perfSONAR User Q&A and Other Discussion

[Mark Feit <>]

Dale W. Carder writes:

    Thus spake Mark Feit 
()
 on Fri, Mar 23, 2018 at 05:35:48PM +0000:
    > 
    > That shouldn’t cause any problems.  All of pScheduler’s interaction is 
based around URLs, which don’t have a way to specify protocol.  The way 
getaddrinfo() is configured on dual-stack systems will make the pSchedulers 
talk amongst themselves with IPv4 even if the tests specify IPv6.  
    
    I'm curious, what was the rationale in implementing the opposite of what
    is typically the default address selection order?

Sorry, I spake backwards.  The host names in pScheduler URLs are ultimately 
passed down to the system's getaddrinfo(), which will return IPv6 first if it 
makes sense to do so.  We use a Python library called Requests to handle all 
of the HTTP(S) work.

The negotiation process isn't tied to the test parameters other than in one 
spot where the test plugin gets asked to return a list of the participants' 
host names.  There's no protocol associated with those, so it's possible that 
negotiation for a test that specifies one protocol could be done with the 
other if things fall out the right way. 

--Mark