Glosarium

Ring Miners

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Ring miners are network participants in the Loopring protocol who manage order rings and ensure trades are completed for all parties involved.

What Are Ring Miners?

Loopring is an Ethereum-based exchange and payment protocol that implements a novel consensus mechanism. To avoid traditional order books and the AMM mechanisms that govern liquidity pools, Loopring employs network participants known as ring miners. 
Ring miners facilitate orders by filling them before they can be completed or canceled. Those who work as ring miners are paid a service fee in the form of LRC tokens which is Loopring protocol's native token or a slip-margin from an order amount.
Ring-Miners are critical components of the Loopring network. Their activities revolve around executing orders with the help of order rings to gain a service fee. There are two types of rewards that ring-miner receive:
The first is the fees in the form of the Loopring (LRC) token generated by the platform. Under this case, the user who creates an order specifies the maximum number of LRC tokens to be rewarded to the ring-miner as a service fee.
Ring miners are also awarded through split margins, which are deducted from the total amount of a specific order. While placing an order, the user can also specify the portion of the margin that can be claimed for a specific order. 

The decision of choosing between fees and margins is up to the ring-miners.

The compensation system in Loopring is intended to help ring miners receive adequate financial reward for the services they deliver during the order ring. It is based on an incentive system so that miners seek out the best exchange rate deals to obtain better split margins or service fees for themselves. Finding the perfect trading deals also ensures that users receive the most value for their traded cryptos, making it a promising win-win situation for both parties involved.

The Loopring smart contract defines how to fill an ordered ring when a ring miner completes it.

If the smart contract can execute the order on either side of the trade, it will perform a direct transfer from the smart contract to the user's wallet. Order rings also make ring-matching possible. Ring-matching completes orders by linking them together and securing multiple trades through multiple users. Order rings distinguish Loopring from other DEXs such as Waves or Bancor.
Let us make an imaginary order to better showcase these practices in action. Karen, Mark, and Dane are all interested in making a trade on the Loopring network. Karen wishes to exchange 2 HNT for 10 ADA, Mark wishes to exchange 21 VET for 1.5 OMG HNT, and Dane wishes to exchange 20 ADA for 40 VET. Ring miners would use ring-matching to combine these dislocated orders into a single order ring, in which Karen would trade her HNT with Mark, Mark would trade his VET with Dane, and Dane would trade his ADA with Karen. Everyone receives their desired coins after this ring order is approved by Loopring's smart contracts.
Except for Mark's, no one's order is filled. Loopring's order sharing would handle the leftovers, which would then be filtered into another order ring until each incomplete order is added up to the complete order.