Bodu.Financial.ExchangeRates.Boe 0.7.1

Bodu.Financial.ExchangeRates.Boe

API stability — Preview. The public API surface is largely settled but is still being finalized ahead of the 1.0 release and may change; breaking changes can land in a minor version until then.

A Bodu.Financial exchange-rate provider backed by the Bank of England's daily spot exchange rates, queried from the Bank's Interactive Statistical Database (IADB).

It builds an IADB CSV query for the configured series over a date range, parses the response with the Bodu.Text.Formats RFC 4180 reader, and serves the results as Bodu.Financial.ExchangeRates.ExchangeRate values through the standard IDatedRateProvider and IRateProvider contracts — so it composes with Money.ConvertTo, the caching and aggregating providers, and the rest of the Bodu.Financial FX stack.

using Bodu.Financial.ExchangeRates;

// The provider builds and owns its HttpClient from the options; dispose it to release the client.
using var provider = new BoeRateProvider(new BoeRateProviderOptions());

// Warm the cache for a range (recommended), then look rates up synchronously.
await provider.LoadRangeAsync(new DateOnly(2023, 1, 1), new DateOnly(2026, 6, 30));

RateLookupResult usd = provider.GetRate("GBP", "USD", new DateOnly(2023, 1, 3));
// usd.Rate.Rate is the number of US dollars per pound on that date.

// Read a whole range at once (GBP-based pairs; the reverse direction is inverted). The result is
// an IReadOnlyList<ExchangeRate> that also reports the requested window and the observed span.
RateRangeResult series =
    await provider.GetRatesAsync("GBP", "JPY", new DateOnly(2026, 1, 1), new DateOnly(2026, 6, 12));

// Discover what pairs the loaded data supports.
foreach (BoeSeriesInfo info in provider.GetAvailablePairs())
    Console.WriteLine($"{info.Pair.FromIsoCode}/{info.Pair.ToIsoCode} ({info.SeriesCode})");

Behaviour

• GBP-based. The Bank of England quotes each currency's daily spot rate against the pound (one IADB series per currency, for example XUDLUSS for the US dollar). Direct (GBP→X) and inverse (X→GBP) lookups are supported; cross pairs are not.
• Range queries. The IADB is queried by date range rather than by fixed file, so loading is range-based. LoadRangeAsync fetches an inclusive range; a synchronous lookup that misses an unloaded date blocks to download a bounded window around it (configurable via OnDemandWindowDays) only when AllowSynchronousNetworkAccess is enabled (it is false by default, so the provider serves a snapshot of already-loaded data and a synchronous miss does not reach the network).
• Caching. Downloaded range responses are cached on disk (configurable) and refreshed on a TTL, since a range ending near today can gain an observation each business day.
• Configuration. BoeRateProviderOptions carries working defaults and binds through Microsoft.Extensions.Options. The provider's connection to the IADB is grouped under its Endpoint (BoeEndpointOptions) — base URL, query path, HTTP timeout, and user-agent — so the query can be pointed at a mirror or proxy without touching caching or series configuration. The package ships its own AddBoeExchangeRates registration in the Bodu.Financial.ExchangeRates namespace.

HTTP client and lifetime

The provider is IDisposable and offers two construction styles:

• new BoeRateProvider(options, ...) — the provider builds, owns, and disposes its own HttpClient, created via RateProviderHttpClientFactory.Create from the configured user agent and timeout. Dispose the provider (for example with using) to release the client.
• new BoeRateProvider(httpClient, options, ...) — you supply the client and own its lifetime; the provider never disposes a client it did not create. This is the form the *.DependencyInjection package uses, backed by IHttpClientFactory.

Logging

The provider logs through Microsoft.Extensions.Logging. Pass an ILogger to the constructor, or let the *.DependencyInjection package wire one for you (category Bodu.Financial.ExchangeRates.BoeRateProvider). When no logger is supplied it defaults to NullLogger.Instance, so logging is entirely opt-in and free when unused.

The levels follow the conventions used by Microsoft.Extensions.Http, EF Core, and the Azure SDK — the completed download is the one Information line per range loaded, payload detail is Trace, and degraded paths are Warning. Every level is individually configurable on BoeRateProviderOptions:

// Quieten the per-range line and turn off per-observation tracing entirely.
var options = new BoeRateProviderOptions
{
    DownloadCompletedLogLevel = LogLevel.Debug,
    ObservationIngestedLogLevel = LogLevel.None,
};

The default verbosity is deliberately low: at Information you see one line per range loaded; at Debug you additionally see when downloads start; only at Trace do you get a line per rate observation (which can be thousands per range — keep it for targeted debugging).

Part of the Bodu utility library.