Orchestrator API - StartJob


I am looking to implement a workflow in which a monitoring robot will make an API call to another robot and instruct it to run a specific process.

In the Orchestrator 2016.2 API StartJob action appears to be close to what I want, but it appears to be intended for scheduled jobs (as it requires a ReleaseKey). What would be the correct way to call a robot via Orchestrator API to run any deployed process when the process is not scheduled?