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docs: secured-writes tag selector + MxGateway browse DataType

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Joseph Doherty
2026-06-27 13:24:26 -04:00
parent ce4d5f0639
commit c4daf941d2
2 changed files with 2 additions and 2 deletions
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docs/requirements/Component-DataConnectionLayer.md
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@@ -197,7 +197,7 @@ DCL is a clean data pipe on the hot path. Browse is an **opt-in capability** for
- `OpcUaDataConnection` and `MxGatewayDataConnection` both implement `IBrowsableDataConnection`; other/custom protocols do not (and return a `NotBrowsable` failure).
- `DataConnectionManagerActor` handles `BrowseNodeCommand` (fields: `ConnectionName`, `ParentNodeId`, and an optional opaque `ContinuationToken` for paging) and replies with `BrowseNodeResult` (children + `Truncated` + an optional continuation token + structured `BrowseFailure?`). The Central UI facade is `IBrowseService`/`BrowseService`, backing the `NodeBrowserDialog` tag picker.
- **Browse type-info** (OPC UA): each child `BrowseNode` carries optional best-effort type metadata — `DataType` (friendly name), `ValueRank` (scalar/array), and `Writable`. `RealOpcUaClient` batch-reads these attributes for **Variable** nodes during browse and maps built-in data-type node ids to friendly names; non-Variable rows leave them unset.
- **Browse type-info**: each child `BrowseNode` carries optional best-effort type metadata — `DataType` (friendly name), `ValueRank` (scalar/array), and `Writable`. `DataType` is populated by **both** OPC UA and MxGateway: `RealOpcUaClient` batch-reads built-in data-type node ids and maps them to friendly names for **Variable** nodes; `MxGatewayDataConnection` surfaces each attribute leaf's `GalaxyAttribute.data_type_name` (free-form Galaxy type text) as `DataType`. `ValueRank` and `Writable` are OPC-UA-only; MxGateway leaves them unset.
- Node ids are opaque protocol-specific strings: OPC UA uses NodeIds; MxGateway uses Galaxy gobject ids for navigable objects and full tag references for selectable attribute leaves.
- Browse runs against the live session; no caching at DCL.
- **Frame-size guard**: the reply crosses the site→central Akka frame (default 128 KB) on a temp Ask actor; an oversized reply is silently discarded by remoting, hanging the picker. The child handler caps each `BrowseNodeResult` to a byte budget (~100 KB) before replying, OR-ing the adapter's own truncation signal into `Truncated`. This is protocol-agnostic (every adapter's reply funnels through it). Per-protocol upstream caps narrow the window first: OPC UA requests at most 500 references per node (continuation point → `Truncated`); MxGateway relies on the gateway's `BrowseChildren` page cap.