Building on BNB Smart Chain’s Optimistic Rollup Layer 2 - A Guide to Developing on opBNB

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5 Jan 2024

This article will be a comprehensive guide that I created to give developers, readers a thorough understanding of the BNB Smart Chain (BSC) and opBNB

This guide by me will go over the fundamentals of smart contracts, programming languages, and tools, as well as how to set up a development environment.

I will also cover the advanced topics like integration with BSC, cross-chain communication between opBNB and BSC, and Layer 1 and Layer 2 interaction use cases.

The guide is also intended to assist developers in building on opBNB and developing more efficient and scalable blockchain applications. It includes basic codes, commands or tutorials to help developers or readers understand and apply the concepts in their projects.

Lastly, whether you are a beginner, a reader, or new to crypto world or an experienced developer, I hope that this guide, which I created using references and hours of research for this competition, will provide you with the knowledge and tools you need to develop on opBNB and take your blockchain development skills to the next level.

Understanding BNB Smart Chain (BSC) and opBNB

BNB Smart Chain (BSC) is a popular layer 1 blockchain that has gained significant traction due to its speed, scalability, and low fees.

However, as the number of users and transactions on the platform continues to grow, the need for even greater scalability arises. This is where opBNB comes in - an optimistic rollup Layer 2 scaling solution that builds on top of BSC.

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OpBNB is a separate blockchain that is piggybacked on top of BSC. It uses an optimistic rollup technique, where transactions are bundled off-chain and verified on-chain.

This allows opBNB to achieve higher throughput than BSC alone, while still maintaining the security and integrity of the underlying chain.

The advantages of using opBNB are numerous:

Firstly, it provides much faster transaction times compared to BSC, with some opBNB transactions completing in under 10 seconds.

Secondly, it significantly reduces gas fees, as the bundled transactions are processed in a single block.

Finally, opBNB allows for more complex dApps and smart contracts to be built, as it provides a separate execution environment from BSC.

The relationship between BSC and opBNB

The interaction between BSC and opBNB is crucial to understanding how the two chains complement each other. opBNB acts as a layer 2 scaling solution, opportunistically bundling transactions off-chain and verifying them on-chain. This allows opBNB to achieve higher throughput than BSC alone, while still maintaining the security and integrity of the underlying chain.

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The interaction between Layer 1 (BSC) and Layer 2 (opBNB) occurs through the use of a bridge contract. This contract allows for the transfer of assets and data between the two chains, ensuring a seamless user experience.

The basics of smart contracts

Smart contracts are self-executing contracts with the terms of the agreement written directly into lines of code. They are an essential component of blockchain networks, as they facilitate trustless and automated interactions between parties.

Smart contracts are written in programming languages such as Solidity, which is the primary language for Ethereum and BSC smart contract development. Development tools such as Hardhat and Remix IDE provide an overview of the development process, including coding, testing, and deployment.

Programming languages and tools

Solidity is the primary language for Ethereum and BSC smart contract development. It is a statically typed language that is designed to compile to Binaries, Patterns, or Scripts.

Other development tools such as Hardhat and Remix IDE provides an overview of the development process, including coding, testing, and deployment.

Key-points:

Hardhat is a popular development environment that provides an intuitive interface for writing and testing smart contracts.

Remix IDE is a powerful integration of Remix and Hardhat that allows developers to write, test, and deploy smart contracts in a single environment.

Setting up the development environment

Initiating development on opBNB necessitates the installation of essential tools and configuring a local development environment.

Here are the steps you can follow:

Install Node.js and a code editor such as Visual Studio Code or Atom

Install Hardhat and Remix IDE by running the following commands

npm install -g hardhat
npm install -g remix-ide

Connect to opBNB testnet by running the following command

opbnb-cli --testnet

For doing "Test a deposit of BNB to opBNB" and "Connecting to opBNB" testnet alternatively, you can refer to this Medium Article

Smart contract development for opBNB

Writing a smart contract for opBNB involves structuring the code, defining functions, and deploying the contract to the opBNB testnet.

Here are the steps you can follow:

Start by defining the structure of your contract, including the variables functions that will be used

Write the function logic for your contract, including any storage or interaction with external data

Deploy your contract to the opBNB testnet by running the following command

opbnb-cli deploy

opbnb-cli deploy MyContract

Verify your contract with opBNBScan by running the following command

opbnb-cli scan

Deploying smart contracts on opBNB

Deploying smart contracts on opBNB involves several steps, including:

Creating a new directory for your contract and navigating to it in your terminal.

Writing your smart contract code using Solidity or another programming language.

Compiling your contract code into a binary format using the solc compiler.

Deploying your contract to the opBNB testnet using the opbnb-cli command.

Here is an example of how to deploy a simple smart contract on opBNB:

# create a new directory for your contract
mkdir my-contract

# navigate to the directory in your terminal
cd my-contract

# write your smart contract code in a file called 'MyContract.sol'
// include your contract code here

// compile your contract code into a binary format using solc
$ solc MyContract.sol -o MyContract.bin

// deploy your contract to the opBNB testnet
$ opbnb-cli deploy MyContract.bin

Once your contract is deployed, you can use the opbnb-cli command to verify it with opBNBScan. This will allow you to see the details of your contract, including its storage and functions.

Interacting with smart contracts

Once your smart contract is deployed, you can interact with it using a variety of tools and frameworks.

Here are some examples:

Writing scripts: You can write scripts to interact with your smart contract, using the Truffle framework to deploy and call your contract.

Using frontend frameworks: You can use frontend frameworks such as Reactjs or Angular to build a user interface for your smart contract. This will allow users to interact with your contract through a user-friendly interface.

Sending transactions: You can use the opbnb-cli command to send transactions to your smart contract, updating its state and executing its functions.

Querying contract data: You can use the opbnb-cli command to query the data stored in your smart contract, including its storage and functions.

For example, to send a transaction to a smart contract called MyContract, you can use the following command:

$ opbnb-cli send MyContract MyFunction --data "Hello, world!"

This will send a transaction to the MyContract contract, executing its MyFunction function and storing the data parameter in its storage.

Testing and debugging

Engaging in thorough testing and debugging is a pivotal phase in smart contract development, serving to pinpoint and rectify any errors or vulnerabilities within the contract.

The following tools and strategies contribute to effective testing and debugging:

Truffle Suite - is a testing framework for smart contracts, allowing you to write and run tests for your contracts.

OpBNB Scan - is a tool for scanning and analyzing smart contracts on the opBNB network, allowing you to identify any security vulnerabilities or issues.

Remix and Hardhat - are development environments for smart contracts, providing a visual interface for testing and debugging your contracts.

OpBNB Explorer - is a tool for exploring and analyzing the opBNB network, allowing you to see the details of your contract and its interactions with other contracts.

For these tools that I have shown and by utilizing these tools and strategies, for sure it will empowers users to safeguard the security, reliability, and intended functionality of their smart contracts. It also provides a proactive means to minimize vulnerabilities and ensure the robust performance of the smart contract in alignment with their objectives.

Advanced Topic: Integration with BSC

Now that we've reached the advanced topic, I will provide you with a detailed explanation of the topic “Integration with BSC” in the context of developing on opBNB.

Handling Cross-Chain Communication between opBNB and BSC

Navigating cross-chain communication between opBNB and BSC is a pivotal aspect of opBNB development. Given that BSC operates as an independent blockchain, developers must comprehend the distinct transactions, smart contracts, and security protocols inherent to BSC. This understanding is crucial for seamless integration and interoperability between the two blockchain networks.

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To establish seamless communication and interaction between opBNB and BSC, a cross-chain bridge is employed. This bridge serves as a crucial link, enabling the exchange of information, assets, and functionalities between the two blockchain networks.

The cross-chain bridge acts as an intermediary between opBNB and BSC, allowing for the seamless transfer of assets, data, and smart contracts between the two chains.

The bridge contract is deployed on both opBNB and BSC, and it handles the following functions:

Asset minting: The bridge contract holds the capability to mint new assets on either opBNB or BSC. This functionality opens avenues for the creation of tokens or other digital assets that seamlessly operate across both chains.

Asset transfer: Enabling the transfer of assets between opBNB and BSC, the bridge contract facilitates the fluid movement of funds or other digital assets between these two blockchain domains.

Smart contract interaction: The bridge contract stands as a versatile entity capable of interacting with smart contracts on both opBNB and BSC. This interaction empowers the execution of intricate decentralized applications (dApps) and smart contracts, leveraging the scalability and security features inherent in both chains.

Dissecting L2 Transactions

When diving into opBNB development, grasping the mechanics of L2 transactions is crucial. L2 transactions involve off-chain processes where transactions are bundled and subsequently verified on-chain.

These off-chain transactions boast speed and cost efficiency compared to on-chain counterparts, yet they maintain the security and integrity inherent in the underlying blockchain.

To unravel L2 transactions, a comprehensive understanding of the following aspects is imperative:

Bundling: The process involves bundling L2 transactions using a technique known as rollups. This method allows multiple transactions to be compressed into a single transaction, reducing its size and accelerating execution.

Verification: Following bundling, the bundled transactions undergo on-chain verification through cryptographic proof. This proof ensures the validity of transactions and verifies ownership of assets by the correct parties.

Settlement: Once verified, the transactions are settled on-chain, and the corresponding assets are transferred to their designated owners.

Use Cases for Layer 1 and Layer 2 Interaction

opBNB and BSC, when combined, offer a versatile toolkit to craft an extensive array of use cases, encompassing:

Decentralized finance (DeFi): In the realm of decentralized finance (DeFi), opBNB emerges as a tool to construct decentralized exchanges, lending platforms, and various other DeFi applications. Simultaneously, BSC offers the potential to create intricate smart contracts and decentralized applications (dApps) within the DeFi landscape.

Gaming: Transitioning to the gaming sector, opBNB proves valuable for building gaming platforms that demand swift and secure transactions. On the other hand, BSC steps into the picture for crafting more sophisticated gaming experiences, integrating smart contracts for enhanced functionality.

Social media: Exploring the domain of social media, opBNB can be harnessed to construct decentralized social platforms designed to resist censorship and external control. Meanwhile, BSC provides the framework for developing more intricate social media applications, leveraging the power of smart contracts.

NFTs: In the arena of non-fungible tokens (NFTs), opBNB takes center stage for constructing decentralized marketplaces dedicated to NFTs. BSC, with its advanced capabilities, steps in to facilitate the development of more intricate NFT applications infused with smart contracts.

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Having completed reading the article, I, Emil Justinne Todavia, hopes that this article serves as a comprehensive guide, providing developers with a thorough understanding of the BNB Smart Chain (BSC) and opBNB.

This guide I created encompasses various aspects, including the basics of smart contracts, programming languages, tools, setting up the development environment, and delving into advanced topics like integration with BSC and cross-chain communication.

It aims to equip developers, whether beginners or experienced, with the knowledge and tools necessary to enhance their blockchain development skills on opBNB.

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