API Integration

A .NET 10 backend that proxies Fingrid Open Data with PostgreSQL caching, real-time SignalR viewer count, Polly resilience, and rate limiting.

Architecture

Clean Architecture with four layers:

Layer	Purpose
Domain	Entities, interfaces, value objects
Application	DTOs, mappers, service interfaces
Infrastructure	EF Core, PostgreSQL repositories, migrations
Presenter.API	Controllers, services, SignalR hub, DI, middleware
SharedKernel	Error record, Result pattern
Unit test	Unit test cases

Key features:

• DB caching — batched PostgreSQL upsert with background cleanup
• Polly — outer timeout (3 min) → retry (3x on 429) → inner timeout (30s per attempt)
• SignalR — live viewer count via /hubs/dashboard
• Rate limiting — fixed window per endpoint
• Security — input validation, HSTS, sanitized error responses, Azure Key Vault

Prerequisites

• .NET 10.0 SDK
• PostgreSQL
• A Fingrid API key (free registration)

Getting Started

1. Clone

git clone https://github.com/BasilOmsha/api-integration.git
cd api-integration

2. Configure secrets

Store the API key and database connection string using .NET User Secrets:

cd api-integration.Presenter.API
dotnet user-secrets set"ConnectionStrings:fingrid""YOUR_FINGRID_API_KEY"
dotnet user-secrets set"ConnectionStrings:postgres""Host=localhost;Port=portnumber;Database=api_integration;Username=YOUR_USER;Password=YOUR_PASSWORD"

Verify:

dotnet user-secrets list

3. Run database migrations

From the solution root ('*\api-integration>'):

dotnet ef database update --project api-integration.Infrastructure --startup-project api-integration.Presenter.API

4. Run

cd api-integration.Presenter.API
dotnet watch

The server starts at:

• HTTP:http://localhost:5143
• HTTPS:https://localhost:7285
• scalar:http://localhost:5143/scalar (development only)

Database Migrations

Create a new migration after changing entities or AppDbContext:

dotnet ef migrations add MigrationName --project api-integration.Infrastructure --startup-project api-integration.Presenter.API

Apply migrations:

dotnet ef database update --project api-integration.Infrastructure --startup-project api-integration.Presenter.API

Revert to a specific migration:

dotnet ef database update PreviousMigrationName --project api-integration.Infrastructure --startup-project api-integration.Presenter.API

API Endpoints

Base path:/api/v1/fingrid-meta-data

Method	Route	Description
GET	/{datasetId}	Get cached metadata for a Fingrid dataset (1–999)
GET	/{datasetId}/data?startTime=...&endTime=...	Get time-series data (checks cache first, then Fingrid API)

Query parameters for the data endpoint:

• startTime — ISO 8601 UTC datetime
• endTime — ISO 8601 UTC datetime

Example:

GET /api/v1/fingrid-meta-data/75/data?startTime=2025-03-01T00:00:00Z&endTime=2025-03-02T00:00:00Z

Configuration

Defaults in appsettings.json / appsettings.Development.json:

{
"FingridApi": {
"BaseUrl": "https://data.fingrid.fi/api/datasets/",
"TimeoutSeconds": 30,
"MaxRetryAttempts": 2,
"RetryDelayMs": 1000
}
}

Azure Key Vault is used in production for secrets. The vault URI is configured in appsettings.json under KeyVault:VaultUri.

Data Source

All data comes from Fingrid Open Data, licensed under Creative Commons Attribution 4.0.