/airwallex-code-challenge

Primary LanguageKotlin

Airwallex coding challenge

The aim of this exercise is to implement an "alerting" service which will consume a file of currency conversion rates and produce alerts for a number of situations.

This coding exercise can be performed in either Java or Kotlin. The build system is configured to handle both languages.

Input

The format of the file will simulate a stream of currency conversion rates. Each line will be properly structured JSON (http://jsonlines.org/):

{ "timestamp": 1554933784.023, "currencyPair": "CNYAUD", "rate": 0.39281 }

The fields in the JSON record are:

  • timestamp: the timestamp of the record in seconds since UNIX epoch, with fractional seconds specified
  • currencyPair: the sell and buy currencies which the rate relates to
  • rate: the conversion rate

You may assume that for each currency pair, currency conversion rates are streamed at a constant rate of one per second. ie. for two consecutive "CNYAUD" entries in in the input file, they will have timestamps that differ by one second:

{ "timestamp": 1554933784.023, "currencyPair": "CNYAUD", "rate": 0.39281 }
{ "timestamp": 1554933784.087, "currencyPair": "USDAUD", "rate": 0.85641 }
{ "timestamp": 1554933785.023, "currencyPair": "CNYAUD", "rate": 0.39295 }

Output

The alerting service should produce the following alerts, as JSON strings output to standard output:

  • when the spot rate for a currency pair changes by more than 10% from the 5 minute average for that currency pair
  • when the spot rate has been rising/falling for 15 minutes. This alert should be throttled to only output once per minute and should report the length of time of the rise/fall in seconds.

The format of the alerts produced should be:

{ "timestamp": 1554933784.023, "currencyPair": "CNYAUD", "alert": "spotChange" }
{ "timestamp": 1554933784.023, "currencyPair": "CNYAUD", "alert": "falling", seconds: 3450 }

Build and Execution

To build the application:

./gradlew clean build

To run the application:

./gradlew run --args example/input1.jsonl

Submissions

Submissions will be assessed on:

  • correctness
  • code structure
  • clean, readable code
  • performance