Adding Constraints

Constraints are entities that model restrictions on how to perform certain actions. There are a few different kind of constraints, such as the delivery windows of consignments or visiting certain stops, or the type of vehicle that is supposed to drive a certain trip because of demands the goods have (i.e. temperature or size).

The reason Constraints are entities and not a data type is because elaborate constraints might need to reused over and over again. An environmental zone will need to be complied to at pre-determined times during the week, being able to reference existing constraints makes communicating about these restrictions easier.

Time fields vs time constraints

Note that time constraints are different from the startTime and endTime present on actions. The startTime and endTime model that something will be/is/was happening within those time slots. For example, delivering a package between 10:00 and 10:15. However the TimeWindowsConstraint model that something has to happen within (usually) a wider slot. For example, when you order a package, you often get to pick a 'shift' (e.g. between 09:00 - 13:00 or 13:00 - 17:00). The stops within the trip might change and your original time of between 10:00 and 10:15 can change, but the constraints remains the same.

An example of stop with both planned start and end times, as well as a constraint could look like this:

{
  "actionType": "stop",
  "id": "d3ada5d6-8007-4742-8ff0-ad06919d39a4",
  "lifecycle": "planned",
  "startTime": "2020-11-06T10:30:00Z",
  "endTime": "2020-11-06T10:45:00Z",
  "constraint": {
    "entity": {
      "value": {
        "startTime": "2020-11-06T09:00:00Z",
        "endTime": "2020-11-06T12:00:00Z",
        "type": "timeWindowsConstraint"
      }
    },
    "associationType": "inline"
  }
}

You can interpret this that the stop is planned to arrive at 10:30 and leaves again at 10:45. However, it should arrival after 09:00 and leave againm before 12:00 according to the constraint.

TimeWindowsConstraint vs StartDateTimeConstraint and EndDateTimeConstraint?

Since version 5.2 OTM supports two ways of providing time-related constraints. The new version, timeWindowsConstraint makes it easier to provide both a lower bound (arrive after) and upper bound (leave before). Before you had to use the startDateTimeConstraint and endDateTimeConstraint toghether with an andConstraint to model the same thing. Since the new version is shorter and more readable the old startDateTimeConstraint and endDateTimeConstraint are deprecated.