Build an executor bot

This page will go over some concepts which are important when building an EES executor bot, whether it be for profit or to ensure processing of jobs related to your own application.

Execution module specific logic

Execution modules determine crucial information such as:

• When the job can be executed

• Who can execute the job

• How much the execution fee will be

• The execution fee token

All of these are necessary to avoid failed or unprofitable transactions. Since each execution module contains its own rules, it is important to implement custom logic to each of those you wish to support.

Off-chain computation

All information necessary to determine if a job is profitable and can be executed is stored inside the job's execution module. Execution module data is stored as Param structs inside the params mapping. To avoid unnecessary RPC calls it can be advantateous to query the state once and update it locally by listening for events.

Listen for events

Events emitted from the JobManager will tell when a job is created, executed or deleted. It is also beneficial to listen for execution module specific events such as if the fee function has changed.

Parallelisation

Since all jobs are stored in the public jobs array, execution can easy be parallelised. The array can simply be split into even sections that each executor bot takes care of.

The BatchExecutor contract

BatchExecutor is a contract which enables executing multiple jobs in a single batch. Even if one of the jobs fails to be executed, the transaction as a whole will not revert. This protects against someone executing a job just before you, reverting the whole batch. Furthermore, it returns a receipt for each successful payments processed containing information about the fee received.

Correct for protocol fee

The JobManager contract splits the execution fee calculated by the execution module in two: one part to the protocol and one part to the executor. It is therefore crucual to implement into your calculations to know when a job is profitable to execute or not. Read more about this and how to calculate it here.

Strict gas price monitoring

Strict gas price monitoring is crucial to implementing a profitable executor bot. The profit you can make on executing a specific job is primarily depending on the current gas price together with how large the received execution fee is. Having live gas monitoring will give you an edge over other executor bots.