Practice.Backend.CurrencyConverter.Client 1.0.93

Practice.Backend.CurrencyConverter.Client

A typed, DI-friendly HTTP client library for the Currency Converter API. Publish as a NuGet package to share across services or environments.

Features

• Typed ICurrencyConverterClient interface — easy to mock in tests
• Configurable base URL — supports local, staging, and production environments
• JWT bearer authentication via pluggable ITokenProvider
• Built-in resilience: exponential retry + circuit breaker (via Microsoft.Extensions.Http.Resilience)
• Options validation on startup — misconfiguration fails fast
• Fully compatible with IHttpClientFactory and Microsoft's generic host

Installation

dotnet add package Practice.Backend.CurrencyConverter.Client

Quick Start

1. Configure via appsettings.json

{
  "CurrencyConverterClient": {
    "BaseUrl": "https://api.example.com",
    "ApiVersion": "1",
    "TimeoutSeconds": 30,
    "Retry": {
      "MaxAttempts": 3,
      "InitialDelaySeconds": 2
    },
    "CircuitBreaker": {
      "FailureRatio": 0.5,
      "BreakDurationSeconds": 60,
      "SamplingDurationSeconds": 60,
      "MinimumThroughput": 30
    }
  }
}

2. Register in DI

// From configuration section (recommended)
services.AddCurrencyConverterClient(
    builder.Configuration.GetSection(CurrencyConverterClientOptions.SectionName));

// Or inline
services.AddCurrencyConverterClient(options =>
{
    options.BaseUrl = "http://localhost:9081";
    options.TimeoutSeconds = 15;
});

3. Add Authentication (optional)

Option A — forward the incoming bearer token (ASP.NET Core apps):

services.AddDefaultHttpContextTokenProvider();

This forwards the Authorization: Bearer ... header from the current HTTP context — useful when the calling service already has a Keycloak token.

Option B — custom provider:

public class KeycloakTokenProvider(IKeycloakClient keycloak) : ITokenProvider
{
    public async Task<string?> GetTokenAsync(CancellationToken ct = default)
        => await keycloak.GetAccessTokenAsync(ct);
}

services.AddSingleton<ITokenProvider, KeycloakTokenProvider>();

If no ITokenProvider is registered, requests are sent without an Authorization header.

4. Inject and use

public class MyService(ICurrencyConverterClient client)
{
    public async Task<decimal> GetEurToUsdRateAsync(CancellationToken ct)
    {
        var response = await client.GetLatestExchangeRatesAsync(
            new LatestExchangeRatesRequest { BaseCurrency = "EUR" },
            ct);

        return response.Rates.GetValueOrDefault("USD");
    }

    public async Task<decimal> ConvertAsync(decimal amount, CancellationToken ct)
    {
        var response = await client.GetConversionAsync(
            new ConversionRequest { BaseCurrency = "EUR", ToCurrency = "USD", Amount = amount },
            ct);

        return response.Rates.GetValueOrDefault("USD");
    }
}

API

ICurrencyConverterClient

All methods throw CurrencyConverterApiException on API errors.

CurrencyConverterApiException