Integration Guide for Builder

The Builder API Specification defines the standard interface that builders should implement, while the specific implementation is left open to MEV API providers. The BNB Chain community offers a simple implementation example for reference.

Customize Builder

Although the builder offers great flexibility, there are still some essential standards that must be followed:

1. The builder needs to set up a builder account, which is used to sign the block bid and receive fees. The builder can ask for a tip (builder fee) on the block that it sends to the sentry. If the block is finally selected, the builder account will receive the tip.

2. The builder needs to implement the mev_reportIssue API to receive the errors report from validators.

3. In order to prevent transaction leakage, the builder can only send block bids to the in-turn validator.

4. At most 3 block bids are allowed to be sent at the same height from the same builder.

Here are some sentry APIs that may interest a builder:

1. mev_bestBidGasFee. It will return the current most profitable reward that the validator received among all the blocks received from all builders. The reward is calculated as: gasFee*(1 - commissionRate) - tipToBuilder. A builder may compare the bestBidGasFee with a local one and then decide to send the block bid or not.

2. mev_params. It will return the BidSimulationLeftOver,ValidatorCommission, GasCeil and BidFeeCeil settings on the validator. If the current time is after (except block time - BidSimulationLeftOver), then there is no need to send block bids any more; ValidatorCommission and BidFeeCeil helps the builder to build its fee charge strategy. The GasCeil helps a builder know when to stop adding more transactions.

Builders have the freedom to define various aspects like pricing models for users, creating intuitive APIs, and define the bundle verification rules.

Setup with Example Builder

Step 1: Find Validator Information

For validators that open MEV integration, the public information is shown at bsc-mev-info. Builders can also provide information here to the validator.

Step 2: Set up Builder.

The builder must sign the bid using an account, such as the etherbase account specified in the config.toml file.

[Eth.Miner.Mev]
BuilderEnabled = true # open bid sending
BuilderAccount = "0x..." # builder address which signs bid, usually it is the same as etherbase address

Configure the validator node list, including the address of the validator and the public URL. The public URL refers to the sentry service.

[[Eth.Miner.Mev.Validators]]
Address = "0x23707D3D...6455B52B3"
URL = "https://bsc-fuji.io"

[[Eth.Miner.Mev.Validators]]
Address = "0x52825922...3A1A7A422"
URL = "http://bsc-mathwallet.io"

Step 3: Publish information

It is highly recommended to publish information in bsc-mev-info.