coding exercise

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.

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

Cleanup

execute

./gradlew clean

to remove build artefacts prior to creating the archive file.