JSR 354 Java Money and Currency API

Werner KeilBuild Manager, DevOps Expert,

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EG Member, JSR 354@wernerkeil

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• JCP Executive Committee Member

•Eclipse UOMo Project Lead

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Werner Keil - BioWerner Keil - Bio

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Show me the Money!Show me the Money!

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AgendaAgenda

•History

•Motivation

•The JSR

•Virtual Currencies

•Currency Exchange

•Demos

•Q&A

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HistoryHistory

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Earlier ApproachesEarlier Approaches

Martin Fowler: A large proportion of the computers in this world manipulate money, so it's always puzzled me that money isn't actually a first class data type in any mainstream programming language. The lack of a type causes problems, the most obvious surrounding currencies…

see http://martinfowler.com/eaaCatalog/money.html

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Earlier Approaches (2)Earlier Approaches (2)

Eric Evans – Time and Money: On project after project, software developers have to reinvent the wheel, creating objects for simple recurring concepts such as "money" and "currency". Although most languages have a "date" or "time" object, these are rudimentary, and do not cover many needs, such as recurring sequences of time, durations of time, or intervals of time. …see http://timeandmoney.sourceforge.net/

To be quite frank, their code isn‘t more than an academic POC, factories called dollars() or euros() are useless in real globally deployed frameworks, but he made a good point.

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MoneyDanceMoneyDance

Motivation

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SummarySummary

•This JSR will providea money andcurrency API forJava, targeted at all users of currencies andmonetary amounts in Java.

•TheAPI will providesupportfor standard ISO-4217 and Custom (e.g. Virtual) currencies, as well asrepresentation of a monetary amount.

• It will supportcurrency arithmetic, even across different currencies, and foreign currency exchange.

•Additionally, implementation details surroundingserialization andthread safety are to be considered

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Why is it needed?Why is it needed?

•Monetary values are a key feature to many applications.

•Theexisting java.util.Currency class is strictly a structure used for representing ISO-4217 standard currencies.

•No standard value type to represent a monetaryamount.

•No support for currency arithmetic or conversion

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ChallengesChallenges

•Keep it simple – Remember the most common use case

•Adding currency values e.g. in an e-commerce app.

•Performance

•How to support low latency applications, such as High Frequency Trading apps.

•Precision

•There can potentially be differing precisions specified for arithmetic, currency exchange and formatting

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Challenges (2)Challenges (2)

•Formatting

•Requirement should be to use existing Number Formats.

•However there is no existing format representing for example Indian Rupees:which might look something like this: 12,34,00,000

•Natural language support for non-decimal valuations for example

•Lakhs

•Crores

•1 Lakh = 100,000

•1 Crore = 100 Lakh

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Challenges (3)Challenges (3)

•Formatting

•12,34,56,000.21 is written12 Crore, 34 Lakh, 56 Thousand Rupees and 21 Paise

•Support for non-standard rounding modes

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Non-standard Rounding ModesNon-standard Rounding Modes

• It is a big world, and each country has its regulations and cultural nuances for expressing currencies in natural language, rounding policies, groupings, etc.

•For example, in Argentina rounding is prescribed for the third digit after the decimal point:If the third digit is 2 or less, change it to 0 or drop it.If the third digit is between 3 and 7, change it to 5.If the third digit is 8 or more, add one to the second digit and drop the third digit or change it to 0.

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Non-standard Rounding – ArgentinaNon-standard Rounding – Argentina

Argentina Rounding Examples

Switzerland uses a similar rounding strategy.

Original Number

Rounded Notes

123.452 123.45 Third digit<3 round down

123.456 123.455 3<=third digit<=7 change to 5

123.459 123.46 Third digit>=8 round up

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RisksRisks

Plan – “Money and Currency” is a formidable and dynamic category with regional dependencies, requiring programmers, business users, international accountants, and attorneys.

Risk – Incomplete or outdated spec

Mitigation – Resulting API should be flexible, let application developer

change implementation as needed.

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Risks (2)Risks (2)

Plan – There is also a Java dependency on JDK NumberFormat.

Risk – NumberFormat may require coordinated modifications.

Mitigation – Coordinate with JDK release;

Supply NumberFormats and similar classes that augment JDK content.

Plan – There is also a Java dependency on JDK NumberFormat.

Risk – NumberFormat may require coordinated modifications.

Mitigation – Coordinate with JDK release;

Supply NumberFormats and similar classes that augment JDK content.

The JSR

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Expert Group MembersExpert Group Members

•Credit Suisse

•Goldman Sachs

•Stephen Colebourne

•Ben Evans

•Werner Keil

•Bob Lee

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Supporting the JSRSupporting the JSR

•Credit Suisse

•Caxton Associates

•Goldman Sachs

• JP Morgan/Chase

•London Java Community

•Stephen Colebourne

•Werner Keil

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ScheduleSchedule

•Targeted to Java 9

•Aiming at Java ME/Embedded 8 or 9• Following the EC Merge and Standard/Embedded harmonization, no JSR

should be SE/EE or ME only, with very few, specialized exceptions. Money is so important, and has almost no legacy in the JDK except java.util.Currency, that it should be supported by ALL POSSIBLE platforms, except maybe JavaCard for now.

•With back-port to previous versions still supported and in relevant use

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Virtual CurrenciesVirtual Currencies

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Facebook CreditsFacebook Credits

What are Facebook Credits?

•Facebook Credits are a virtual currency you can use to buy virtual goods in any games or apps of the Facebook platform that accept payments. You can purchase Facebook Credits directly from within an app using your credit card, PayPal, mobile phone and many other local payment methods.

► Hence any such purchase is practically a conversion, similar to if you buy a foreign currency when

travelling abroad☺

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Top 10 Video Game CurrenciesTop 10 Video Game Currencies

1.Gold

2.Gil

3.Rupees (not Indian;-)

4.Credits

5.Gold Rings

6.Hearts

7.Zenny

8.Potch

9.Munny

10.Nuyen

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World CurrenciesWorld Currencies

Currency ExchangeCurrency Exchange

Currency Conversion (JScience)Currency Conversion (JScience)

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Online Currency Conversion ExampleOnline Currency Conversion Example

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Trading Application ExampleTrading Application ExampleWhat happens, if we use built in java.util.Currency and Standard

JSP formats

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Demos

Q & A

• The JSR: http://jcp.org/en/jsr/summary?id=354

• java.net Project: http://java.net/projects/javamoney/

• GitHub Project: http://github.com/JavaMoney/

LinksLinks

• Eclipse UOMo: http://www.eclipse.org/uomo/

• JScience:http://www.jscience.org

• JodaMoney: http://joda-money.sourceforge.net/

Links (2)Links (2)