Need a starting point for Optum

[Dale S]

I would like to write an app that merges Medicare claim data from medicare.gov, and patient claims data from optum (UnitedHealthcare).  I realize that this may be way off target for this group, but I thought maybe someone here would just have an idea for how I could find some basic starting point code.

I have registered my application [ https://portal.flex.optum.com/ ] and they tell you to go to the API doc [ https://www.uhc.com/legal/interoperability-apis ], and they say it uses the FHIR standard for standard member data and uses OAuth 2.0 / Open ID Connect for authentication.  I've developed applications for Android and iPhone, but looking at that API doc, I don't know where to start.  I figured there must be some code in the public domain that just authenticates and gets a list of claims for the authenticated member, or something like that.  That would be enough to get me started.