---
id: DYN-8
family: GR-DYN
level: extended
profiles: [storage-api, editor-client]
posture: normative-target
added: "1.0"
changed: "1.0"
source: https://flowdrop.io/spec/rules/gr-dyn/dyn-8
specification: FlowDrop Workflow Specification 1.0
licence: CC BY 4.0
---

# DYN-8 — A node's ports are its effective schemas, with dynamic ports overlaid

*GR-DYN (Part I) · level: extended · profiles: storage-api, editor-client · added in 1.0*

A dynamic port definition is configuration that adds one property to the node's input or output schema. Once it is overlaid, the port is a port like any other, and no rule needs to say anything special about it.

## The rule

> **Normative.** This is the rule.
>
> 1. A node's ports MUST be read from its effective schemas: the node type's parameter schema overlaid with the node's `dynamicParameters`, and its output schema overlaid with its `dynamicOutputs`.
>
> 2. Each definition MUST add one property named after it.
>
> 3. Where the definition carries a `schema` (DYN-2), the property MUST be that schema.
>
> 4. Otherwise the property MUST carry the definition's lane in `x-data-type`, and the JSON Schema `type` that lane stands for: `string`, `number`, `boolean` and `array` for the lanes of those names, `object` for `json`, and no `type` for `mixed`.
>
> 5. Where the lane is a shape, the property MUST carry the shape's own top-level `type` where the shape declares one, and nothing more of the shape (SCH-42).
>
> 6. A property the node type declares MUST win over a definition of the same name (DYN-5).
>
> 7. An overlaid parameter MUST take the gate flags its definition carries (DYN-2), and the derived input and config schemas MUST split it as any parameter (SCH-3, SCH-6).
>
> 8. An overlaid port's default exposure MUST be its definition's `exposedByDefault` where the definition states one (DYN-2), and exposed where it does not (CFG-2).
>
> 9. The overlay MUST be computed from the node's stored definitions wherever a node's ports are read: at save, when the node is enriched, when a contract is built and when the node runs.
>
> 10. It MUST NOT be computed from a value delivered at run time (DYN-7).
>
> 11. Every rule that reads a node's ports reads them from its effective schemas.

## Why

Recorded under [OPEN-25](https://flowdrop.io/spec/rulings/open-25), [OPEN-31](https://flowdrop.io/spec/rulings/open-31), [OPEN-33](https://flowdrop.io/spec/rulings/open-33).

## Fixtures

Test cases whose outcome this rule decides (fixtures/README.md defines each operation):

- An unwired dynamic input is absent; a null on its wire is present (`resolve-parameters`): fixtures/presence/dyn-unwired-absent-null-present.json

## Related rules

- Names: DYN-1, DYN-5, DYN-6, DYN-7

---

Rule identifiers are permanent and are never renumbered. This specification carries
no implementation status: each implementation publishes its own standing against
these rules. Licensed CC BY 4.0.