Webhybridhigh risk

Web maps and plugins: legacy scripts to a governed browser boundary

Replace global-script assumptions with explicit origin restrictions, lifecycle ownership, typed adapters, accessible fallbacks, and measured rendering parity.

Adjacent Evidence

Candidate capability evidence, not one-to-one replacement

The Mappls web repositories are adjacent modern evidence, not proof that every legacy plugin or GeoAnalytics surface has a one-to-one replacement. Select map, API, widget, analytics, or application-owned UI per journey with Mappls confirmation.

Re-contract the integration

Resolve each dimension explicitly. “It compiled” does not prove identity, lifecycle, failure, privacy, or operational compatibility.

DimensionLegacy exposureCandidate targetRequired proof
Loading

Global scripts and callbacks can be coupled to page order and mutable globals.

Load once behind an application adapter and expose an explicit ready/error lifecycle.

Cold/warm navigation tests prove one instance, deterministic cleanup, and content-security-policy compatibility.

Credentials

Keys may be embedded without a complete origin inventory.

Use only browser-supported credentials restricted to exact production and development origins.

Inspect built assets, network logs, restriction configuration, and rejected-origin behavior.

Experience

Plugin UI and behavior may be product-owned and difficult to customize.

Choose a supported widget or rebuild the journey over documented primitives.

Accessibility, visual, interaction, empty/error, mobile, and slow-network acceptance tests.

Compatibility matrix

  • Package, wrapper, native runtime, build tool, operating-system, and architecture versions are recorded together.
  • Credentials are classified by client/server use, restricted to the exact environment, and never copied between generations by assumption.
  • Normalized fixtures cover success, zero results, invalid input, authentication, quota, timeout, offline, cancellation, and malformed provider data.
  • Telemetry distinguishes legacy and candidate generations without logging credentials, precise private locations, or raw provider bodies.
  • Every state-changing operation has an idempotency, reconciliation, ownership, and ambiguous-outcome policy before cutover.
  • Rendering parity covers camera, bounds, projection, markers, layers, controls, gestures, accessibility, printing, and high-density datasets.

Six stages, each with an exit gate

Do not advance on calendar alone. Each stage creates evidence that makes the next one safe and reversible.

  1. 01

    Freeze the baseline

    Inventory every map or plugin integration, package, host, credential class, callback, and owner before changing production.

    Deliverable
    A signed baseline manifest, representative fixtures, latency/error measurements, and a dependency lockfile.
    Exit gate
    The current build is reproducible and its externally visible behavior is covered by contract tests.
  2. 02

    Prove the candidate

    Resolve the exact entitled package or endpoint with Mappls and verify its supported toolchain, region, quotas, authentication, and lifecycle.

    Deliverable
    An approved compatibility matrix linked to source fingerprints and an account-specific entitlement record.
    Exit gate
    No candidate is inferred only from a similar repository name; the owning product team confirms the integration line.
  3. 03

    Install an adapter seam

    Move map or plugin integration calls behind a narrow application-owned interface without changing product behavior.

    Deliverable
    A legacy adapter, candidate adapter, normalized domain types, safe error taxonomy, and dependency-injection switch.
    Exit gate
    The same journey tests run against either adapter without UI or domain-code changes.
  4. 04

    Compare safely

    Replay approved fixtures and shadow eligible reads while preventing duplicate writes or user-visible map mutations.

    Deliverable
    A privacy-reviewed parity report covering results, ordering, geometry, errors, latency, resource use, and lifecycle behavior.
    Exit gate
    Every material difference is accepted, fixed, or converted into an explicit product decision.
  5. 05

    Cut over by cohort

    Release to internal users and bounded cohorts with health gates, ownership, automatic stop conditions, and immutable version evidence.

    Deliverable
    A staged rollout record with cohort, package/data versions, success metrics, support routing, and stop/go decisions.
    Exit gate
    The target service level and full-journey acceptance criteria hold through the agreed observation window.
  6. 06

    Retire deliberately

    Remove legacy credentials and dependencies only after rollback and audit retention obligations expire.

    Deliverable
    Revocation evidence, dependency removal, archived compatibility report, updated runbooks, and owner sign-off.
    Exit gate
    No runtime, build, secret, dashboard, or operational process depends on the retired line.

Make the provider replaceable before replacing it

These examples deliberately model the seam and verification pattern—not unconfirmed package symbols. Implement the adapters only after the exact target contract is issued.

Web migration seam
export type MapPort = {
  mount(container: HTMLElement): Promise<void>;
  showPlaces(features: ReadonlyArray<{ id: string; lng: number; lat: number }>): void;
  fitTo(ids: ReadonlyArray<string>): void;
  destroy(): void;
};

export async function runMapJourney(port: MapPort, host: HTMLElement) {
  await port.mount(host);
  port.showPlaces([{ id: "fixture-store", lng: 77.2, lat: 28.6 }]);
  port.fitTo(["fixture-store"]);
  return () => port.destroy(); // listeners, workers, and map resources end together
}

Evidence required to cut over

  1. 1

    The candidate and exact package/endpoint versions are approved by the owning Mappls product team for the target account and region.

  2. 2

    Journey-level contract tests pass on every supported device, browser, architecture, and release build—not only a debug simulator.

  3. 3

    Security, privacy, accessibility, performance, quota, observability, and support owners accept measured differences.

  4. 4

    A bounded cohort completes the agreed observation window without an unresolved severity-one or severity-two regression.

Rollback is a product journey

Stopping traffic is not enough. Recover durable resources, sessions, events, and in-flight commands without duplicates or hidden divergence.

Prepare support packet
  1. 01

    Keep the previous signed artifact, dependency lock, configuration, and credential valid until the observation window closes.

  2. 02

    Make the provider selection server- or release-controlled; define automatic stop signals and one accountable rollback owner.

  3. 03

    For durable state, prove backward-readable records or a reversible data migration before allowing candidate writes.

  4. 04

    After rollback, reconcile in-flight requests and resources by stable identifiers instead of replaying commands blindly.