cpn_routing

CPN Guard-Based Routing Example

Routes a batch of orders to approved or review purely by YAML-declared guards that inspect each token's own data (token.amount). No routing logic lives in Go — the guards decide.

Run it:

go run ./examples/cpn_routing/

Output:

Received 4 orders at 'pending'.
Routing each order — the transition guards decide, not this program:
  A-1  amount 500   → auto-approved
  A-2  amount 1500  → manual review
  A-3  amount 250   → auto-approved
  A-4  amount 9000  → manual review

Result: approved=2  review=2  pending=0

How it works

The workflow is loaded entirely from workflow.yaml. Orders are seeded as colored tokens via initial_marking, and two transitions leave pending, each with a guard on the token being fired:

initial_marking:
  pending:
    - {order_id: "A-1", amount: 500}
    - {order_id: "A-2", amount: 1500}
transitions:
  - {name: auto_approve,  from: [pending], to: [approved], guard: "token.amount <= 1000"}
  - {name: manual_review, from: [pending], to: [review],   guard: "token.amount > 1000"}

ApplyTransitionForToken(ctx, name, id) fires a transition only if its guard accepts that token — a blocked guard returns an error and leaves the token in place, so the program simply tries each candidate transition in turn:

switch {
case wf.ApplyTransitionForToken(ctx, "auto_approve", tok.ID()) == nil:
    // guard token.amount <= 1000 passed
case wf.ApplyTransitionForToken(ctx, "manual_review", tok.ID()) == nil:
    // guard token.amount > 1000 passed
}

Inside a guard expression, the token being fired is token (a data map), so token.amount reads that order's amount. See docs/guides/CPN_GUIDE.md.