Scheduling & Constraints

Aerie provides related frameworks for defining constraints and scheduling new activities in the plan, and two implementations of those frameworks: one for arbitrary procedures that run on the JVM, and a legacy system based on a declarative Typescript eDSL (embedded Domain-Specific Language). Both frameworks are documented here, but new users are encouraged to focus on creating JVM procedures. The declarative eDSL is significantly less capable, and the difference in capabilities is only expected to grow.

Constraints

Constraints represent what is nominal for a plan or mission model, and when executed, the UI will display "violations" whenever the plan or model is off-nominal. They don't alter the behavior of the simulation engine or scheduler; they just serve as a warning, indicating that some requirement - perhaps a flight rule - was broken.

Scheduling

The scheduler allows users to automate the creation of new activities, to remove some cognitive load from planners. A scheduling specification contains a list of goals and rules with a priority order; during a scheduling run, they are executed one at a time, starting from a priority of 0 and increasing from there.

Procedural Goals

Procedural goals directly edit the plan, creating new activities at definite (grounded) times. They can simulate potential changes to the plan, but aren't required to. In fact, a scheduling specification composed entirely of procedures might run in its entirety without performing any simulations, potentially at the cost of optimality or even soundness.

eDSL Goals

eDSL goals are more declarative, in that they don't allow you to directly create grounded activities; instead they allow you to describe a pattern of activities that should be present in the plan. If the pattern isn't found, the goal tries to create it for you. Currently eDSL goals are simpler to write than procedural goals, for patterns that they can represent. Many goals are more complex than can be represented in the eDSL, and will have to be written as a procedure.

Global Conditions

Global scheduling conditions (or sometimes just "conditions") are supplemental pieces of code that define when scheduling goals can and cannot place activities. They are incorporated into the solver when attempting to resolve conflicts as a substitute for constraints. This is because it is too difficult to respect constraints during scheduling; constraints only indicate that something went wrong, not what caused it or how to fix it. So in cases when the scheduler keeps violating constraints, users can create a condition as a heuristic to help it satisfy the constraint.

Conditions will be accessible to scheduling rules, but will be non-binding.