# Development Environment and Tools {% hint style="info" %} Before getting started, you can apply for testnet **ONG** tokens that will be used for invoking any contracts you deploy over at the [**faucet here**](https://developer.ont.io/). {% endhint %} {% hint style="warning" %} The value of gas price for a transaction must be in multiples of 10^9. The minimum value is 2500\*10^9. {% endhint %} ## Development Environment and Tools EVM smart contracts are written using [Solidity](https://docs.soliditylang.org/en/v0.8.6/). You can reuse existing Ethereum contract frameworks to develop and deploy EVM contracts. ### Remix [Remix IDE](https://remix.ethereum.org/#optimize=false\&runs=200\&evmVersion=null\&version=soljson-v0.8.1+commit.df193b15.js) is an open source development environment for EVM contracts. Remix IDE documentation is [here](https://remix-ide.readthedocs.io/en/latest/). We will now go through an example of a Hello World contract development using Remix. #### **Initialize Remix** First, locate and activate "Solidity Compiler" and "Deploy and Run Transactions" in PLUGIN MANAGER. [![image-20210526142630046](https://github.com/ontio/ontology/raw/master/docs/specifications/evm_refernce/tutorial/image-20210526142630046.png)](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/tutorial/image-20210526142630046.png) Then, select Solidity environment. Create a new file and name it HelloWorld.sol. Then copy the code of [Hello World contract](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/contract-demo/helloworlddemo/helloworld.sol) and paste it in the file just created. [![image-20210526143301031](https://github.com/ontio/ontology/raw/master/docs/specifications/evm_refernce/tutorial/image-20210526143301031.png)](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/tutorial/image-20210526143301031.png) #### **Compile Contract** Click on the Solidity Compiler button, select compiler version to 0.5.10 and start compiling HelloWorld.sol #### **Deploy Contract** The contract is ready to deploy on Ontology after compiling. Here we deploy it on Ontology TestNet. {% hint style="info" %} **Note**: MetaMask must be configured for Ontology before you deploy the contract. {% endhint %} Select "Custom RPC" in MetaMask networks settings. Fill in and save the info below. * **Network name:** Ontology TestNet * **Node URL:** `https://polaris1.ont.io:10339` or `https://polaris2.ont.io:10339` or `https://polaris3.ont.io:10339` or `https://polaris4.ont.io:10339` * **Chain ID:** 5851 * **Blockchain Explorer URL:** "" [![RemixIDE\_Step1](https://github.com/ontio/ontology/raw/master/docs/specifications/evm_refernce/tutorial/metamask_networks.png)](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/tutorial/metamask_networks.png) Finally, select "Injected Web3" in Remix. Click "Deploy" to finish. [![deploy contract](https://github.com/ontio/ontology/raw/master/docs/specifications/evm_refernce/tutorial/remix_deploy.jpg)](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/tutorial/remix_deploy.jpg) #### **Invoke Contract** Now you can call the method in this contract. The string `hello` is saved in the contract when you deploy it, you can call the method `message` to query this string: [![invoke contract](https://github.com/ontio/ontology/raw/master/docs/specifications/evm_refernce/tutorial/remix_invoke.jpg)](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/tutorial/remix_invoke.jpg) ### Truffle Truffle offers tools and frameworks for EVM contract development, testing and management. You can find more details [here](https://www.trufflesuite.com/docs/truffle/quickstart). Now we will demonstrate how to use Truffle with this [test code](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/contract-demo/truffledemo). #### **Install Truffle** First, initialize and install dependencies. * [Node.js v8+ LTS and npm](https://nodejs.org/en/) (comes with Node) * [Git](https://git-scm.com/) Then run this command to install Truffle. ``` npm install -g truffle ``` #### **Configure truffle-config** * Create a new `.secret` to store the mnemonic phrase or private key (which can be found in MetaMask). * Edit the code of truffle-config as below. ```javascript const HDWalletProvider = require('@truffle/hdwallet-provider'); const fs = require('fs'); const mnemonic = fs.readFileSync(".secret").toString().trim(); module.exports = { networks: { ontology: { provider: () => new HDWalletProvider(mnemonic, `http://polaris2.ont.io:20339`), network_id: 5851, port: 20339, // Standard Ethereum port (default: none) timeoutBlocks: 200, gas:800000, skipDryRun: true } }, compilers: { solc: { version: "0.5.16", // Fetch exact version from solc-bin (default: truffle's version) docker: false, // Use "0.5.1" you've installed locally with docker (default: false) settings: { // See the solidity docs for advice about optimization and evmVersion optimizer: { enabled: true, runs: 200 }, evmVersion: "byzantium" } } } }; ``` #### **Deploy Contract** Run this command to deploy the contract on the Ontology network. ``` truffle migrate --network ontology ``` If successful, you will see the result below. {% hint style="warning" %} **Note:** Avoid using ETH units (e.g. wei, gwei, ether, etc.) when writing test scripts. {% endhint %} ``` Compiling your contracts... =========================== > Everything is up to date, there is nothing to compile. Starting migrations... ====================== > Network name: 'ontology' > Network id: 12345 > Block gas limit: 0 (0x0) 1_initial_migration.js ====================== Replacing 'Migrations' ---------------------- > transaction hash: 0x9019551f3d60611e1bc6b323f3cf3020d15c8aeb06833d14ff864e24622884aa > Blocks: 0 Seconds: 4 > contract address: 0x53e137A51CfD1E1b088E0d921eB5dBCF9cFa955E > block number: 6264 > block timestamp: 1624876467 > account: 0x4e7946D1Ee8f8703E24C6F3fBf032AD4459c4648 > balance: 0.00001 > gas used: 172969 (0x2a3a9) > gas price: 0 gwei > value sent: 0 ETH > total cost: 0 ETH > Saving migration to chain. > Saving artifacts ------------------------------------- > Total cost: 0 ETH 2_deploy_migration.js ===================== Replacing 'HelloWorld' ---------------------- > transaction hash: 0xf8289b96f2496a8c940ca38d736a554a90f64d927b689921781619499906721b > Blocks: 0 Seconds: 4 > contract address: 0xfbff9bd546B0e0D4b40f6f758847b70050d01b37 > block number: 6266 > block timestamp: 1624876479 > account: 0x4e7946D1Ee8f8703E24C6F3fBf032AD4459c4648 > balance: 0.00001 > gas used: 243703 (0x3b7f7) > gas price: 0 gwei > value sent: 0 ETH > total cost: 0 ETH hello contract address: 0xfbff9bd546B0e0D4b40f6f758847b70050d01b37 > Saving migration to chain. > Saving artifacts ------------------------------------- > Total cost: 0 ETH Summary ======= > Total deployments: 2 > Final cost: 0 ETH ``` ### Hardhat Hardhat is an Ethereum development environment. We will use this [test code](https://github.com/ontio/ontology/blob/master/docs/specifications/evm_refernce/contract-demo/hardhatdemo) as an example and demonstrate how to use Hardhat. #### **Install Hardhat** Please refer to [Hardhat doc](https://hardhat.org/getting-started/) for details on this step. #### **Configure hardhat-config** * Create a new `.secret` file to save your private key. * Update the code of hardhat.config.js as shown below: ```javascript require("@nomiclabs/hardhat-waffle"); const fs = require('fs'); const privateKey = fs.readFileSync(".secret").toString().trim(); module.exports = { defaultNetwork: "ontology_testnet", ontology_testnet: { url: "http://polaris2.ont.io:20339", chainId: 5851, gasPrice:2500000000000, gas:2000000, timeout:10000000, accounts: [privateKey] } }, solidity: { version: "0.8.0", settings: { optimizer: { enabled: true, runs: 200 } } }, }; ``` **Deploy Contract** Run this command in root of the project directory to deploy the contract on Ontology Chain: ``` $ npx hardhat run scripts/sample-script.js --network ontology_testnet ``` The result looks like this: ``` sss@sss hardhatdemo % npx hardhat run scripts/sample-script.js --network ontology_testnet RedPacket deployed to: 0xB105388ac7F019557132eD6eA90fB4BAaFde6E81 ``` ## Network Info ### Network Types **MainNet** | Item | Description | | -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | NetworkName | Ontology MainNet | | chainId | 58 | | Gas Token | ONG Token | | RPC |

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| | Block Explorer | | **TestNet** | Item | Description | | -------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | NetworkName | Ontology TestNet | | chainId | 5851 | | Gas Token | ONG Token | | RPC |

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| | Block Explorer | | {% hint style="info" %} Ontology EVM contracts consume ONG as gas fee for execution. You can apply for TestNet ONG [here](https://developer.ont.io/). {% endhint %} ### EVM Assets on Ontology | Name | Address | | ---- | ------------------------------------------- | | ONG | 0x00000000000000000000000000000000000000000 | ### OEP-4 Assets Please refer to this [link](https://explorer.ont.io/tokens/oep4/10/1#). --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.ont.io/guides-and-tutorials/development-guides/smart-contract-dev/evm-contract/development-environment-and-tools.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.