Bring external evidence into your application
Generic observations let an application use external information through a shared verification policy. For example, a workflow can wait for a signed shipment report before deciding what happens next.
The network call happens outside deterministic execution. Members use the same accepted, certified input when they apply the application rules.
Follow a delivery report
Section titled “Follow a delivery report”- Request an observation. The application identifies what it needs and binds the request to the relevant order or payment.
- Acquire the evidence. A configured adapter or reporter obtains data outside consensus. Sources, identities, bounds, and acceptance rules are selected in advance.
- Check and certify. The host verifies the reports and source evidence required by the configured policy. A report arriving is not itself a finalized observation result.
- Apply the result. The application consumes the finalized observation callback and makes its next deterministic transition. Missing or rejected evidence must be handled as an explicit outcome.
The shipment reference shows a signed Merkle receipt bound to a payment transaction. It combines stable Cardano payment observations, a generic delivery observation, an external payment effect, and a separate Cardano settlement observation.
What the evidence means
Section titled “What the evidence means”A valid source signature and inclusion proof establish what the authorized attestor committed. They do not prove that a parcel physically arrived or that a source is honest. The source trust policy remains part of the application design. Generic observations do not replace Cardano validation.
The ADA/USD reference demonstrates multiple source reports and deterministic aggregation with synthetic fixtures. It is a teaching example, not a production price oracle.
Observations, roles, and effects
Section titled “Observations, roles, and effects”| Need | Capability |
|---|---|
| Bring supported external evidence into the application | Generic observations |
| Decide who may propose or approve a business action | Domain roles and approvals |
| Authorize work in an external system after a transition | Effects |
Yano owns the observation protocol, verification, certification, and callbacks. Yano X provides application examples and domain behavior through the plugin catalog. Observation profiles and source policies are pinned inputs; follow the version-matched reference before creating a new application identity. The examples are preview workflows, not production escrow or oracle products.