Class FrankfurterExchangeRates

java.lang.Object

com.eqixiac.equinix.design.cost.FrankfurterExchangeRates

All Implemented Interfaces:

CurrencyConverter

public final class FrankfurterExchangeRates
extends Object
implements CurrencyConverter

Live ECB reference rates from the Frankfurter API (no key): one GET <baseUrl>/latest?base=<target> per converter, made on the first conversion that needs it and cached for the converter's life; never retried. The request carries only the currency code and a generic User-Agent. Shape observed 2026-11-12: {"amount":1.0,"base":"USD","date":"2026-11-11","rates":{"EUR":0.89871,"GBP":0.75149,...}} (no AED).

When the call fails, times out (3 s connect, 5 s overall) or returns another shape, or a currency is absent, rate(String, String) is empty so the chain falls back to the bundled table; fallbackNote() says why. Never throws. Rates are reference mid rates, not dealing rates, so converted ranges are widened by 2.0% either side.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	FrankfurterExchangeRates.Fetcher	Fetches a URL's body; injectable so tests never reach the internet.

Nested classes/interfaces inherited from interface CurrencyConverter

CurrencyConverter.Converted, CurrencyConverter.Kind, CurrencyConverter.Rate

Modifier and Type	Interface	Description
static final record	CurrencyConverter.Converted	An amount restated in another currency.
static enum	CurrencyConverter.Kind	Where a rate came from, in precedence order.
static final record	CurrencyConverter.Rate	A rate between two currencies.

Field Summary

Fields

Modifier and Type	Field	Description
static final double	BAND_PERCENT	Widening for live ECB reference rates, either side, in percent.
static final String	DEFAULT_BASE_URL	The default endpoint root.

Constructor Summary

Constructors

Constructor	Description
FrankfurterExchangeRates(String target, String baseUrl, FrankfurterExchangeRates.Fetcher fetcher)

Method Summary

Modifier and Type	Method	Description
boolean	attempted()
Optional<String>	fallbackNote()
static FrankfurterExchangeRates.Fetcher	httpFetcher()
String	name()
Optional<CurrencyConverter.Rate>	rate(String from, String to)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface CurrencyConverter

convert

Modifier and Type	Method	Description
default Optional<CurrencyConverter.Converted>	convert(BigDecimal amount, String from, String to)	Converts an amount.

Field Details

DEFAULT_BASE_URL

public static final String DEFAULT_BASE_URL

The default endpoint root.

See Also:

• Constant Field Values

BAND_PERCENT

public static final double BAND_PERCENT

Widening for live ECB reference rates, either side, in percent.

See Also:

• Constant Field Values

Constructor Details

FrankfurterExchangeRates

public FrankfurterExchangeRates(String target,
 String baseUrl,
 FrankfurterExchangeRates.Fetcher fetcher)

Parameters:

target - the currency rates are fetched for (the request's base)

baseUrl - the endpoint root, null for DEFAULT_BASE_URL

fetcher - the HTTP fetch, null for httpFetcher()

Method Details

httpFetcher

public static FrankfurterExchangeRates.Fetcher httpFetcher()

Returns:

a java.net.http fetch with a 3 s connect and 5 s request timeout and a generic User-Agent

rate

public Optional<CurrencyConverter.Rate> rate(String from,
 String to)

Specified by:

rate in interface CurrencyConverter

Parameters:

from - ISO 4217 code

to - ISO 4217 code

Returns:

the rate, or empty when this converter has none for the pair

fallbackNote

public Optional<String> fallbackNote()

Returns:

why live rates were not used, empty when they were fetched (or no conversion needed them yet)

attempted

public boolean attempted()

Returns:

whether the single fetch has been attempted

name

public String name()

Specified by:

name in interface CurrencyConverter

Returns:

a short name for reasons and diagnostics