A Truffle repository that:
- Compiles and deploys a contract
and a server that:
- Interacts with the simple contract
The Ethereum account used here in config.js is only for development purposes and only used in Ropsten network. Do not share your account seed(mnemonic) publicly.
Install truffle globally by:
npm i -g truffle
If you'd like you can install truffle locally with npm i truffle and run by node_modules/.bin/truffle
Just bear in mind having an npm script such as npm run truffle does not parse the --network flag and causes errors.
npm install
When installing if you encounter an error similar to this:
npm ERR! code EISGIT
npm ERR! git /{$HOME}/Desktop/repos/simple-eth-server/node_modules/web3-providers-ws/node_modules/websocket: Appears to be a git repo or submodule.
Remove the .git folder in websocket. This is due to truffle-hdwallet-provider using an older version of web3:
rm -r node_modules/web3-providers-ws/node_modules/websocket/.git
truffle compile
This will create artifacts in /build/contracts/ These are files which describe the contract addresses, the networks on which the contracts have been deployed and the functions which contracts have.
These *.json files contain descriptions of their respective smart contracts. These files enables Truffle to create a JavaScript wrapper for communicating with the smart contract. For example, when you call contract.address in your JavaScript code, the Truffle framework reads the address from the *.json file and enables effortless transitions between contract versions and networks.1
You can deploy the contract to any network you'd like. In this example we will be using the Ropsten network. Deploy with
truffle migrate --network ropsten
Run the express server with
node app.js
You can access the server at http://localhost:3000/
| Endpoints | Function | Type | Body | |
|---|---|---|---|---|
| /getAccounts | Returns accounts associated with the seed provided to the wallet | GET | ||
| /getNumber | Returns the number as response | GET | ||
| /setNumber | Sets the stored number in the contract to the provided number. Prints the result of the transaction on the backend console. | POST | { number: uint } | |
| /getString | Returns the string as response | GET | ||
| /setString | Sets the stored string in the contract to the provided string. Prints the result of the transaction on the backend console. | POST | { string: string } |
We are using Infura as our provider. It is described as:
Infura is a hosted Ethereum node cluster that lets your users run your application without requiring them to set up their own Ethereum node or wallet.
To interact with the Ethereum blockchain we need to run a full node using a client like parity or geth. This is pretty inconvenient as we need to download the whole blockchain and simulate it since the genesis block. Instead we can rely on providers that will forward our transactions to the network and let us call functions from contracts. It is a method for connecting to the Ethereum network without having to run a full node. Infura provides endpoints to interact with blockchain.
To deploy via Infura you'll need a wallet provider (like truffle-hdwallet-provider) to sign your transactions before they're sent to a remote public node.