ZetaChain’s mission is to serve as a platform for universal access, simplicity, and utility across any blockchain. Today we’re excited to introduce Gateway and Localnet, which greatly improve DevX for Universal Apps — single smart contracts on ZetaChain’s EVM that are natively connected to any other blockchain. Gateway plays a significant role in the active ZetaChain 2.0 upgrades.

Key Takeaways

• Apps on the Universal EVM (Universal Apps) can both natively access and be accessed from any connected chain without requiring users to switch networks. They use the ZRC-20 token standard to permissionlessly withdraw tokens to connected chains as native assets.
• The hub-and-spoke model offered by Universal Apps lets you manage native foreign assets and data from a single place. Rather, point-to-point messaging between contracts on different chains is complex, difficult to scale, and cannot extend to non-smart chains such as Bitcoin.
• The complete smart contract interface revamp with Gateway enables externally-owned accounts (EOAs) and apps on connected chains to efficiently call Universal Apps, send tokens, and handle gas queries through a unified API.
• Gateway unlocks complex multi-step operations e.g. send BTC from Bitcoin to Universal App on ZetaChain, lock in a vault, provision USDC, then swap USDC for another token on Ethereum — in one click.
• The new localnet environment enables rapid contract deployment and interaction with almost instant transaction finalization and feedback as if operating on a single chain

Universal Apps

A Universal App is a smart contract on ZetaChain’s EVM that is natively connected to any other blockchains (Bitcoin, EVM, non-EVM, heterogeneous L2s, Etc.).

Unlike a regular contract, a Universal App can accept contract calls, messages and token transfers from any connected chain. It can also trigger contract calls, and make token transfers on connected chains. These abilities enable Universal Apps to orchestrate complex multi-step transactions that span across chains.

For example, a Bitcoin user can interact with a Universal App to send USDC to a recipient on Ethereum. An Ethereum user can buy an NFT on ZetaChain and send it to their account on the BNB chain — all in one step.

Universal Apps are deployed on ZetaChain's Universal EVM, which extends the EVM with omnichain interoperability features. This means your existing contracts will work out of the box on ZetaChain, and with some modifications, they can gain powerful omnichain capabilities.

Challenges of point-to-point Messaging

In a point-to-point messaging system, a contract on one chain communicates directly with another contract on another blockchain. This setup is straightforward and effective for a small number of interconnected blockchains, offering a simple and easy way to establish communication channels.

However, as the number of blockchains and contracts grow, the complexity increases exponentially. Each contract must establish and maintain a direct link with every other contract, resulting in a dense web of connections. This architecture can lead to several issues:

• Scalability challenges: As the number of nodes increases, the number of potential connections grows quadratically. Managing these connections can become cumbersome and resource-intensive.
• Maintenance and upgrades: Updating or maintaining a point-to-point system can be difficult, as changes need to be implemented across numerous connections simultaneously.

Despite these challenges, point-to-point systems were useful for small scale cross-chain applications that did not need access to shared state.

Introducing hub-and-spoke with Universal Apps