Bitcoin today is essentially a single-chain system. However, with the rapid increase in the number of blockchain users and transactions, the problems faced by the single-chain system have become increasingly prominent:
1. The network-wide consensus efficiency of a single chain is limited by the scale of consensus nodes
The ever-increasing transaction and data block information makes the blockchain increasingly bloated, and the parallel ability of block generation is insufficient. The existing Ethereum EVM and others need to execute and process transactions in sequence. At the same time, for security and decentralization considerations, each full node will execute each transaction and store the entire state tree. There are some technologies to solve the problem of transaction scalability, such as
Bitcoin-NG, Lightning Network, Raiden Network, but did not solve the state scalability problem. We hope to be able to process more than 10,000 transactions per second without forcing each node to become a supercomputer or forcing each node to store more state data, which requires a comprehensive solution. The sharding technology is an effective attempt to solve the single-chain problem. A solution has been proposed, but it may take 2 to 5 years to fully expand using the sharding technology.
2. The single-chain network-wide backup mechanism reduces storage efficiency
The core limitation of public chains is that every transaction must be processed by every node in the network.
Every operation performed on the public chain blockchain must be processed by every node in the network. The design of the blockchain is like this, which is the part that makes the public chain authoritative. A node does not need to rely on other nodes to tell it what the current state of the blockchain is, it will figure it out by itself. This puts a fundamental limitation on transaction throughput: it cannot be higher than the transaction throughput we require for a single node. Take the most typical Cryptokitties application as an example, which is enough for serious network congestion. Since many active users request multiple transactions every day, this places a heavy burden on the public chain network. Many transactions that previously took a few seconds will be delayed to 10 minutes or fail completely.
3. The single chain system cannot meet the diverse demands of the business
It is impractical to move the entire real society to a blockchain. The real society itself creates value by industry and economic fields. Each field maintains its own independent value economic system, and the single-chain system cannot satisfy value. The actual demand for system diversity. Therefore, a single chain cannot meet the differentiated demands of various businesses or industries for the characteristics of blockchain technology. For example, some businesses focus on real-time requirements, and some businesses focus on reliability requirements.
To solve the above problems, there are three seemingly "simple solutions." The first simple solution is to abandon the expansion of a single blockchain, and users can use many different similar blockchains to achieve the purpose of increasing throughput, but the security is reduced. The second solution is to increase the block size, which is familiar to everyone. The main problem is to increase the processing pressure of user nodes, which causes many individual users to give up verification, which may pose a greater risk of centralization. The third solution is joint mining. In this method, users can have many chains, but these chains share the same mining resources and capabilities, which actually increases the pressure on miners.
AI proposes a multi-layer polymorphic main chain-sub-chain multi-chain system, which, as the name suggests, allows each business to run on their own "tracks" more efficiently, and at the same time will not cause operating errors or even systems due to "track bifurcation" collapse. Sub-chain synchronization does not simply split one chain into multiple, but takes into account factors such as storage efficiency, throughput, and business differences to create differentiated sub-chains for different businesses, and rely on the main chain for higher-level Consensus verification, without reducing security, improves the processing performance of the blockchain and meets the diverse demands of the business.
The multi-chain system is generally divided into a two-layer structure of the main chain and the sub-chain, and the transaction processing, state storage, transaction download and broadcasting of different businesses are dispersed across sub-chains and nodes. The multi-chain system includes two types of chains, one is the main chain, and there is only one main chain, which is responsible for the selection of sub-chain verification nodes, the selection of sub-chain block sponsors, the storage of the final state of the sub-chain, and the punishment of malicious behavior; the other is Sub-chains can have multiple sub-chains, and different sub-chains can be built according to different business characteristics. The underlying technology of the main chain and the sub-chain are interoperable, and they can share the same blockchain architecture, account tree structure, and consensus algorithm system. However, in the specific implementation process, the technology can be selected according to the special effects of the sub-chain.