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.
+ +