paysuper-currencies

README

Paysuper currency rates

This service is designed to synchronize currencies rates and to store it locally with a history of changes.

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Features

• Importing "OXR" and central banks currency rates.
• Calculating stock rates.
• Storing a rates' history of changes.

Table of Contents

• Developing
  • Branches
  • Start the application
  • Environment variables
  • Correction rules
  • Exchange directions
  • Storing
• Contributing
• License

Developing

Branches

We use the GitFlow as a branching model for Git.

Start the application

Application can be started in two modes:

• microservice - to maintain rates requests from other components of the PaySuper system. This mode does not request any rates. To run application as microservice don't pass any flags to a command line.
• console mode - to retrieve new rates from a source that has been passed as a command-line argument. The console mode can be used with a cron schedule.

To start an application in a console mode you need to set a -source flag in a command line with one of the following values:

• oxr - to get the rates from openexchangerates.org.
• centralbanks - to get the rates from central banks (currently from cbr.ru and ecb.europa.eu).
• stock - to calculate the stock rates.

This is an example of a command that runs rates requests from openexchangerates.org and at the end exits the application:

paysuper-currencies.exe -source=oxr

Environment variables

Name	Required	Default	Description
OXR_APP_ID	true	1	API App id for openexchangerates.org
MONGO_DSN	true	-	MongoBD DSN connection string
MONGO_DIAL_TIMEOUT	-	10	MongoBD dial timeout in seconds
CENTRIFUGO_URL	-	http://127.0.0.1:8000	Centrifugo URL
CENTRIFUGO_SECRET	true	-	Centrifugo secret key
CENTRIFUGO_CHANNEL	-	paysuper:admin	Centrifugo channel name to send alert notifications to admins
METRICS_PORT	-	80	Port for metrics and health check

Correction rules

For a rate may be applied correction rules. The correction rules apply at the moment of a rate or exchange request processing.

The correction rules can be defined for:

• a combination of RateType, ExchangeDirection, Merchant,
• optionally, for some currencies' pair (or for all pairs by default).

The system correction can be defined for:

• a combination of RateType, ExchangeDirection,
• optionally, some currencies' pair (or for all pairs by default).

Exchange directions

There are two directions for exchange and rates requests: buy and sell. The direction affects the application of the correction rules for rates and exchanges.

• Exchange direction buy increases an exchange rate for a per cent determined in the corresponding correction rule and decreases a result amount.
• Exchange direction sell decreases an exchange rate for a per cent determined in the corresponding correction rule and increases a result amount.

Storing

Example of a currency rate stored in the PaySuper database:

{
  "_id": "5cc7030b68add4454016232d",
  "created_at": "2019-04-29T13:58:35.921Z",
  "create_date": "2019-04-29",
  "pair": "USDRUB",
  "rate": 64.679270801,
  "source": "OXR",
  "volume": 1
}

Attribute	Description
_id	The ID of a record.
created_at	The datetime of saving a currency rate to the PaySuper database.
create_date	The date of save currency rate to the PaySuper database. It's used for a fast grouping rates to get the first, the last, min and max values by days.
pair	The currency's pair.
rate	The currency's pair rate.
source	The code of a rates source.
volume	The volume of exchanges that has been made for this rate. Optional. Default value equals to 0.

Contributing, Feature Requests and Support

If you like this project then you can put a ⭐️ on it. It means a lot to us.

If you have an idea of how to improve PaySuper (or any of the product parts) or have general feedback, you're welcome to submit a feature request.

Chances are, you like what we have already but you may require a custom integration, a special license or something else big and specific to your needs. We're generally open to such conversations.

If you have a question and can't find the answer yourself, you can raise an issue and describe what exactly you're trying to do. We'll do our best to reply in a meaningful time.

We feel that a welcoming community is important and we ask that you follow PaySuper's Open Source Code of Conduct in all interactions with the community.

PaySuper welcomes contributions from anyone and everyone. Please refer to our contribution guide to learn more.

License

The project is available as open source under the terms of the GPL v3 License.