network

Following the example from hackernoon

Here’s an extract of what’s important for me in the process.

Create Nodes

jaci@geth:~/devnet$ mkdir node1 node2

jaci@geth:~/devnet$ geth --datadir node1/ account new
INFO [03-14|15:19:48] Maximum peer count                       ETH=25 LES=0 total=25
Your new account is locked with a password. Please give a password. Do not forget this password.
Passphrase:
Repeat passphrase:
Address: {f4ad40a428b02f7a45ce6fa9fc3f87c4cab20f0a}

jaci@geth:~/devnet$ geth --datadir node2/ account new
INFO [03-14|15:22:06] Maximum peer count                       ETH=25 LES=0 total=25
Your new account is locked with a password. Please give a password. Do not forget this password.
Passphrase:
Repeat passphrase:
Address: {cdd45d92a9b151b0eea54e70914ce5ea2dfdc249}
Note: save the passwords on ~/devnet/node{1,2}/password.txt, remember this is a testnet!

Create Genesis file (see hackernoon guide)

You should have now a few files like the following

devnet$ tree -L 2
.
├── accounts.txt
├── boot.key
├── genesis.json
├── node1
│   ├── geth
│   ├── keystore
│   └── password.txt
└── node2
    ├── geth
    ├── keystore
    └── password.txt

Initialize your nodes

devnet$ geth --datadir node1/ init genesis.json
devnet$ geth --datadir node2/ init genesis.json

Start BootNode

Once you’re done with genesis.json and initialized your nodes, you can start the BootNode

jaci@geth:~/devnet$ bootnode -nodekey boot.key -verbosity 9 -addr :30310
INFO [03-14|15:27:15] UDP listener up                          self=enode://42735281a2058b0eedcebf3fa579253e654dbdf945b89ac8a44fc4a3386bd14bca3f0cb19947a97f8a4303b8851b23189b297166c369ae45a7f90cb013c52c5e@[::]:30310

Start Nodes

Node 1
geth --datadir node1/ --syncmode 'full' --port 30311 --rpc --rpcaddr 'localhost' --rpcport 8501 --rpcapi 'personal,db,eth,net,web3,txpool,miner' --bootnodes 'enode://42735281a2058b0eedcebf3fa579253e654dbdf945b89ac8a44fc4a3386bd14bca3f0cb19947a97f8a4303b8851b23189b297166c369ae45a7f90cb013c52c5e@127.0.0.1:30310' --networkid 1515 --gasprice '1' -unlock '0xf4ad40a428b02f7a45ce6fa9fc3f87c4cab20f0a' --password node1/password.txt --mine
Node2
geth --datadir node2/ --syncmode 'full' --port 30312 --rpc --rpcaddr 'localhost' --rpcport 8502 --rpcapi 'personal,db,eth,net,web3,txpool,miner' --bootnodes 'enode://42735281a2058b0eedcebf3fa579253e654dbdf945b89ac8a44fc4a3386bd14bca3f0cb19947a97f8a4303b8851b23189b297166c369ae45a7f90cb013c52c5e@127.0.0.1:30310' --networkid 1515 --gasprice '0' --unlock '0xcdd45d92a9b151b0eea54e70914ce5ea2dfdc249' --password node2/password.txt --mine

Your First Transaction

First check which is your coinbase, on each node, run the following.

> eth.coinbase
"0xf4ad40a428b02f7a45ce6fa9fc3f87c4cab20f0a"

Send transaction

> eth.sendTransaction({'from':eth.coinbase, 'to':'0xcdd45d92a9b151b0eea54e70914ce5ea2dfdc249', 'value':web3.toWei(3, 'ether')})

"0xcb3ff42f865610e195b24402700223127d1d0caeea796847f0046e2c7cfaa071"

Get Transaction

> eth.getTransactionReceipt("0xcb3ff42f865610e195b24402700223127d1d0caeea796847f0046e2c7cfaa071")
{
  blockHash: "0x2d106099ed00f0ee6737a9573723a4fc5f4dc9f57cdae2042fd545cd20ca5cfb",
  blockNumber: 49,
  contractAddress: null,
  cumulativeGasUsed: 21000,
  from: "0xf4ad40a428b02f7a45ce6fa9fc3f87c4cab20f0a",
  gasUsed: 21000,
  logs: [],
  logsBloom: "0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  status: "0x1",
  to: "0xcdd45d92a9b151b0eea54e70914ce5ea2dfdc249",
  transactionHash: "0xcb3ff42f865610e195b24402700223127d1d0caeea796847f0046e2c7cfaa071",
  transactionIndex: 0
}

My first Ethereum SmartContract

Following the expample from Greeter

Solc on your machine

If you installed the compiler on your machine, you need to compile the contract to acquire the compiled code and Application Binary Interface.

solc -o target --bin --abi Greeter.sol

This will create two files, one file containing the compiled code and one file creating the Application Binary Interface in a directory called target.

Basic Commands

> net.listening
true

> net.peerCount
4

> admin.peers

> admin.nodeInfo

Basic Curl Requests

Admin Peers
curl -X POST --data '{"jsonrpc":"2.0","method":"admin_peers","params":[],"id":0}' http://localhost:22000 | json_pp > kkk

curl -X POST --data '{"jsonrpc":"2.0","method":"admin_peers","params":[],"id":0}' http://localhost:22000
NodeInfo
curl -X POST --data '{"jsonrpc":"2.0","method":"admin_nodeInfo","params":[],"id":0}' http://localhost:22000
TxPool status and content
curl -X POST --data '{"jsonrpc":"2.0","method":"txpool_status","params":[],"id":0}' http://localhost:22000

curl -X POST --data '{"jsonrpc":"2.0","method":"txpool_content","params":[],"id":0}' http://localhost:22000
Eth Syncinc, mining, gasPrice and blockNumber
curl -X POST --data '{"jsonrpc":"2.0","method":"eth_syncing","params":[],"id":1}'

curl -X POST --data '{"jsonrpc":"2.0","method":"eth_mining","params":[],"id":71}'

curl -X POST --data '{"jsonrpc":"2.0","method":"eth_gasPrice","params":[],"id":73}'

curl -X POST --data '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":83}' http://localhost:22000