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What is the Polygon Chain Development Kit?

The Polygon Chain Development Kit (CDK) is an advanced open-source framework designed for the rapid deployment of ZK-powered Layer 2 (L2) blockchains on Ethereum. With a strong emphasis on modularity, the CDK empowers developers to either initiate new Ethereum L2 chains or seamlessly transition existing Layer 1 (L1) chains into L2s. Every chain created through the CDK is interconnected, ensuring near-instant finality, boundless scalability, and a unified liquidity pool.

Utilizing the CDK, developers can meticulously design application-specific chains to fit their unique specifications. The CDK is designed to prioritize core business functionalities and user engagement, all while maintaining peak performance and scalability. This includes choices in the virtual machine, operational mode, data availability solutions, sequencer types, gas tokens, and more.

For example, a chain tailored for a specific application might leverage the zkEVM execution environment, adopt the "validium" mode, and implement a centralized sequencer. Regardless of these individualized choices, each chain maintains flawless interoperability with all other Polygon chains, delivering a high-performance L2 scaling solution.

The diagram below provides an overview of the key components within the CDK.

The Polygon CDK at this stage defaults to the validium

As Polygon 2.0 evolves, content will be updated and expanded to reflect new configurations. The Edge product suite is included as part of the CDK.

CDK Overview

What are Application-Specific Blockchains?

Application-specific blockchains (app-chains) are specialized blockchain networks designed for specific tasks, providing increased efficiency compared to general-purpose blockchains. By focusing on a specific application, such as supply chain management or decentralized finance, these blockchains can eliminate unnecessary features and computational overhead, thereby increasing speed and resource efficiency.

However, their specificity can also lead to a lack of versatility, adaptability, and potential fragmentation in the blockchain landscape. Thus, while beneficial, these blockchains must also consider scalability, interoperability, and future-proofing.

What are Validiums?

Validiums are solutions that process transactions off the main Ethereum network using off-chain data availability and computation. Unlike traditional rollups, Validiums don't store transaction data on the L1 network. Instead, they generate ZK proofs, which are then published as validity proofs. This approach ensures data integrity while optimizing scalability and cost.

How do L2s Built with Polygon CDK Function as App-chains?

Leveraging the power of Polygon's advanced zkEVM technology, chains developed using the Polygon CDK offer a high-performance L2 scaling solution. Developers have the flexibility to choose the validium framework, which integrates a secure data availability layer managed by a Data Availability Committee (DAC). Chains built with the CDK can function like L1 blockchains tailored to specific business logic. However, as L2 solutions, they provide the advantage of near-infinite scalability. Designed with a user-centric approach, these chains prioritize core business functions and user engagement strategies without compromising on performance and scalability. The following diagram illustrates the high-level architecture of a chain developed using the Polygon CDK.


What do you Mean by Data Availability Layer?

In the realm of blockchain, data availability ensures that all nodes can access and verify the complete transaction history, which is crucial for maintaining the network's transparency, security, and integrity.

However, storing all transaction data on the main chain (L1) can lead to high costs and compromise privacy. Data availability layers tackle these issues by separating transaction execution from data storage. This allows for transaction data to be stored off-chain, reducing costs and enhancing privacy, while still being accessible for validation.

This separation introduces new challenges, such as ensuring the secure and reliable management of off-chain data. Features like the DAC within the Polygon CDK framework address these concerns, offering trusted oversight of off-chain data.

The diagram below provides a high-level overview of the Polygon CDK Validium's approach to blockchain infrastructure.


What are DACs?

Data Availability Committees (DACs) are a crucial element in many blockchain protocols, tasked with ensuring the reliability and accessibility of off-chain data. In essence, they verify the availability of data associated with specific blockchain blocks.

In the context of L2 solutions, DACs play a pivotal role in enhancing scalability. They aid in transferring significant computational work and data storage off-chain, thereby alleviating the burden on the main L1 blockchain.

The DAC is an integral element in the validium framework of the CDK, functioning as a secure consortium of nodes to maintain the accessibility and security of off-chain data. For an overview of how the DAC functions within the CDK, please explore the DAC guide, available here.

For a more detailed understanding of data availability, the Ethereum Foundation's guide on Data Availability is a great resource, accessible here.

Why Choose Polygon CDK?

Polygon CDK, integral to Polygon 2.0, reshapes blockchain infrastructure. It ensures unparalleled liquidity, optimizes performance, and facilitates seamless asset transfers, all while prioritizing user experience and data security.

Design Principles

  1. High Modularity: Polygon CDK offers a modular environment for ZK-powered L2 chain design. Developers can customize chains according to their needs, from choosing the execution environment to determining the gas token.

  2. Hyper-Scalability: CDK-developed L2 chains enhance transaction speed and can be multiplied to achieve Polygon 2.0's vision of a highly scalable ecosystem.

  3. Unified Liquidity: Ensuring fluid asset transfers across multiple chains within Polygon 2.0's L2 ecosystem, CDK-developed chains champion unified liquidity, fostering a vibrant, efficient digital economy.

  4. Independent Data Availability: With a dedicated data availability layer and a DAC, CDK-developed chains provide robust off-chain data access and reliability. This structure, independent of Ethereum, ensures substantial data resilience and integrity.

  5. Composable Interoperability: Thanks to the LXLY Bridge, CDK-developed chains enhance seamless interaction and asset exchange across diverse blockchains. This interoperable infrastructure cultivates an interconnected and versatile ecosystem, promoting cross-chain collaboration and interaction.

  6. Near-Instant Finality: Chains deployed using the Polygon CDK rely on cryptographic security, ensuring transaction integrity without the need for full nodes. This approach guarantees near-instant finality and robust security.

The following diagram illustrates how CDK-developed chains fit into the overall Polygon 2.0 ecosystem.


Key Factors for Adoption

  1. Scalability for Ethereum: CDK-developed chains significantly scale Ethereum. They allow projects and businesses to build applications to meet their block space needs while preserving the security and integrity of the Ethereum mainnet.

  2. Business Logic Customization: CDK-developed chains fully support the Ethereum Virtual Machine (EVM), which allows for custom gas limits, opcode compatibility, and technology integrations. This enhances flexibility in business logic design and scalability through Polygon zkEVM.

  3. Privacy Options: CDK-developed chains enable the creation of private app chains, providing an option for those who prioritize privacy in their applications. This feature supports clients in maintaining the confidentiality of their application data while still enjoying the benefits of blockchain technology.

  4. Compliance-Oriented: CDK-developed chains enable network sovereignty and regulatory compliance. They allow network maintainers to choose administrators who comply with local regulations, ensuring conformity to regional regulatory requirements.

  5. Extensive Web3 Support: CDK-developed chains, being direct forks of the zkEVM stack, facilitate easy porting of services. They also leverage a comprehensive ecosystem with premium service providers offering essential tools for application integration, development, and deployment.

How to Get Started

The CDK Validium is actively being developed, with ongoing feature enhancements and issue resolutions. We recommend starting with the Quickstart guide to gain a quick hands-on introduction to CDK Validium.

Meanwhile, the Polygon Labs team remains at your disposal. We encourage you to connect with the team for further engagement with the CDK Program.

Flexibility and Considerations

The CDK Program uses the validium implementation for app-chains, targeting use cases highly reliant on robust data availability and cost-effectiveness.

However, the framework's design flexibility enables future expansion to support rollup-based app-chains, as per evolving use case requirements.