condition_aggregator_jma 0.1.2

JMA (気象庁) adapter for the condition_aggregator interface. Maps JMA disaster-info XML feeds to source-neutral Advisory typed events. Pure Dart.

condition_aggregator_jma

Japan Meteorological Agency (気象庁 / JMA) adapter for the condition_aggregator interface. Maps JMA disaster-info XML feeds to the source-neutral Advisory typed event shape so integrators consume one shape across publishers (NWS / JMA / etc.) without caring which publisher authored which advisory.

Status

0.1.0 — deployed via direct-Dart-XML-parse path. The provider fetches the JMA atom feed (https://www.data.jma.go.jp/developer/xml/feed/extra_l.xml by default), filters to prefecture-class 気象警報・注意報 reports, parses each linked per-prefecture XML directly with the canonical Dart xml package, and surfaces winter-snow-class advisories (大雪警報 / 大雪注意報 / 暴風雪警報 / 暴風雪注意報 / 着雪注意報) as source-neutral Advisory records.

The jmaxml engagement-shape election (alpha/beta/gamma) for an upstream typed binding remains a separate open question (OQ-1) and does not block this version's publish. A future major version may swap the direct-parse path for the elected binding; the public API is shaped so the swap does not produce churn.

What this package does

When JMA has issued a 大雪 / 暴風雪 / 着雪 advisory for the driver's current point in Japan:

1. The provider fetches the JMA atom feed (extra_l) over HTTPS with a contactable User-Agent.
2. Atom entries are filtered to the prefecture-class warning report titles and to the caller's prefecture code (resolved from lat/lon via a bounding-box catalog at 0.1.0; 6 snow-zone prefectures: Hokkaido / Aomori / Iwate / Akita / Yamagata / Niigata).
3. The linked per-prefecture report XML is fetched and parsed for <Information type="気象警報・注意報（市町村等をまとめた地域等）"> (most-granular block) <Item><Kind><Name> events.
4. Events whose JA name matches the snow-class catalog (kJmaSnowAdvisoryEventNames) are mapped to source-neutral Advisory records via mapJmaForecastToAdvisory.
5. The AdvisoryAggregator merges the JMA records with sibling adapters' records (e.g. condition_aggregator_nws records when the driver crosses an international boundary or relies on multi-source corroboration).
6. The integrator HMI surfaces the typed Advisory event with severity / certainty / urgency / area / effective / expires normalized at the boundary, with JMA's exact wording preserved verbatim per Article 17 (β) verbatim-relay discipline.

Driver-facing loom

When JMA has issued a snow / heavy-snow / blizzard advisory for the driver's current point on a Japanese road, the integrator HMI surfaces a typed Advisory event normalized into the same shape as NWS records. The driver sees JMA's authoritative wording verbatim (event name, area name, headline) without aggregator-class re-summarization. The driver always drives.

HER-trace (≤4 hops)

JMA disaster-info atom feed (気象庁防災情報XML)
  → JmaAdvisoryProvider (this package; HTTP + XML parse + filter)
  → AdvisoryAggregator (typed merge with sibling adapters)
  → integrator HMI surfaces advisory to driver in unexpected snow.

4 hops. D3 anchor: helps the driver in unexpected snow on a Japanese road. D5 value chain: evidence → contribution → architecture → edge developer → driver.

What this package does NOT do

• No retry inside this adapter. Transient failure handling belongs to the integrator's polling cadence; the aggregator's warn-and-continue posture captures the error through AdvisoryAggregateResult.providerErrors.
• No cache, no stream, no polling at this layer. Stateless beyond construction-time configuration; consumer owns refresh cadence.
• No app-class re-summarization. JMA's headline and event name pass through verbatim.
• No profile-driven branching. Profile-aware UX rendering composes downstream against navigation_safety_core thresholds.
• No road-surface inference. JMA's domain at this report family is meteorological-advisory; road-surface measurement lives in JARTIC / NEXCO / prefectural feeds.
• No prefecture catalog past 6. Points outside the 6-prefecture catalog return empty without an HTTP fetch. Catalog expansion is a deliberate version bump.
• No CAP-class certainty / urgency mapping. certainty and urgency are unknown at 0.1.0; the publisher's authoritative term is preserved verbatim in eventClass either way.

Severity mapping

• 特別警報 (emergency warning) suffix → AdvisorySeverity.extreme
• 警報 (warning) suffix → AdvisorySeverity.severe
• 注意報 (advisory) suffix → AdvisorySeverity.moderate
• otherwise → AdvisorySeverity.unknown

The publisher's authoritative event name is preserved in Advisory.eventClass either way per Article 17 (β).

Getting started

import 'package:condition_aggregator/condition_aggregator.dart';
import 'package:condition_aggregator_jma/condition_aggregator_jma.dart';

final jma = JmaAdvisoryProvider(
  userAgent: '(myappname.example, https://example.com/contact)',
);
await jma.init();
final advisories = await jma.fetchActiveAdvisoriesAtPoint(
  latitude: 39.7186, // Akita-shi
  longitude: 140.1024,
);
for (final a in advisories) {
  print('${a.eventClass} (${a.severity.name}) — ${a.areaDescription}');
  // → 大雪警報 (severe) — 秋田中央
}

Composition with the NWS sibling adapter:

final aggregator = AdvisoryAggregator(providers: <AdvisoryProvider>[
  jma,
  nws,
]);
await aggregator.init();
final result = await aggregator.fetchActiveAdvisoriesAtPoint(
  latitude: 39.7186,
  longitude: 140.1024,
);
// result.advisories carries records from both publishers in the
// source-neutral envelope; result.providerErrors surfaces any
// per-publisher transient failure honestly.

License

BSD-3-Clause. See LICENSE.

Publisher attribution

JMA disaster-info XML feed is open public-data class. Per the publisher's Terms of Use (https://www.jma.go.jp/jma/en/copyright.html linked from the feed's <rights> element), credit is recommended. The AdvisorySource.jmaJapan.attributionString extension renders the canonical credit line for driver-facing surfaces.