93 lines
2.9 KiB
Markdown
93 lines
2.9 KiB
Markdown
# Consumer API Guide
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## Purpose
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This guide is for developers and LLM coding agents integrating `weatherfeeder`
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from another Go codebase.
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`weatherfeeder` is primarily a daemon, not an SDK. Its public integration
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surface is intentionally narrow:
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- `model`: canonical weather payload structs.
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- `standards`: schema strings, event kind strings, and shared WMO constants.
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- JSON event output from stdout and NATS sinks.
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- Postgres tables written by the optional Postgres sink.
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Packages under `internal/` are implementation details and are not public
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integration surfaces.
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## Recommended Workflow
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Consumers should switch on the event `schema` value and decode `payload` into
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the matching `model` type.
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Minimal example:
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```go
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package consumer
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import (
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"encoding/json"
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"fmt"
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"gitea.maximumdirect.net/ejr/weatherfeeder/model"
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"gitea.maximumdirect.net/ejr/weatherfeeder/standards"
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)
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type Event struct {
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ID string `json:"id"`
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Kind string `json:"kind"`
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Schema string `json:"schema"`
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Payload json.RawMessage `json:"payload"`
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}
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func Decode(payload []byte) (any, error) {
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var evt Event
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if err := json.Unmarshal(payload, &evt); err != nil {
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return nil, err
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}
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switch evt.Schema {
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case standards.SchemaWeatherObservationV1:
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var out model.WeatherObservation
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return &out, json.Unmarshal(evt.Payload, &out)
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case standards.SchemaWeatherForecastV1:
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var out model.WeatherForecastRun
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return &out, json.Unmarshal(evt.Payload, &out)
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case standards.SchemaWeatherForecastDiscussionV1:
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var out model.WeatherForecastDiscussion
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return &out, json.Unmarshal(evt.Payload, &out)
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case standards.SchemaWeatherStoryV1:
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var out model.WeatherStoryRun
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return &out, json.Unmarshal(evt.Payload, &out)
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case standards.SchemaWeatherAlertV1:
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var out model.WeatherAlertRun
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return &out, json.Unmarshal(evt.Payload, &out)
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case standards.SchemaWeatherOutlookV2:
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var out model.WeatherOutlookRun
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return &out, json.Unmarshal(evt.Payload, &out)
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default:
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return nil, fmt.Errorf("unsupported weatherfeeder schema %q", evt.Schema)
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}
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}
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```
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## Consumer Responsibilities
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- Treat event IDs as opaque.
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- Treat absent `omitempty` fields as unknown, not zero.
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- Prefer schema constants from `standards` over string literals in Go code.
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- Expect canonical numeric measurements to use metric units.
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- Expect canonical timestamps from normalizers to be UTC unless a field-specific
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contract says otherwise.
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- Handle additive fields within the same schema version.
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- Do not import `internal/...` packages.
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## Canonical References
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- Public payload package: [`pkg-model.md`](pkg-model.md).
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- Public constants package: [`pkg-standards.md`](pkg-standards.md).
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- JSON event wire contract: [`../integrations/events.md`](../integrations/events.md).
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- Postgres table contract: [`../integrations/postgres.md`](../integrations/postgres.md).
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- Runtime and adapter architecture: [`../policy/architecture.md`](../policy/architecture.md).
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