Polkadot WIKI

https://wiki.polkadot.network/en/latest/polkadot/build/build-with-polkadot/

parachain

An in-development extension to Substrate called Cumulus will allow any Substrate built chain to connect to Polkadot and become a parachain.

two ways for you to deploy your application:

• as a smart contract on an existing parachain,

• as your own parachain

Cumulus - a Polkadot-ready parachain

The goal of Cumulus is to be an extension of Substrate that will make any Substrate runtime compatible with Polkadot.

relay chain

relay chain itself will not support smart contracts

One project that has announced intent to become a Polkadot parachain with support for smart contracts is Edgeware.

https://edgewa.re/

• Rob's talk from EthCC introducing Cumulus

Relay chain

https://github.com/darwinia-network/darwinia

parachain

https://github.com/paritytech/cumulus

https://github.com/nczhu/parachain

https://github.com/alekspickle/basic_parachain

https://github.com/UltronAGI/substrate-ultron

test-parachains

git clone https://github.com/paritytech/polkadot.git

open source examples

Substrate Runtimes¶

Parity¶

• Shasper- Eth2.0 implemented as Substrate runtime.
• Substrate TCR- Token curated registry as a runtime module.
• Substrate ERC20 - ERC20 token standard implemented on Substrate.

Community¶

• AdEx Payment Channels using Substrate. Video. Repo.

• Robonomics modules for integrating with ROS. Repo

• Plasma on Substrate implemented by Staked Technologies. Repo

• Edgeware. Repo

• Zerochain privacy-focused runtime module.

• Zero-chain Repo

• Bellman-substrate (zksnarks on substrate) Repo

• Starlog, IPFS metadata on substrate. Repo

• An example "Apple Store" to sell apples using Substrate. Repo

• Darwinia, a cross-chain gaming platform. Repo

• Joystream, a user governed video platform. Repo

• IPFS browser. Repo

• Substrate multisig. Repo

• Merkle tree module. Repo

• Parking spaces registry using Substrate. Repo

• Substrate inherents sample. Repo

• Collateralize non-fungible assets for cash. Repo

• CidChain. Repo

• Katal. Repo

• Fixed-point arithmetic

• Time in ISO8601 format

• Permissioned Oracle

Ideas¶

• NFT
• Bonded Tokens
• New governance modules with different styles of voting & democracy
• Upgrade the TCR module
• IPFS integration
• Decentralized identity solutions
• Oracle module
• Implement Generalized State Channel/Plasma Chain
• Decentralized Exchange
• Tools for monitoring validator performance
• dApps across different parachains

A parachain has two major value adds that make it a desirable choice for a developer over creating a standalone chain:

• Shared security - removes the necessity of bootstrapping a chain's own validator set.
• Interchain communication - allows parachains to interoperate with each other through the ICMP protocol.

What is a PDK?¶

As mentioned, a PDK is a set of tools that allows developers to easily create a parachain. In practice this means that the PDK will consist of a couple key components:

• State transition function - a way for your application to move from one state to another state.
• Collator node - a type of peer-to-peer node in the Polkadot network with certain responsibilities in regard to parachains.

a collator node also acts as a light client for the Polkadot relay chain

https://wiki.polkadot.network/en/latest/polkadot/learn/parachains/

https://wiki.polkadot.network/en/latest/polkadot/learn/staking/

https://wiki.polkadot.network/en/latest/polkadot/learn/bridges/

Transaction on the relay-chain will likely be priced higher than they will be on parachains.

https://research.web3.foundation/en/latest/polkadot/GRANDPA/

Bridge¶

A node which acts as an intermediary between the Polkadot relay chain and an external chain, in such a way that it appears to the relay chain that the external chain is a parachain (i.e., meets the Polkadot Runtime Environment requirements). Bridges allow for interaction between other blockchains such as Ethereum and Bitcoin which are not natively compatible with Polkadot.

Collator¶

A node which maintains a parachain by collecting parachain transactions and producing state transition proofs for the validators.

Overview¶ICMP

• Interchain messages will not go on to the relay chain.
• Interchain messages will be constrained to a max size in bytes.
• Parachains are allowed to block messages from other parachains, in which case the dispatching parachain would be aware of this block.
• Collator nodes are responsible for routing messages between chains.
• Collators produce a list of "egress" messages and will receive the "ingress" messages from other parachains.
• On each block, parachains are expected to route messages from some subset of all other parachains.
• When a collator produces a new block to hand off to a validator, it will collect the latest ingress queue information and process it.
• Validators will check a proof that the new candidate for the next parachain block includes the processing of the expected ingress messages to that parachain.

为什么parachain和smart contract进行比较呢？

；；；有点水，还没看完，看完再做进一步整理；；；