Ok - I will add in a little entry field and explanatory message box when I move up to this version.
OpenExchangeRates has 161 rates available so it is hardly any hassle for what you get.
Also, the 'best' polling time varies from exchange to exchange. For instance OpenExchangeRates updates hourly and with 1000 free polls per month it is pointless to poll faster than that.
Is that available on the exchange metadata or will I have to hardcode it ?
Hi Jim,
You can call getRefreshRate() on any exchange that implements CachedDataSession, such as OpenExchangeRates exchange, and it will give you the time in seconds representing the refresh rate for that particular data provider. CachedDataSessions cache the data internally as well, and make sure to only call out for new data at an appropriate interval. Another example of this is bitcoincharts. The refresh rate for that one is 15 minutes.
I hope that helps!