Introduction to Appchains (App-specific Blockchains)
Appchains, short for application-specific blockchains, are decentralized ledgers designed exclusively for a single decentralized application (dapp). This approach grants developers greater flexibility in shaping ecosystems, governance structures, and consensus algorithms tailored to their decentralized applications.
How Appchains Operate
Appchains function similarly to the base blockchain but operate on top of it. The key distinction is their application-specific nature. In terms of security, appchains rely on first-layer blockchains (L1), ensuring customization and significant performance potential. These systems typically involve a utility token for staking, internal application transactions, and voting. Validator support from the main network sustains appchain operations if they allocate resources to a specific application.
Advantages of Appchains
Deploying appchains offers several advantages compared to L1, second-layer solutions (L2), and sidechains. Appchains introduce customization and increased system performance without sacrificing security, as they build upon the foundation of the base blockchain. Unlike L1, appchains avoid competition for limited computational resources, mitigating potential performance degradation and lengthy platform update processes.As decentralized applications gain popularity, appchains can provide low and predictable transaction costs, positively impacting user experience.
Developers might face the need for extended customization and optimization as dapps evolve, addressing parameters such as throughput, finality, security levels, and accessibility (permissionless or permissioned).For traditional organizations, appchains offer a gradual transition into Web3 without immediately making platforms public. Initial requirements, like validator KYC compliance and relying on a limited group of developers, allow companies to choose specific services for cross-chain interactions.
Challenges of Appchains
The primary distinction and potential limitation of appchains lie in their application-specific focus. Unlike L2 solutions, which can interact with various dapps, appchains imply limited composability and some degree of isolation, risking liquidity fragmentation. Integrating cross-chain bridges can address this issue, but they often become targets for hackers.If an application sees limited activity, launching and maintaining an appchain may prove futile. Validators allocated to the platform could utilize resources more effectively elsewhere. Operating an appchain may entail challenges related to managing additional infrastructure elements like sequencers or validators.
Developers may lack ready-made solutions for block explorers, RPC providers, indexers, oracles, fiat gateways, etc.Creating L1 solutions has its advantages, such as access to abundant resources, infrastructure elements, and developer tools, especially for newcomers. This abundance simplifies integration with diverse ecosystems.L2 allows developers to enhance service scalability without significant codebase changes. These solutions ensure high security levels by relying on the underlying blockchain. For example, Optimism and Arbitrum process transactions quickly and submit fraud proofs to the main network using Optimistic rollups technology.
Distinguishing Appchains from Sidechains
Sidechains involve a parallel network with a two-way connection to the main blockchain, but they do not rely on L1 security. Unlike L2, sidechains do not send transactions to the main blockchain.Appchains are crafted for specific applications, while sidechains perform various operations. The main drawback of sidechains lies in reduced security due to limited decentralization.A well-known sidechain is Polygon Proof of Stake within the Polygon project ecosystem. This project also includes Polygon Edge, an open-source development environment for creating L2 solutions.
Projects Embracing Appchains
Some blockchain projects empower developers to create appchains. Among them:
Polkadot Parachains
Cosmos Zones
Avalanche Subnets
Polygon Supernets
Polkadot Parachains: Tailored Solutions for Specific Applications
Polkadot’s EVM-Compatible Parachains
Polkadot operates as a network of EVM-compatible blockchains known as parachains, interconnected through the Relay Chain. The Relay Chain specializes in validating transactions for all associated systems.The Proof-of-Stake consensus mechanism is engaged in the Relay Chain, where validators stake DOT (Polkadot’s native token). Each validator group is responsible for a specific parachain, assigned and maintained by collators. Collators gather user transactions and confirm blocks based on the Proof-of-Validity algorithm, receiving rewards for their work as node collators.The number of slots for parachains in the Polkadot network is limited to 100 and is allocated through auctions. DOT holders vote for projects to connect to the Relay Chain in subsequent auctions.Parachains can also serve as bridges, connecting the Polkadot network to external L1 blockchains like Ethereum. Developers utilizing parachains enjoy the benefits described earlier, including economic and managerial structure flexibility and the use of utility tokens.One major drawback of parachains is the limited number of slots available, making such solutions less accessible. The Polkadot team is actively working on parathreads—parachains with pay-as-you-go models—to address this limitation. Developers can load their project code into the Relay Chain and launch multiple collators without waiting for parachain auctions.The number of supported Polkadot parathreads is also limited to 10,000. However, a notable limitation is the lack of smart contract support on the Relay Chain, restricting the capabilities of the Polkadot network.
Examples of Parachain Projects:
Acala: A DeFi hub for the Polkadot network.
Litentry: A cross-chain aggregator for identity solutions.
Cosmos Zones, Avalanche Subnets, and Polygon Supernets
Cosmos Zones:Cosmos Zones operate within the Cosmos ecosystem, providing interoperability between blockchains. Each zone is an independent blockchain with its validators and governance, enabling developers to create custom blockchains.
Avalanche Subnets:Avalanche, known for its high-throughput consensus protocol, features subnets that allow developers to customize their blockchain’s consensus mechanism and interoperability features. Avalanche’s architecture supports multiple virtual machines, providing flexibility for developers.
Polygon Supernets:Polygon Supernets represent a scaling solution within the Polygon ecosystem. They introduce modular components to enhance scalability, allowing developers to choose specific functionalities for their decentralized applications.
Diverse Paths in the Appchain Landscape
The growing adoption of appchains indicates a shift towards more tailored and scalable blockchain solutions. As projects like Polkadot, Cosmos, Avalanche, and Polygon continue to innovate, developers are presented with diverse options to match their specific application needs. The evolving appchain landscape promises increased customization, scalability, and interoperability, ushering in a new era for decentralized applications.