What is LCMP
LCMP is Darwinia’s Light-client Cross-chain Messaging Protocol(former name: Darwinia Bridge Messages Protocol). It allows one blockchain to send messages to another blockchain as long as they have established messaging channels with each other.
Darwinia is a cross-chain messaging infrastructure. As shown in the figure below, at the protocols layer, Darwinia does not limit cross-chain protocols. LCMP is one of them.
Cross-chain workflow
LCMP is a light-client based protocol. LCMP has two layers in design. one is the truth layer which contains the light-client. Another is the message layer used for sending cross-chain messages. The light-client in the target chain’s truth layer is used to verify messages from the source chain.
As the diagram shows, there are four components that across the source chain and the target chain.
The DApp of App Layer calls send_message of Message Layer to start a cross-chain operation. When send_message is executed, the Relayer forwards the message to the target chain, and the Truth Layer in the target chain checks the message and dispatch the task carried by the message. After dispatched, the Relayer forwards the confirmation message back to the source chain. This process actually includes two cross-chain processes.
General purpose
LCMP is designed to be a general purpose protocol that means LCMP knows nothing about the DApps running on it. LCMP made no assumptions about the application layer.
General purpose cross-chain capabilities break the boundaries of decentralized applications, bringing more possibilities, and in the near future, new applications and new lego ideas will emerge.
Seamless multi-chains in one contract
LCMP will allow developers to choose the best blockchain capabilities for DApps, regardless of which chain the capabilities are on.
Using the SDK provided by Darwinia, developers can build multi-chain DApps just like building ordinary DApps. Developers can take advantage of multiple chains to develop DApps without being limited to one chain. Developers do not need to care about the details of the cross-chain, but only need to select the capabilities of a certain chain in one contract.
This ability to stitch together multiple smart contracts on multiple chains will redefine the way DApps are developed. This is the beginning of the era of multi-chains DApps.
Trustless cross-chain messaging
Light-client based cross-chain is a more decentralized cross-chain solution。Users does not have to trust an individual or party to act honestly. They only need to trust the consensus of the two chains and the code of the smart contracts which is open sourced.
Truth Layer cross-chain mechanisms comparison
There are currently a variety of cross-chain mechanisms, each with their own pros and cons.
Centralized only supports a single cross-chain function like assets transfer. It’s not a decentralized mechanism. And it's the easiest to implement.
MPC is the best extensible mechanism. It can connect different blockchains easily with less effort. But its decentralization and generality are not good.
Oracle based is a well-balanced mechanism. But you need to trust the oracle provider.
Atomic swap is only suit for token swap. So, it’s not a general solution.
Shard/Parachain mechanism works under one consensus. The shards or parachains share the security of the consensus of the blockchain. So, if the consensus is decentralized, the mechanism is decentralized. It’s not easy to implement because It relays on the blockchain architecture. And it’s not allowed to connect to other blockchains.
Rollup mechanism is similar to Shard/Parachain.
Light-client based is also a well-balanced mechanism. It’s more decentralized than Oracle based the mechanism. But it is less extensible than Oracle based mechanism. Because blockchains without smart contracts would be difficult to support such mechanism without modifying the chain code.
About Darwinia Network
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Darwinia is a cross-chain messaging infrastructure, which will provide a reliable and programmable cross-chain platform for decentralized applications. Darwinia will provide developers with an SDK, and developers can easily integrate cross-chain capabilities into their DApps.
Darwinia Network has gained a high reputation and recognition along the way to building the universal cross-chain messaging infrastructure. Darwinia was written in Polkadot light paper as one of the friends of Polkadot and Substrate. And Darwinia was selected to join Substrate Builder Program and Web3.0 Bootcamp, and for the outstanding work in Substrate Builder Program, Darwinia Network was officially awarded the Level 2 badge by Parity. The products and tools developed by Darwinia have been rewarded with three W3F Grants.
「Understanding Darwinia 1–9」Darwinia LCMP, A Light-Client Based Cross-Chain Messaging Protocol was originally published in DARWINIA NETWORK on Medium, where people are continuing the conversation by highlighting and responding to this story.
