You can create your own agents by developing simple services that implement ActiveWorkflow's Remote Agent API. “Remote” in this context means that agents run in separate processes from ActiveWorkflow itself. Communication between agents and ActiveWorkflow takes place via HTTP. Each agent is effectively an HTTP service or microservice which ActiveWorkflow interacts with via an RPC protocol.
https://github.com/automaticmode/active_workflow/blob/master/lib/remote_agents.rb
https://github.com/automaticmode/active_workflow/blob/master/spec/features/use_remote_agent.rb
https://github.com/automaticmode/active_workflow/blob/master/spec/lib/remote_agents_spec.rb