WeatherAggregator

A .NET 10 orchestration API that fans out to multiple public weather APIs in parallel and returns a consolidated response.

Architecture

WeatherAggregator/
├── Directory.Build.props          ← net10.0, Nullable, ImplicitUsings for ALL projects
├── Directory.Packages.props       ← Central Package Management — all NuGet versions here
├── src/
│   ├── WeatherAggregator.Domain        ← Zero dependencies — enums, interfaces, exceptions
│   ├── WeatherAggregator.Application   ← Wolverine handler, FluentValidation, extension methods
│   ├── WeatherAggregator.Infrastructure← Castle interceptor, typed HttpClients, Autofac module
│   └── WeatherAggregator.API           ← Program.cs, minimal API endpoint, middleware
└── tests/
    ├── WeatherAggregator.Tests.Unit        ← NSubstitute, FluentAssertions, Bogus
    └── WeatherAggregator.Tests.Integration ← WebApplicationFactory + WireMock.Net

Key Patterns

Pattern	Where
Clean Architecture	4 layer project structure
CQRS (Wolverine)	AggregateWeatherCommand + Handler
AOP Interceptor	AuditInterceptor on all 4 HttpClients
Fan-out + Consolidate	Task.WhenAll in handler
Cache-aside	GeocodingClient + IMemoryCache
Options pattern	ServiceClientOptions per service
Anti-Corruption Layer	ExternalDtos → Domain models
Problem Details RFC 7807	GlobalExceptionHandler

Running

1. Open WeatherAggregator.sln in Visual Studio 2022/2026
2. Set WeatherAggregator.API as startup project
3. Press F5
4. Open weather.http and send requests using VS HTTP client

Endpoints

POST /api/v1/weather/aggregate    ← Main orchestration endpoint
GET  /healthz/live                ← Kubernetes liveness probe
GET  /healthz/ready               ← Kubernetes readiness probe (pings external APIs)
GET  /openapi/v1.json             ← OpenAPI spec (development only)

Example Request

POST /api/v1/weather/aggregate
{
  "currentWeather": { "location": "Sydney", "temperatureUnit": "celsius" },
  "airQuality":     { "location": "Sydney" },
  "astronomy":      { "location": "Sydney" },
  "forecast":       { "location": "Sydney", "days": 3 }
}

Example Response

{
  "aggregationId": "AGG-20250510-A3F2",
  "status": "Completed",
  "requestedAt": "2025-05-10T10:00:00Z",
  "completedAt": "2025-05-10T10:00:00.8Z",
  "results": [
    {
      "service": "CurrentWeather",
      "status": "Success",
      "durationMs": 187,
      "data": { "temperature": 22.4, "feelsLike": 21.0, "humidity": 65, ... },
      "errorMessage": null
    }
  ]
}

External APIs Used (all free, no API key)

Service	URL
Current Weather	api.open-meteo.com
Air Quality	air-quality-api.open-meteo.com
Geocoding	geocoding-api.open-meteo.com
Astronomy	api.sunrise-sunset.org
Forecast	api.open-meteo.com

Notes

• No Serilog — uses Microsoft.Extensions.Logging with console provider only.
• Castle AuditInterceptor logs every outbound HTTP call (request + response + duration).
• WolverineFx.FluentValidation runs validators automatically before handlers — no pipeline behaviors needed.
• Central Package Management — all NuGet versions in Directory.Packages.props, never in individual .csproj files.