Technical Perspectives | How do ordinary users earn miners in cross-chain?

Inscription: As a distributed ledger technology, blockchain can be applied in many fields such as finance, health care, supply chain, asset management, etc., but it is restricted by factors such as throughput, network isolation, scalability, etc. Blockchain projects do not serve commercial applications well. Among the many problems faced by blockchains, network isolation hinders the cooperative operation between different blockchains, which greatly limits the space for blockchains.

I. Introduction

In the previous technical point of view article, we introduced in detail the core modules of the ontology chain, the block header synchronization contract and the cross-chain management contract. The ontology verifies the cross-chain transaction through these two modules. Today we mainly introduce the dApp contract for applying cross-chain technology, and the information state synchronizer Relayer. The dApp contract is an application contract that implements a cross-chain business, while Relayer is responsible for synchronizing cross-chain information and charging a certain miner fee.

Figure | Network

Among them, anyone can become a Relayer without registering, as long as the running status information synchronization service program is deployed and related synchronization work can be performed.

Second, the pass contract and dApp contract

Pass contract
A pass is a specific digital asset contract that enables the transfer of cross-chain assets. On the basis of the original certificate, in order to achieve cross-chain business, the license and contract have added the Lock and Unlock interfaces:

1. Lock interface

Lock assets on the chain. The interface invokes a cross-chain management contract, and the transaction for the locked asset is placed in the merkle tree by the cross-chain management contract.

2. Unlock interface

Unlock assets on the chain. The interface is invoked by a cross-chain management contract, and the cross-chain management contract passes the verified transaction parameters to the interface, and the interface unlocks the assets according to the parameters.

dApp contract
The dApp contract is a cross-chain application contract implemented by the user. In addition to the user's own business logic, the cross-chain business needs several sets of interface pairs like Lock and Unlock, and the inter-chain call is realized through the cross-chain management contract.

Third, the state information synchronization player Relayer

Anyone can become a Relayer without registering, as long as the running state information synchronization service program is deployed, the cross-chain request and the cycle switching block of the cross-chain contract are continuously monitored, and the cross-chain transaction or the block header synchronization is performed. Only one Relayer of the same cross-chain transaction or block header can be successfully submitted. After Relayer successfully submits a cross-chain transaction, it can get incentives for miners. Relayer does not require a mortgage deposit, and sets the threshold for miners to determine whether to synchronize transactions with lower miners' fees.

Figure | Network

Relayer needs to synchronize two key pieces of information in a cross-chain interaction: key block headers and cross-chain transactions. The cost of a cross-chain transaction is paid by the user to the Relayer that carries the data. The key block header may not contain cross-chain transactions, so there may be no one paying the cost of moving the key block. However, the key block head has an impact on the cross-chain transaction of the entire cycle. If no one synchronizes the key block information, the cross-chain transaction of the entire cycle after the key block cannot be completed. Therefore, a portion of the cost of the cross-chain transaction for the entire cycle is used to motivate the Relayer to carry the key block headers.

Figure: Main chain to side chain miner fee transfer

Users of cross-chain transactions can submit cross-chain trading information themselves, or they can include a miner fee in a cross-chain transaction to commission Relayer to synchronize cross-chain transactions. Specifically, when the user conducts a cross-chain transaction on the source chain, it needs to additionally lock a part of the pass or destroy part of the pass as the miner fee. After listening to the cross-chain request, Relayer will charge according to whether the miner is higher than the miner. Set your own threshold to decide whether to submit this cross-chain transaction.

Figure | Network

When it is higher than the miner's fee threshold set by itself, Relayer will submit the cross-chain transaction to the target chain. After the cross-chain transaction is successfully executed, the release on the target chain will correspond to the pass or the additional certificate corresponding to the miner. The fee, this pass will be transferred to the Relayer that submitted this cross-chain transaction successfully, used to motivate the Relayer.

Figure: Side chain to main chain miner fee transfer

Fourth, postscript

In future technical viewpoint articles, we will bring you more specific details about cross-chain design.