bank

Overview

This is a simple smartcontract example. The bank itself is designed in solidity.

A client application designed in golang deploy a contract in a ethereum compatible blockchain network (Ganache, test net or GoQuorum). An easy way to test is installing Ganache (mentioned below).

Next, use the local golang client to deploy the contract and run the workload.

Requirements

Ethereum compatible blockchain network

Local development is easier with Ganache. Install it, then use the quickstart button to create the local testing network.

Once you have Ganache (or another ethereum blockchain) working, make sure to get

1. the connection url (http or ws)
2. private key.

Using Ganache, you can easliy get this information from interface by right clicking in one of the generated accounts.

Golang

Make sure you have Go installed. Installing go is beyond the scope of this document. An easy way to install it is using ASDF with Go plugin. Other plugins are available here. We used go version 1.16.7.

You will also need go ethereum source (go-ethereum) and tools (abigen) required to build our client application.

go get -u github.com/ethereum/go-ethereum@v1.10.9

After downloading the code to gopath, you are required to build the tools: find where the source is installed:

go env GOPATH

Access the directory to build the source. (the location below can be slightly different for you)

cd $(go env GOPATH)/pkg/mod/github.com/ethereum/go-ethereum@v1.10.9
make
make devtools

Note: if you find a compilation error, that's likelly permission denied, simply create a bin dir inside build dir.:

mkdir -p $(go env GOPATH)/pkg/mod/github.com/ethereum/go-ethereum@v1.10.9/build/bin

also try to set permissions to it

sudo chmod -R u+rw $(go env GOPATH)/pkg/mod/github.com/ethereum/go-ethereum@v1.10.9 

If it fails (happened in osx big sur), open the path with finder and set permissions using GUI.

After that, the abigen command must be available.

Build the blockchain client

Assuming the steps of Requeriments section was complete, you can create the client by running the build script.

bash buildstubs.sh

Deploy the smartcontract

You can connect to the endpoints with http and ws sockets. However, tracking events are only supported via websockets (for that, just replace http with ws and set the correct port).

Since Ganache run locally, you can replace the IP for 127.0.0.1. For Quorum, replace the IP with the corresponding one for the actual server node.

It returns a contract address (use it for printing the counter at the end)

./bank deploy --host 127.0.0.1 --port 8545 --key 1be3b50b31734be48452c29d714941ba165ef0cbf3ccea8ca16c45e3d8d45fb0

should output:

INFO[0000] Connecting to ethereum network...
Nonce: 0
Gas price: 20000000000
Transaction address: 0x843ef8f573414ae4631cf63ff95a05be90bd10f57c3b300abd5adcd854fae077
Contract address 0x24C4fbcd6fa5360Cd1AEA2CeD9F1D7a0cdbc1897
Contract deployed

transfer funds to an account

./bank transfer --host 127.0.0.1 --port 8545 --contract 0x6C07e5999bcc45d1276fda4E216227b058cac45b --keys fb7853d9282ba852c850e9f734265ae757f85975cd7e4ef29a362b76e307d797,3e7c5b66041123f0327822100c3a242ad69a9b310381e43dda850226d3e3dca8,50b61c0564bb8a752530290ab908aed7fa1875676256f6b86aebedde6e69c5d0 --wallets 0x819243165Fa08e5EA840e5d7E3b8b9ae3FBee77b,0xA79b91De96238a6aA50375BBa01BCD3D82a9A7DE,0x23635FFeDd962b932342C48C444955806E3EFE22  --money 100000000000000000 --origin 0 --target 1

This will transfer the default 1 eth from account 0 to account 1 from the account list informed (keys and wallets)

Run workload

It creates a contract and run operations on it

./bank workload --host 127.0.0.1 --port 8545 --operation transfer --keys fb7853d9282ba852c850e9f734265ae757f85975cd7e4ef29a362b76e307d797,3e7c5b66041123f0327822100c3a242ad69a9b310381e43dda850226d3e3dca8,50b61c0564bb8a752530290ab908aed7fa1875676256f6b86aebedde6e69c5d0 --wallets 0x819243165Fa08e5EA840e5d7E3b8b9ae3FBee77b,0xA79b91De96238a6aA50375BBa01BCD3D82a9A7DE,0x23635FFeDd962b932342C48C444955806E3EFE22 --money 1000000000000000000

operation can be transfer, mixed or deploy target is optional. if not informed an origin and target are randomly selected from the begining and issued operations during the workload.

be warned for funds, the program crash if funds are not sufficient.