The technology and significance of Appchain: Everyone can have their own customized blockchain

PANews · 2023-02-09T06:05:02.000Z
Original text: "The Appchain Galaxy: Where Everyone Gets a Blockchain" by 0xFishylosopher, Web3.com Ventures Compiler: Wang Eryu, PANews introduction Ethereum is great, at least most people are happy with it. But Ethereum and other public chains have a key problem, which is a lack of customizability. Sure, you can write and deploy smart contracts, but a single user or company cannot truly transform its consensus mechanism, execution engine, and other underlying architecture. After all, there are too many people using Ethereum, and the rules cannot be changed if you want. If you are building a cross-chain decentralized exchange and need to aggregate data from different chains, or want to create an on-chain real-time strategy game, or you are a Fortune 500 company that wants to track the supply chain, existing public chains are They can't handle your needs, they can't handle the processing volume, data aggregation, or privacy requirements these applications require. Therefore, the concept of "appchain" came into being. Application Chain is a decentralized blockchain network dedicated to applications, dedicated to supporting specific use cases and meeting specific needs. This article will introduce three ways to enter the emerging application chain field through examples: Cosmos ecosystem, Hyperledger Fabric and Rollups-as-a-Service (RaaS), and discuss the impact of the rise of application chain on the entire Web3 infrastructure field.
原文：《The Appchain Galaxy: Where Everyone Gets a Blockchain》by 0xFishylosopher，Web3.com Ventures
Compiled by: Wang Eryu, PANews
Introduction
Ethereum is great, at least most people are happy with it. But there is a key problem with Ethereum and other public chains, which is the lack of customizability. Of course, you can write and deploy smart contracts, but a single user or company cannot really transform its consensus mechanism, execution engine and other underlying architecture. After all, there are too many people using Ethereum, and the rules cannot be changed just because you want to.
If you are building a cross-chain decentralized exchange, need to aggregate data from different chains, want to build an on-chain real-time strategy game, or are a Fortune 500 company that wants to track the supply chain, existing public chains cannot meet your needs. They cannot cope with the processing volume, data aggregation, or privacy requirements required by these applications. Therefore, the concept of "appchain" came into being. Appchain is a decentralized blockchain network specifically for applications, dedicated to supporting specific use cases and meeting specific needs. This article will introduce three ways to enter the emerging appchain field through examples: Cosmos ecosystem, Hyperledger Fabric, and Rollups-as-a-Service (RaaS), and discuss the impact of the rise of appchain on the entire Web3 infrastructure field.
Cosmos Network
The Cosmos Network is probably one of the most important application chain solutions for Web3. As early as 2016, Cosmos was committed to creating a "blockchain internet", the infrastructure of a multi-chain world. Cosmos basically provides a set of software development kits (SDKs) that bring developers the tools and interfaces they need to easily build their own blockchain applications. The SDK includes some out-of-the-box default architectures, such as the Tendermint PoS consensus protocol, but developers have a lot of room to rewrite these default architectures and design blockchains with custom consensus mechanisms, token standards, and smart contract platforms.
The “Hubs and Zones” Model of the Cosmos Network
There are two types of blockchains in the Cosmos network: "hubs" and "zones". "Zones" are easy to understand, that is, application-specific chains that run applications themselves (such as decentralized exchanges or on-chain games). "Hubs" connect these "zones" with other "hubs" to enable inter-chain communication through the "Inter-Blockchain Communication Protocol" (IBC).
At the center of the Cosmos network is the "Cosmos Hub," the first "hub" chain built on the Cosmos network, which essentially acts as the "central station" for all other hubs and zones. But as shown in the diagram above, a "hub" doesn't necessarily have to be connected to the Cosmos Hub. For example, a private company could launch its own private hub chain, connecting its own private zone chain.
Cosmos SDK places special emphasis on customizability and interoperability, and developers have a lot of room to play freely. There are some important general L1 chains within the Cosmos ecosystem, such as the EVM-compatible BNB Chain (formerly Binance Smart Chain). The interoperability of the Cosmos network is of great help to application chain builders, allowing application chains to access data from a large number of blockchains through IBC. Therefore, many application chains built using the Cosmos network require services such as oracles and multi-chain DEXs that aggregate data from many different chains.
 Hyperledger Fabric
Hyperledger Fabric is another way to deploy application chains. It is an open source blockchain platform for building enterprise-level applications and solutions. It is a Hyperledger project hosted by the Linux Foundation.
Like Cosmos SDK, Hyperledger Fabric is also committed to supporting modular blockchain network architecture, providing flexibility for building and deploying blockchain-based applications. It provides a plug-and-play architecture that makes it easy to add or replace components such as consensus, membership services, and smart contract execution (chain code). But there is a key difference between Cosmos SDK and Hyperledger Fabric, that is, the audience they are targeting is different: Cosmos SDK is aimed at Web3 native users and developers, while Hyperledger Fabric is aimed at enterprise-level institutional customers. Therefore, Cosmos SDK focuses on building decentralized, interoperable systems, while Hyperledger Fabric focuses on building private and permissioned networks, and explicit authorization must be obtained to join and participate in the network.
Indeed, enterprise application chains operate in a very different way than Web3 native application chains. While the latter are usually focused on token economics and the use of blockchain structures to achieve product financialization, the former are focused on using blockchain to improve the efficiency of recording and maintaining data. Enterprise application chains basically just take advantage of the characteristics of blockchain: tamper-proof, verifiable, append-only data structures, and data writers can span different time and geographical locations. In essence, the purpose of application chains based on Hyperledger Fabric is just to replace the outdated and inefficient databases that enterprises have maintained for decades.
As shown in the figure above, all the "permissioned nodes" on the Hyperledger Fabric blockchain are basically employees from various parts of the supply chain, who use blockchain to synchronize records of different data states, such as a product has entered a factory or a store. They rarely pay attention to the interconnection of different blockchains, and unlike Cosmos, Hyperledger Fabric does not provide native support for inter-chain connections, but is equipped with data APIs and interfaces for integration with other blockchain networks or systems. This means that inter-chain communication solutions can be built using Hyperledger Fabric, but custom development and integration are required, which is different from the hub and regional design built into the Cosmos ecosystem. This approach is also logical: as an enterprise-level application chain, blockchains built using Hyperledger Fabric are usually shielded from the outside world and do not want the public to disrupt supply chain data.
Hyperledger Fabric has been used to manage Walmart's supply chain. Walmart's AppChain, also known as the "Walmart Food Traceability Platform", is a blockchain-based food traceability system designed to improve food safety and transparency in the supply chain. Walmart's AppChain tracks and traces the entire process of food from farm to shelf, helping to quickly identify and resolve any potential food safety issues. At each stage of the process, suppliers must upload labels and authenticity certificates to the blockchain through a web interface, and this information will be permanently available to all stakeholders. As a result, blockchain, as a single source of information, can greatly reduce the time it takes to record and track food quality issues (such as foodborne illnesses):
The food traceability system built on the Hyperledger Fabric blockchain for both products has shown remarkable results. For Chinese pork, uploading the authenticity certificate to the blockchain has greatly improved the once problematic system. For American mangoes, the time required to trace the source has been reduced from 7 days to... 2.2 seconds!
Hyperledger Foundation
In summary, Hyperledger demonstrates a very different use case for Lisk than Cosmos: an enterprise use case, where blockchain is used as an alternative to traditional methods of recording and tracking data. Of course, some would argue that this use case is “not true Web3” because it does not leverage token economics, decentralization, and crypto-native principles in the same way. But enterprise adoption of Lisk cannot be ignored, the underlying technology is the same, and it is an important step in increasing public trust in blockchain technology to achieve mass adoption. In the long run, the integration of Lisk by companies like Walmart is expected to greatly promote the integration of Lisk in the “Web3 native” world.
 Rollups-as-a-Service
A newer way to build application chains is to use rollups, specifically "rollups-as-a-service" (rollups as a service/RaaS). Rollups-as-a-service is a blockchain extension solution that performs computation and storage off-chain while maintaining the security and trust level of the underlying blockchain. It works by compressing a large number of transactions into a single transaction, which is then recorded on the underlying L1 public chain (usually Ethereum).
Application chains can take advantage of rollups because they provide a way for dApps on application chains to scale transaction processing and storage without sacrificing the security and trust level of the underlying blockchain. Although developers lose some flexibility in customizing the underlying consensus layer compared to Cosmos-based solutions, there are several advantages to using rollups-as-a-service for application chains rather than full chains.
Perhaps the most important advantage is that developers do not need to build their own validator set. By outsourcing consensus and settlement to the underlying L1 public chain, the application chain solution is not only cheaper but also more robust, and the underlying L1 guarantees its security. In addition, rollups are modular vertical solutions that are not limited to a single blockchain framework and can utilize data and functions on multiple blockchains.
In the rollup application chain model, the L1 chain is actually equivalent to a secure "hub" containing massive amounts of data. For example, a game application chain can adopt a rollup-based solution and utilize Ethereum's security capabilities at the consensus and settlement level, and Solana's high processing power at the execution speed level.
Rollups-as-a-service companies provide application chain developers with the infrastructure and services needed to deploy customized application chain rollup solutions. Different RaaSs simplify toolkits to different levels: projects such as Op Stack are built on SDKs, allowing developers to customize rollups more extensively; projects such as Constellation focus on completely code-free "white glove" deployment solutions, allowing application chain developers to focus on the "application" level of development rather than the "chain" level.
The significance of application chain
The rise of the above-mentioned application chain solutions has a profound impact on the entire Web3 infrastructure landscape. Application chains have brought about a paradigm shift in the relationship between "chain" and "application": from a supply-side driven model to a demand-side driven model.
When infrastructure solutions are not yet mature and many modern infrastructure concepts (PoS, sharding, and rollup) are still in the proof-of-concept stage, the purpose of infrastructure projects is often to explore the feasibility of technical solutions. "Third-generation blockchains" such as Avalanche, Cardano, NEAR, and Solana are the most typical. The supply (processing volume and technical implementation) of these blockchains drives the demand for them. In other words, the design of the "chain" determines the design of the "application".
However, the rise of application chains clearly marks the arrival of the fourth generation of blockchain: the demand for blockchain will drive the supply of blockchain. The technical routes mentioned above, Cosmos Network, Hyperledger Fabric and Rollups-as-a-Service, are all plug-and-play blockchain deployment solutions that are simple, customizable and cost-effective. It has never been easier to design, customize and deploy your own blockchain. Therefore, the situation is reversing: the design of the "application" will determine the design of the "chain".
One result that this is expected to bring is that the L1 scenario will become more centralized, from a monopolistic competition scenario (slightly different between different L1s) to an oligopolistic scenario, where a few key blockchains with large ecosystems and liquidity will dominate the entire industry. Because with the emergence of application chains, head DApps will no longer need to be deployed on small L1s. They can run their own blockchains (with unlimited customization capabilities) or deploy application chain rollups on mature large L1s. In terms of flexibility, customization, security, and support, small L1s are simply unable to compete with the combination of large L1s + application chains.
In addition, application chains are also a key mechanism for attracting institutions to join Web3. As mentioned earlier, while enterprise chains such as Hyperledger are usually excluded from the typical Web3 concept, they use the same underlying blockchain technology to improve transparency in logistics and supply management. So why not also expand to payments and other areas? I believe it is only a matter of time before these enterprise-level blockchains further integrate DeFi, payment and NFT projects native to Web3. There are already some projects exploring the expansion of Cosmos IBC beyond the Cosmos application chain to connect platforms such as Hyperledger Fabric and lock in other enterprise-level blockchain solutions.
 in conclusion
Today, we can confirm that there has never been and will never be a one-size-fits-all blockchain. Whether through Cosmos SDK, Hyperledger Fabric or Rollups-as-a-Service, as custom application chains mature and the deployment threshold is lowered, the experience in the field of Web3 infrastructure will eventually shift to application-first and user-first, which is also a sign of Web3's maturity. The future of Web3 is a multi-chain galaxy, and given the customizability, efficiency and easy deployment of application chains, it will play an increasingly important role and shine in the decentralized galaxy.