Description

"Price Tracker" is a Node.js app that can be used to obtain the rates of many different symbols at different exchanges. This includes normal currencies, crypto currencies, gold/silver prices, and so on.

It uses Redis to store data, and cheerio (server-side jQuery) for scraping.

Everything is accesible via both REST and WebSockets APIs.

The application can be accessed live at http://price-tracker.herokuapp.com/

REST API

Exchanges Collection

Get Exchanges

Returns the list of supported exchanges, and supported symbols in each exchange.

Request:

GET /api/v1/exchanges

Example:

$ curl http://localhost:5000/api/v1/exchanges
{
  "data": [
    {
      "exchange": "ambito",
      "symbols": [
        "USDARS",
        "USDARSB"
      ]
    },
    {
      "exchange": "kraken",
      "symbols": [
        "BTCUSD",
        "LTCUSD"
      ]
    },
    [...]
  ]
}

Symbols Collection

Get Symbols

Returns the list of supported symbols, and the exchanges that provide them.

Request:

GET /api/v1/symbols

Example:

$ curl http://localhost:5000/api/v1/exchanges
{
  "data": [
    {
      "symbol": "XAUUSD",
      "exchanges": [
        "bullionvault"
      ]
    },
    {
      "symbol": "USDARSB",
      "exchanges": [
        "ambito",
        "cronista"
      ]
    },
    {
      "symbol": "BTCUSD",
      "exchanges": [
        "kraken",
        "bitfinex",
        "bitstamp",
        "coinbase",
        "okcoin"
      ]
    },
    [...]
  ]
}

Get Symbol

Returns the information for this symbol in this particular exchange.

Request:

GET /api/v1/symbols/<symbol>/<exchange>

Fields:

exchange: Name of the exchange/source
symbol: Symbol name
bid: Best buy offer
ask: Best sell offer
updated_on: Date in which this information was retrieved from the exchange (it may have been retrieved recently but the data could still be old)
custom: Additional data, depending on symbol/exchange
- volume24: Total volume transacted in the last 24 hours
- high24: Highest sell value in the last 24 hours
- low24: Lowest sell value in the last 24 hours
- published_on: Date in which this information was published (this is the real date, but it's not always available)
stats: Additional info generated from historical data
- last_change: Date of last registered price change
- daily: Daily OHLC
  - date: Period starting date
  - bid:
    - open: Period opening bid price
    - high: Period highest bid price
    - low: Period lowest bid price
    - closing: Period closing bid price
  - ask:
    - open: Period opening ask price
    - high: Period highest ask price
    - low: Period lowest ask price
    - closing: Period closing ask price

Example 1:

$ curl http://localhost:5000/api/v1/symbols/BTCUSD/bitstamp
{
  "data": {
    "exchange": "bitstamp",
    "symbol": "BTCUSD",
    "bid": 248.15,
    "ask": 248.35,
    "updated_on": "2015-06-27T20:55:54.519Z",
    "custom": {},
    "stats": {
      "last_change": "2015-06-27T20:55:54.519Z",
      "daily": {
        "date": "2015-06-27T00:00:00.000Z",
        "bid": {
          "open": 242.98,
          "high": 249.18,
          "low": 242.36,
          "close": 248.15
        },
        "ask": {
          "open": 243.01,
          "high": 249.62,
          "low": 242.37,
          "close": 248.35
        }
      }
    }
  }
}

Example 2:

$ curl http://localhost:5000/api/v1/symbols/USDARSB/cronista
{
  "data": {
    "exchange": "cronista",
    "symbol": "USDARSB",
    "bid": 13.4,
    "ask": 13.6,
    "updated_on": "2015-06-27T20:56:14.129Z",
    "custom": {
      "published_on": "2015-06-25T03:00:00.000Z"
    },
    "stats": {
      "daily": {
        "date": "2015-06-27T00:00:00.000Z",
        "bid": {
          "open": 13.4,
          "high": 13.4,
          "low": 13.4,
          "close": 13.4
        },
        "ask": {
          "open": 13.6,
          "high": 13.6,
          "low": 13.6,
          "close": 13.6
        }
      }
    }
  }
}

Get Price Series

Returns all stored prices for this particular symbol in this exchange in the specified date range.

Request:

GET /api/v1/symbols/<symbol>/<exchange>/series?start=<start>&end=<end>

Fields:

exchange: Name of the exchange/source
symbol: Symbol name
series: List of elements with the following fields:
- date: Period start date
- bid: buy offers OHLC for this period
- ask: sell offers OHLC for this period

Example:

$ curl http://localhost:5000/api/v1/symbols/USDARSB/cronista/series
{
  "data": {
    "exchange": "cronista",
    "symbol": "USDARSB",
    "series": [
      {
        "date": "2015-06-17T00:00:00.000Z",
        "bid": {
          "open": 12.6,
          "high": 12.75,
          "low": 12.6,
          "close": 12.75
        },
        "ask": {
          "open": 12.8,
          "high": 12.95,
          "low": 12.8,
          "close": 12.95
        }
      },
      {
        "date": "2015-06-18T00:00:00.000Z",
        "bid": {
          "open": 12.75,
          "high": 12.78,
          "low": 12.75,
          "close": 12.78
        },
        "ask": {
          "open": 12.95,
          "high": 13.08,
          "low": 12.95,
          "close": 13.08
        }
      }
    ]
  }
}

WebSockets API

var ws = new WebSocket(host);

// Using plain objects:
ws.onopen = function (event) {
    ws.send('{
        "type": "ExchangesRequest",
        "request": {
            "options": {}
        }
    }');
    ws.send('{
        "type": "SymbolRequest",
        "request": {
            "symbol": "LTCUSD",
            "exchange": "kraken",
            "options": {}
        }
    }');
};

// Or, using classes:
ws.onopen = function (event) {
    ws.send((new ExchangesRequest()).toString());
    ws.send((new SymbolRequest("LTCUSD", "kraken")).toString());
};

ws.onmessage = function (event) {
    var object = JSON.parse(event.data);

    if (object.type == "Exchanges") {
        object.response.data.forEach(function(item) {
            item.symbols.forEach(function(symbol) {
                console.log("exchange:", item.exchange, "symbol:", symbol);
            });
        });
    } else if (object.type == "Symbol") {
        console.log("symbol:", object.response.data.symbol);
        console.log("exchange:", object.response.data.exchange);
        console.log("bid:", object.response.data.bid);
        console.log("ask:", object.response.data.ask);
    }
};

Using wscat:

$ wscat -c ws://localhost:5000
Connected (press CTRL+C to quit)
> {"type": "SubscribeRequest", "request": {"symbol": "BTCUSD", "exchange": "bitstamp", "options": {}}}
< {"type":"Symbol","response":{"data":{"exchange":"bitstamp","symbol":"BTCUSD","bid":9251.95,"ask":9256.49,"updated_on":"2020-05-23T02:25:05.187Z","custom":{},"stats":{"last_change":"2020-05-23T02:25:05.187Z","daily":{"date":"2020-05-23T00:00:00.000Z","bid":{"open":9164.45,"high":9270.33,"low":9164.45,"close":9251.95},"ask":{"open":9171.96,"high":9276.07,"low":9171.96,"close":9256.49}}}}}}
< {"type":"Symbol","response":{"data":{"exchange":"bitstamp","symbol":"BTCUSD","bid":9251.95,"ask":9256.48,"updated_on":"2020-05-23T02:25:07.101Z","custom":{},"stats":{"last_change":"2020-05-23T02:25:07.101Z","daily":{"date":"2020-05-23T00:00:00.000Z","bid":{"open":9164.45,"high":9270.33,"low":9164.45,"close":9251.95},"ask":{"open":9171.96,"high":9276.07,"low":9171.96,"close":9256.48}}}}}}

Running

Install node:

Ubuntu: $ sudo apt-get install npm
macOS: $ brew install node

Install dependencies:

$ npm install

Run Redis: install from source (https://redis.io/download) or run it inside a container:

$ docker run -d -p 6379:6379 redis

Start the server:

$ node server.js

The server will be ready to accept connections at http://localhost:5000. Try with:

$ curl http://localhost:5000/api/v1/symbols/BTCUSD/bitstamp

Quick local testing:

Use the util/run-plugin.js tool to import a plugin and run it to fetch all supported symbols:

$ cd util
$ node run-plugin.js ../app/plugins/Cronista.js
symbol: USDARSCL response: Symbol {...}
symbol: USDARSCL response: Symbol {...}
symbol: USDARSCL response: Symbol {...}

pablojorge/price-tracker

Description

REST API

Exchanges Collection

Get Exchanges

Symbols Collection

Get Symbols

Get Symbol

Get Price Series

WebSockets API

Running

Quick local testing: