What is unique about boca's parallel chain?

Original title: "What is unique about boca's 'Parallel Chain'?"

Source: PolkaWorld  & have spent

Polkadot is a blockchain for scalable decentralized computing and interoperability. In this article, we'll look at one of the main parts of a network: parallel chains.

Today's blockchain takes a very standard form and consists of two parts. The first part is the consensus algorithm, which provides security. The second part is the state machine, which provides some aspect of the chain through which the chain obtains security. Ethereum, Bitcoin, Zcash, and the like are all protected by workload Proof Consensus (PoW) or variants of it, but the types of transactions and accounts they process (the things that make up their unique state machines) are completely different. Imagine a developer with a great idea for a new blockchain that could provide effective privacy or wealth distribution or other exciting features. As developers work to implement this unique state machine, they must also implement some kind of consensus algorithm, and it must compete with others for security resources when it starts its chain. This brings some overhead and insecurity to the development of new blockchain projects.

Let me introduce you to parallel chains. Parallel chains (parallel-running chains) are a simple form of blockchain that attaches to the security provided by the "trunk chain" rather than providing its own security. It is called a relay chain because it not only provides security for the parallel chains that are connected, but also guarantees secure messaging between them. A key feature of parallel chains is that they perform computations that are essentially independent. Turing's comprehensive universal system of intelligent contracts had problems determining which transactions would "conflict" with each other, meaning that potentially parallel transactions often ran in sequence, wasting valuable computing time. Drawing boundaries between parallel chains means that we can execute all of them at once without fear of conflictIf we have 10 parallel chains, we can use the same security source to perform 10 times the work.

Highly specialized parallel chains serve another purpose: they can implement data storage and trading operations in the most efficient way for their domain of expertise, without getting bogged down in a blockchain-specific scripting language or virtual machine. Models like Bitcoin scripts and EVM are designed with interoperability goals in mind at their core, but systems that use these models pay an increasing cost of execution for all implementation parts, not just those that are accessible from other systems running on the same network. In contrast, Polkadot parallel chains communicate with each other through asynchronous messaging, thus paying for data consistency only at the boundaries where parallel chains intersect.

Note that you can still create a parallel chain that provides the framework for a fully universal and Turing complete intelligent contract. A simple example is parallel chains driven by EVM. For these reasons, contracts executed on the parallel chain also suffer from the inconvenience of benefiting from the universality and interoperability of the Ethereum smart contract. The main difference is that it is fully opt-in. We think Polkadot's ability to integrate a focused solution while retaining the optionality of using an extremely generic framework is one of its most powerful features.

One of the most interesting use cases for parallel chains is as a tool for extensibility.You can create parallel chains that have their own parallel chains, and so on. This creates a tree structure that can be used to perform highly distributed computations without reducing the overall burden of the root trunk chain itself. The main issue is ensuring data availability -- parallel chain blocks should be accompanied by validation that anyone can use for at least a certain period of time. The verifier is responsible for ensuring that the proof of the block it validates is still available. Unfortunately, without moving the message along the chain, it is impossible (or at least difficult) to prove that the message that should have been sent was not sent. We can avoid this problem by making a credibility pledge: relatively trusted parties are punished when they use the verifier as hiding data. This could also be extended to token voting systems or multi-tier courts. In order to reduce the effectiveness and practicality of malicious and false reports, each improper report should be accompanied by a non-refundable expense. When enough people are watching the calculation, such as in the case of the first parallel chain, the necessary data is usually available. Another strategy for mitigating risk is to design parallel chains so that when the chain stagnates or is attacked, the value stored can be recovered, although this is difficult to achieve when the chain executes smart contracts to automatically lock up funds or manage its own expenses.

Perhaps a more interesting approach to scalability is to use zero knowledge (ZK) proof. Modern non-interactive ZK proofs, such as zk-Snarks or Zk-Starks, allow us to check a proof to see if a known program with some known and unknown inputs has executed correctly and to understand what the output of the program is without revealing anything about the private input. Most commonly, ZK proofs like this are called privacy tools, but they can also be used to improve performance: surprisingly, the time to check this zero-knowledge proof is mostly constant, regardless of the complexity of the program itself, and the time to verify the proof is less than the execution time of the corresponding program! This means that even very complex transactions, which can take hours of processing time, can be verified in a short time by a verifier in the chain. Unfortunately, the computational and memory costs of creating ZK proofs are still higher than the average user would accept. Until these costs come down, using ZK in practice will prove to be wishful thinking.

However,The great thing about parallel chains is that they are very generic. By allowing each parallel chain to define its own concept of validity, we can move seamlessly from the current large proof to the future lighter, more advanced proof. With the development of sharding research, parallel chains using the latest technology can be easily added. Ultimately, this is Polkadot's value proposition: it is at the right level of abstraction and can be used now and in the future without any unnecessary overhead. The system is designed not only to adapt to arbitrary evolution, but also to be scalable and able to integrate the latest technology effortlessly.

Text link:https://mp.weixin.qq.com

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