Files
scadaproj/ZB.MOM.WW.Health/README.md
T
Joseph Doherty 91fb2b48dd docs(health): GrpcDependencyHealthCheck has no consumers - keep it, correct SPEC/README (scadaproj#28)
SPEC 2.4 named OtOpcUa and MxGateway as users; neither is (verified against every
app's default branch; MxGateway worker IPC is named pipes, OtOpcUa deliberately
does not gate readiness on gateway channels). Keep the check (removal is a breaking
API change; small, tested building block), mark it as no-current-consumers in SPEC
2.4/6/7, both READMEs, the shared-contract doc and GAPS.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
2026-11-09 14:19:09 -05:00

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4.5 KiB
Markdown

# ZB.MOM.WW.Health
Health-check libraries for the **ZB.MOM.WW SCADA family** (OtOpcUa, MxAccessGateway, ScadaBridge). These are **libraries, not a service** — each package is linked directly into the consuming application at build time. There is no central health process or network hop; probes run in-process alongside the application.
The library normalizes the three-tier health endpoint convention (`/health/ready`, `/health/active`, `/healthz`) and provides reusable probe implementations so the three sister projects share a common surface without duplicating probe logic.
---
## Packages
| Package | Description | Key Dependencies |
|---|---|---|
| `ZB.MOM.WW.Health` | Core tiers, `MapZbHealth` extension, canonical JSON writer (`ZbHealthWriter`), `IActiveNodeGate` seam, `GrpcDependencyHealthCheck` reachability probe (available; no app currently uses it), and tier-tag constants (`ZbHealthTags`). No Akka or EF dependency. | `Microsoft.AspNetCore.App` (framework ref), `Grpc.Net.Client` |
| `ZB.MOM.WW.Health.Akka` | `AkkaClusterHealthCheck` with a configurable `AkkaClusterStatusPolicy` (presets: `Default` three-way / `OtOpcUaCompat` two-way), `ActiveNodeHealthCheck` with an optional role filter, and `AkkaActiveNodeGate` that backs `IActiveNodeGate` from the cluster member state. | `ZB.MOM.WW.Health`, `Akka.Cluster` |
| `ZB.MOM.WW.Health.EntityFrameworkCore` | `DatabaseHealthCheck<TContext>` with `CanConnectAsync` by default and an optional `ProbeQuery` delegate for custom connectivity validation. | `ZB.MOM.WW.Health`, `Microsoft.EntityFrameworkCore` |
---
## Consumer Matrix
| Consumer | `ZB.MOM.WW.Health` (core) | `ZB.MOM.WW.Health.Akka` | `ZB.MOM.WW.Health.EntityFrameworkCore` |
|---|:---:|:---:|:---:|
| **OtOpcUa** | yes | yes | yes |
| **MxAccessGateway** | yes | — | — |
| **ScadaBridge** | yes | yes | yes |
MxAccessGateway consumes the core package only — it has no Akka cluster and no EF DbContext. OtOpcUa and ScadaBridge consume all three packages.
---
## Versioning
All three packages are versioned **lockstep** from `Directory.Build.props`. The current release is **0.2.0**. A single version bump in `Directory.Build.props` bumps all three packages simultaneously — consumers should reference the same version for all ZB.MOM.WW.Health packages.
### 0.2.0 — per-entry `data` (additive, non-breaking)
- `ZbHealthWriter` emits an optional `"data": { … }` object per entry, sourced from the check's
`HealthCheckResult.Data`, **only when non-empty** — a check that publishes no data produces a
byte-identical body to 0.1.0, so every existing consumer is unaffected. Data keys are written
verbatim (the camelCase policy applies to the envelope, not to dictionary keys).
- `AkkaClusterHealthCheck` populates that dictionary with this node's cluster view: `leader`
(omitted while unknown), `selfAddress`, `selfRoles`, `memberCount`, `unreachableCount`. The
startup-safety paths (no `ActorSystem`, cluster not yet accessible) stay description-only.
- Consumers gain the leader field on a package bump alone — no application code change, provided the
app registers the shared `AkkaClusterHealthCheck`.
---
## Building and testing
```bash
# from ZB.MOM.WW.Health/
dotnet build ZB.MOM.WW.Health.slnx
dotnet test ZB.MOM.WW.Health.slnx
```
All three test assemblies run with `dotnet test` and require no external dependencies — no database and no
external cluster (the cluster-data tests form a single-node in-process Akka cluster on a loopback port
via `Akka.TestKit.Xunit2`):
| Assembly | Tests |
|---|---|
| `ZB.MOM.WW.Health.Tests` | 25 |
| `ZB.MOM.WW.Health.Akka.Tests` | 39 |
| `ZB.MOM.WW.Health.EntityFrameworkCore.Tests` | 6 |
| **Total** | **70** |
---
## Packing
```bash
dotnet pack ZB.MOM.WW.Health.slnx -c Release -o ./artifacts
```
Produces three `.nupkg` files in `artifacts/`:
```
ZB.MOM.WW.Health.0.2.0.nupkg
ZB.MOM.WW.Health.Akka.0.2.0.nupkg
ZB.MOM.WW.Health.EntityFrameworkCore.0.2.0.nupkg
```
`GeneratePackageOnBuild` is off — pack explicitly as above.
---
## Status
**Built at 0.2.0 and published to the Gitea NuGet feed. Adopted by all four apps** (OtOpcUa, MxAccessGateway, ScadaBridge, HistorianGateway). Adoption is tracked in the component backlog:
- `~/Desktop/scadaproj/components/health/GAPS.md`
Design documentation lives alongside that backlog:
- `~/Desktop/scadaproj/components/health/spec/SPEC.md` — normalized three-tier target
- `~/Desktop/scadaproj/components/health/shared-contract/ZB.MOM.WW.Health.md` — proposed API
- `~/Desktop/scadaproj/components/health/current-state/` — per-project current state (code-verified)