Workflow.Retarget (re-base the SLA clocks)

Summary#

Workflow.Retarget() re-evaluates every live SLA clock on the current run — the whole-instance Deadline, the current state's Expire, and each milestone's Within — against the entity as it stands now. Use it when a handler body has just changed the values those budgets are computed from (a severity re-grade, a new contract), so the new, possibly tighter, terms apply immediately. The time already accrued is kept; only the remaining budget is re-based from the change point. It is a no-argument, fire-and-forget effect and returns nothing.

Signature#

Workflow.Retarget();

Description#

A workflow's SLA budgets are expressions over this.Item (Expire = this.Item.SlaResolveWithin, a milestone Within = this.Item.Foo). They are evaluated once, when the clock is armed. If a handler later rewrites those inputs, the armed clocks still hold the OLD budget — Workflow.Retarget() is how you make them reflect the new one.

For each live clock it: re-evaluates the clock's budget expression against the current this.Item; re-resolves the run's ServiceHours (SLA-accrual windows) schedule (which the same handler may also have changed); keeps the SLA time accrued so far; and re-bases the remaining budget from now (remaining = newBudget − accrued, walked through the new schedule). If the new budget is already exhausted the clock is due immediately. A paused clock (the run is in a non-accruing state) keeps its new budget and re-bases when it resumes.

Workflow.Retarget() is only valid inside a workflow handler body (it acts on the enclosing run). It runs on the same transaction as the body, so the new terms and the re-based clocks commit together.

Examples#

Re-grade a ticket and re-base its clocks in one route body:

enum Severity { Low, High }
enum TicketState { Open, Done }

entity SlaTarget {
  [Required] Severity Severity;
  TimeSpan RespondWithin;
  security { allow read, create when IsAuthenticated; }
}

entity Ticket {
  [Required, MaxLength(120)] string Title;
  Severity Severity = Severity.Low;
  TimeSpan SlaRespondWithin;
  TicketState State = TicketState.Open;
  security { allow read, create, update when IsAuthenticated; }
}

workflow TicketFlow {
  Tracks  = Ticket.State;
  Initial = Open;
  event Bump(Severity severity);
  state Open {
    subscribe Bump(Severity severity);
    on Bump(Severity severity) {
      this.Item.Severity         = severity;
      var target = SlaTarget.Single(t => t.Severity == severity);
      this.Item.SlaRespondWithin = target.RespondWithin;
            Workflow.Retarget();                                // the new terms take effect from here, not from the origin
    }
  }
  terminal success Done { }
}

See also#

• ServiceHours (SLA-accrual windows) — the schedule the re-based clocks walk (re-resolved on retarget)
• Assigned / Finished (milestones) — the Within budgets that are re-evaluated
• <span class="planned" title="this page is planned and not written yet">workflow-state</span> — the state Expire that is re-evaluated