What is the abstraction for a Worker process in Spark code

[Muhammad Haseeb Javed]

I understand that each executor that is processing a Spark job is emulated
in Spark code by the Executor class in Executor.scala and
CoarseGrainedExecutorBackend is the abstraction which facilitates
communication between an Executor and the Driver. But what is the
abstraction for a Worker process in Spark code which would a reference to
all the Executors running in it.