It would come as no surprise to anyone that I am interested in
-bitcoins and virtual currencies. I've been keeping an eye on virtual
-currencies for many years, and it is part of the reason a few months
-ago, I started writing a python library for collecting currency
-exchange rates and trade on virtual currency exchanges. I decided to
-name the end result valutakrambod, which perhaps can be translated to
-small currency shop.
-
-
The library uses the tornado python library to handle HTTP and
-websocket connections, and provide a asynchronous system for
-connecting to and tracking several services. The code is available
-from
-github.
-
-There are two example clients of the library. One is very simple and
-list every updated buy/sell price received from the various services.
-This code is started by running bin/btc-rates and call the client code
-in valutakrambod/client.py. The simple client look like this:
-
-
-import functools
-import tornado.ioloop
-import valutakrambod
-class SimpleClient(object):
- def __init__(self):
- self.services = []
- self.streams = []
- pass
- def newdata(self, service, pair, changed):
- print("%-15s %s-%s: %8.3f %8.3f" % (
- service.servicename(),
- pair[0],
- pair[1],
- service.rates[pair]['ask'],
- service.rates[pair]['bid'])
- )
- async def refresh(self, service):
- await service.fetchRates(service.wantedpairs)
- def run(self):
- self.ioloop = tornado.ioloop.IOLoop.current()
- self.services = valutakrambod.service.knownServices()
- for e in self.services:
- service = e()
- service.subscribe(self.newdata)
- stream = service.websocket()
- if stream:
- self.streams.append(stream)
- else:
- # Fetch information from non-streaming services immediately
- self.ioloop.call_later(len(self.services),
- functools.partial(self.refresh, service))
- # as well as regularly
- service.periodicUpdate(60)
- for stream in self.streams:
- stream.connect()
- try:
- self.ioloop.start()
- except KeyboardInterrupt:
- print("Interrupted by keyboard, closing all connections.")
- pass
- for stream in self.streams:
- stream.close()
-
-
-
The library client loops over all known "public" services,
-initialises it, subscribes to any updates from the service, checks and
-activates websocket streaming if the service provide it, and if no
-streaming is supported, fetches information from the service and sets
-up a periodic update every 60 seconds. The output from this client
-can look like this:
-
-
-Bl3p BTC-EUR: 5687.110 5653.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Hitbtc BTC-USD: 6594.560 6593.690
-Hitbtc BTC-USD: 6594.560 6593.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Hitbtc BTC-USD: 6594.570 6593.690
-Bitstamp EUR-USD: 1.159 1.154
-Hitbtc BTC-USD: 6594.570 6593.690
-Hitbtc BTC-USD: 6594.580 6593.690
-Hitbtc BTC-USD: 6594.580 6593.690
-Hitbtc BTC-USD: 6594.580 6593.690
-Bl3p BTC-EUR: 5687.110 5653.690
-Paymium BTC-EUR: 5680.000 5620.240
-
-
-
The exchange order book is tracked in addition to the best buy/sell
-price, for those that need to know the details.
-
-
The other example client is focusing on providing a curses view
-with updated buy/sell prices as soon as they are received from the
-services. This code is located in bin/btc-rates-curses and activated
-by using the '-c' argument. Without the argument the "curses" output
-is printed without using curses, which is useful for debugging. The
-curses view look like this:
-
-
- Name Pair Bid Ask Spr Ftcd Age
- BitcoinsNorway BTCEUR 5591.8400 5711.0800 2.1% 16 nan 60
- Bitfinex BTCEUR 5671.0000 5671.2000 0.0% 16 22 59
- Bitmynt BTCEUR 5580.8000 5807.5200 3.9% 16 41 60
- Bitpay BTCEUR 5663.2700 nan nan% 15 nan 60
- Bitstamp BTCEUR 5664.8400 5676.5300 0.2% 0 1 1
- Bl3p BTCEUR 5653.6900 5684.9400 0.5% 0 nan 19
- Coinbase BTCEUR 5600.8200 5714.9000 2.0% 15 nan nan
- Kraken BTCEUR 5670.1000 5670.2000 0.0% 14 17 60
- Paymium BTCEUR 5620.0600 5680.0000 1.1% 1 7515 nan
- BitcoinsNorway BTCNOK 52898.9700 54034.6100 2.1% 16 nan 60
- Bitmynt BTCNOK 52960.3200 54031.1900 2.0% 16 41 60
- Bitpay BTCNOK 53477.7833 nan nan% 16 nan 60
- Coinbase BTCNOK 52990.3500 54063.0600 2.0% 15 nan nan
- MiraiEx BTCNOK 52856.5300 54100.6000 2.3% 16 nan nan
- BitcoinsNorway BTCUSD 6495.5300 6631.5400 2.1% 16 nan 60
- Bitfinex BTCUSD 6590.6000 6590.7000 0.0% 16 23 57
- Bitpay BTCUSD 6564.1300 nan nan% 15 nan 60
- Bitstamp BTCUSD 6561.1400 6565.6200 0.1% 0 2 1
- Coinbase BTCUSD 6504.0600 6635.9700 2.0% 14 nan 117
- Gemini BTCUSD 6567.1300 6573.0700 0.1% 16 89 nan
- Hitbtc+BTCUSD 6592.6200 6594.2100 0.0% 0 0 0
- Kraken BTCUSD 6565.2000 6570.9000 0.1% 15 17 58
- Exchangerates EURNOK 9.4665 9.4665 0.0% 16 107789 nan
- Norgesbank EURNOK 9.4665 9.4665 0.0% 16 107789 nan
- Bitstamp EURUSD 1.1537 1.1593 0.5% 4 5 1
- Exchangerates EURUSD 1.1576 1.1576 0.0% 16 107789 nan
- BitcoinsNorway LTCEUR 1.0000 49.0000 98.0% 16 nan nan
- BitcoinsNorway LTCNOK 492.4800 503.7500 2.2% 16 nan 60
- BitcoinsNorway LTCUSD 1.0221 49.0000 97.9% 15 nan nan
- Norgesbank USDNOK 8.1777 8.1777 0.0% 16 107789 nan
-
-
-
The code for this client is too complex for a simple blog post, so
-you will have to check out the git repository to figure out how it
-work. What I can tell is how the three last numbers on each line
-should be interpreted. The first is how many seconds ago information
-was received from the service. The second is how long ago, according
-to the service, the provided information was updated. The last is an
-estimate on how often the buy/sell values change.
-
-
If you find this library useful, or would like to improve it, I
-would love to hear from you. Note that for some of the services I've
-implemented a trading API. It might be the topic of a future blog
-post.
-
-
As usual, if you use Bitcoin and want to show your support of my
-activities, please send Bitcoin donations to my address
-15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.
-
