Using cURL on a project to contact a webservice to pull in some data for use in the client's content management system.
Data isn't extremely large. Just pulling basic page content. Data is requested via a curl/rest call. One authentication step, followed by sending session key within the header for each subsequent call (for the life of the session).
The authentication usually works without a hitch. But when calling on the actual data, sometimes I'm getting the data, and other times, I'm just getting nothing. It works about 1/3 of the time.
I like to consider myself a fairly competent programmer, but I'm just having a mental block trying to look for whether the problem is on my end (client side) or theirs (server side). And from there, whether it might be more of a code thing or a communication thing. Where would you start looking for the source of the problem?