Polkadot is a blockchain for scalable decentralized computing and interoperability. In this article, well examine a major part of this network: parachains.
Blockchains today come in a fairly standard form, consisting of two parts.The first part is the consensus algorithm, which provides security.The second part is the state machine, which provides every aspect of a chain that is worth gaining security on. Ethereum, Bitcoin, Zcash, and other cryptocurrencies are all secured by Proof-of-Work (PoW) consensus and its variants, but they process different types of transactions and accounts (the things that make up their unique state machine). Imagine a developer coming up with a great idea for a new blockchain that could provide effective privacy protection, wealth distribution, or some other exciting feature. As developers work on implementing this unique state machine, they must also implement some kind of consensus algorithm, and when they launch a chain, it must compete with other chains for secure resources. This brings cost and insecurity to developing new blockchain projects.
Let me introduce the parachain.Parachains (parallelizable chains) are a simpler form of blockchain that connect to the security provided by a relay chain instead of providing security itself.It is called a relay chain because it not only provides security to the attached parachains, but also guarantees secure messaging between them. A key property of parachains is that the computations they perform are inherently independent. A fully generalized system of Turing-complete smart contracts would have problems determining which transactions would collide with each other, meaning transactions that could be parallelized would run sequentially, wasting valuable computation time. Drawing boundaries between parachains means we can execute all of them at once without worrying about “collisions” — if we have 10 parachains, we can perform 10 times the work with the same security source.
Highly specialized parachains alsoAnother purpose: they can implement data storage and transaction operations in the most efficient way for their problem domain, without getting bogged down in blockchain-specific scripting languages or virtual machines.At their core, models such as Bitcoin Script and the EVM are designed with the goal of interoperability in mind, however, systems using these models pay higher execution costs for all parts of their implementation, not just Only those parts that are accessible from other systems running on the same network. In contrast, Polkadot parachains communicate with each other via asynchronous message passing, so the cost of data consistency is only paid at the boundaries where the parachains intersect.
Note that you can still create a parachain that provides the framework for fully generalized, Turing-complete smart contracts. A simple example is a parachain powered by the EVM. Based on the above reasons, contracts deployed in this parachain will not only benefit from the versatility and interoperability of Ethereum smart contracts, but also bringinconvenient. The main difference is that its completely opt-in.We think Polkadot is able to integrate focused solutions while retaining one of its strongest features - optionality - using a very general framework.
One of the most interesting use cases for parachains is as a scalability tool. Parachains can be created with their own parachains, etc. This creates a tree structure that can be used to perform highly distributed computations without reducing the overall burden on the root relay chain itself. The main issue is ensuring the availability of data - parachain blocks are meant to have a proof of validity that anyone can check for at least a period of time. Validators are responsible for ensuring that the block proofs they validated are still available. Unfortunately, without deleting the message on-chain, it is impossible (or at least very difficult) to prove that a message that should have been sent was not sent. We can largely avoid this problem with reputation guarantees: when a relatively trusted party points out that validators are hiding data, they can be punished. This can also be generalized to coin voting systems or multi-level courts. To reduce the effectiveness and usefulness of malicious false reports, every report of bad behavior should be accompanied by a non-refundable destruction of funds. When enough people are computing, as in the case of level 1 parachains, the necessary data is usually obtained. Another mitigation strategy is to design parachains so that stored value can be extracted when the chain stalls or is attacked, although this is difficult when the chain executes smart contracts to lock funds or automatically manage its own fees.
but,
but,The great thing about parachains is that they are so versatile. By allowing each parachain to define its own concept of validity, we can seamlessly transition from bulky proofs today to lighter, more advanced proofs in the future. As sharding research develops, parachains implementing the latest technology can easily be added. finally,This is the value proposition of Polkadot: its at the right abstraction layer and can be used now and in the future without any unnecessary cost。Translation: PolkaWorld, the first Chinese community of Polkadot
Original link:https://medium.com/polkadot-network/polkadot-the-parachain-3808040a769a
Translation: PolkaWorld, the first Chinese community of Polkadot
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