A Brief Discussion on Polygon: The "Internet" of Ethereum-Compatible Chains

Source: Bankless DAO

Compiled by: Bitpush Exclusive Chen Zou

The Polygon chain was originally launched as a layer-1 network under the name Matic. At its launch, Matic aimed to become an "Internet of Blockchains," allowing developers to build products with cross-chain compatibility and interoperability. However, as Ethereum became the dominant smart contract chain, Polygon gradually faded from the spotlight. But with the development of the entire network and the saturation of Ethereum, the market began to slowly realize the importance of cross-chain solutions. In response, the Polygon team shifted to becoming a framework for building and connecting Ethereum-compatible blockchains to help Ethereum scale, changing their goal from "Internet of Blockchains" to "Internet of Ethereum-Compatible Chains."

Polygon has always focused on the experience of its users and developers. Since rebranding, developers have begun to flock to Polygon, and the slogan "built for developers" has seemingly become a reality. Due to Polygon's optimization of the developer experience and its dual halo of alleviating Ethereum's scalability issues, Polygon made significant progress in 2021.

In the past six months, the number of contracts deployed on Polygon has completely surpassed that on Ethereum.

Since May 2021, the number of daily active addresses has begun to rise sharply.

To continue its growth, Polygon must attract new developers while retaining them. To engage developers (and ultimately users) in building its ecosystem, the Polygon team has focused on creating a lightweight deployment development environment for blockchain networks, while also emphasizing the enhancement of its modular security (referred to as "security as a service").

Disadvantages of Ethereum; Breakthrough Points of Polygon

As Ethereum became the dominant blockchain, while enjoying an increasingly prosperous ecosystem, gas fees became an indelible pain for countless users. Polygon's strategic focus on the Ethereum ecosystem now appears to be prescient. In the first half of 2021, gas fees consistently exceeded 100 gwei, peaking at over 350 gwei.

Due to the price volatility of Ethereum and the complexity of network interactions, a single transaction could cost users tens or hundreds of dollars, while transaction processing times would also increase significantly. These issues have forced users and developers to seek suitable alternatives.

Polygon aims to address the dual issues of transaction costs and time costs by providing various scaling solutions, while retaining users for Ethereum. Polygon is highly aligned with Ethereum in its goals and philosophy, maintaining Ethereum's security as a final shield through EVM compatibility.

Polygon Framework: Overview

Independent Chains and Secure Chains

There are two types of blockchains that can be deployed on Polygon: independent chains and secure chains.

"Independent" chains are blockchains that do not rely on Ethereum's consensus for security. This solution is aimed at projects that already have their own validating nodes or are seeking to implement another scalability solution. These independent chains are typically used by enterprise networks or mature chains looking to integrate with the Polygon-Ethereum ecosystem.

"Secure" chains refer to chains that do not have their own validating network but rely on Polygon's security layer. Polygon offers a high level of security while allowing developers to choose from various security solutions, with the most popular being the Polygon PoS (Proof-of-Stake) chain. These secure chains are designed to assist startups and projects that require a reliable security system.

Whether independent or secure, deploying on Polygon is relatively straightforward for developers. This ease of deployment provides developers with more options to meet their users' needs, and this flexibility comes from Polygon's infrastructure.

Architecture

Regardless of whether they are independent or secure chains, blockchains deployed on Polygon operate within the same architectural framework. Polygon's architecture consists of four components: Ethereum Layer, Security Layer, Polygon Network Layer, and Execution Layer.

Ethereum Layer

Polygon uses Ethereum as its foundational layer. This layer consists of a set of smart contracts on Ethereum that settle transactions through validating nodes, staking nodes, and relaying information between the Polygon and Ethereum ecosystems. This layer is responsible for resolving the final processing flow on Ethereum. While this layer is optional, it is a significant advantage of the architecture. By leveraging Ethereum as the endpoint, Polygon can effectively utilize Ethereum's security as a final shield and benefit from it.

Security Layer

The second architectural layer is an optional security layer. This layer is referred to as "Validation as a Service," as it allows developers to utilize several security solutions to validate transactions. Users can adopt fraud proofs or PoS sidechains (among other solutions) to ensure security.

So far, the most popular security solution is the PoS sidechain. The PoS sidechain utilizes a set of approximately 100 validating nodes to ensure the security of blockchain projects (which incurs a certain validation fee) and manages the validating nodes. Additionally, this layer can utilize Ethereum miners (the ultimate validating nodes) to reach consensus.

Similarly, this layer is optional. Generally speaking, structures that are further away from Layer 1 tend to lack in security but improve transaction throughput and user experience. Not all chains need to utilize Polygon's security layer. Some projects, such as blockchain games, may even wish to reduce security in exchange for faster settlement speeds, thereby providing players with a better user experience.

Polygon Network Layer

The Polygon Network Layer is a network composed of independent blockchains that is responsible for determining transactions, producing blocks, and deciding the consensus of each chain. These chains can be either independent chains or secure chains. The block producers of these chains group their respective transactions, and based on the security solution, the network layer publishes a Merkle root as a checkpoint for Layer 1.

Execution Layer

Finally, there is the Execution Layer. The Execution Layer interprets and executes the transactions determined by the Polygon Network Layer. This layer has two components.

Execution Environment -- Implemented by a virtual machine. Similar to EVM, it can track the state of the blockchain.

Execution Logic -- Implements state transitions for specific Polygon blockchains. This logic is used to define the transition to the next blockchain state, and Ethereum can be thought of as an "infinite state machine" (as opposed to a finite state machine, which is a mathematical model representing a finite number of states and the transitions and actions between those states).

However, among all these layers, the key value-added point for developers is the security layer, as it allows the flexibility of the Polygon framework to truly shine. Developers can choose the security solution that best fits their project, and if they choose to change direction, they can swap solutions. The goal is to provide developers with a set of tools to customize their blockchain projects.

Security Layer: In-Depth Exploration

While low transaction costs and high processing efficiency are the main drivers of Polygon's rapid development, this growth would not be possible without Polygon's modular security solutions. These "security as a service" solutions include Polygon's PoS sidechain and fraud proof mechanisms, while new solutions like the universal data availability layer Avail and Hermez ZK-rollups are still under development. Some of these solutions can be used in combination, but they all rely on the Polygon SDK.

Polygon SDK

The Polygon SDK (Software Development Kit) is a framework for projects to launch their own EVM-compatible chains. This SDK implements "security as a service," allowing developers to choose the ideal scaling solution for their projects.

As shown in the image above, the Polygon framework separates functionalities, allowing developers to choose their own consensus mechanism or develop their own consensus mechanism while maintaining interoperability with other chains within the Polygon ecosystem.

This interoperability allows Polygon chains with different scaling solutions to communicate with each other, enabling developers to choose customized security solutions. Polygon also plans to add more out-of-the-box consensus mechanisms, database implementations, and other auxiliary services.

Polygon Hermez (ZK-rollup) Security

Polygon recently acquired Hermez, a ZK-rollup solution. Hermez is developing a ZK-rollup equivalent to EVM, which is a very promising layer-2 solution designed to make asset transfers more secure while reducing costs. ZK-rollup compresses batches of transactions into a small amount of validity proof (or zk-SNARK) data. This data is then published on-chain for the verification of the proof's correctness. Compared to Ethereum, Hermez boasts 133 times the throughput, with transaction costs only one-tenth.

This solution avoids the drawbacks of plasma, such as the seven-day withdrawal wait time, as there is no need to challenge the data through fraud proofs, since SNARK proofs are computationally easy to verify. However, the structure of validity proofs remains computationally intensive. The truly anticipated solutions that users are looking for will still take some time, and like Avail, the future of ZK-rollup also looks promising.

Polygon Miden

Polygon has also recently announced a new ZK project called Miden, which is a STARK-based, EVM-compatible rollup. The project is led by Bobbin Threadbare, a core developer of other ZK technologies such as Distaff VM (a STARK-based virtual machine) and Winterfell (a high-performance STARK verifier).

This solution will be purely based on STARK, supporting arbitrary transactions and automatically generating execution proofs. Miden will compile Solidity code into Miden Assembly, which the Miden VM will use to execute transactions and generate zero-knowledge proofs.

Hermez aims for complete compatibility with EVM (at the code level), while Miden will start with Solidity compilation and then transition to other languages.

Conclusion

It has proven that Polygon's focus on providing scaling solutions for Ethereum has been successful, as the Polygon network experienced explosive growth throughout 2021. To continue this growth, Polygon is working to establish out-of-the-box scaling and security solutions that enable developers to leverage Polygon's reduced transaction costs and inclusive times. With over $1 billion in funding for ZK-rollup solutions alone, Polygon has ample resources to further expand its solution suite to help Ethereum scale and meet the anticipated network load in the future.