To tell Woopra which file you would like to export, you simply send it the name of the log file. This is also the PST date of the log file having the format yyyy-MM-dd. Ex: 2015-02-01 is the log file for Feb 1st, 2015. Log files are rotated at midnight PST. It is a good practice to send an http HEAD request to the same endpoint to get the current log file name.
Each response will contain two headers:
X-Woopra-NextPos You can use these to programmatically determine what parameters to use for your next call so as to avoid any duplicate lines coming in.
If you are exporting today's file, you will definitely need to use the
pos key to ensure that you can get data starting at the correct cursor when you make the next call. Otherwise you could get duplicate or missed events.