Hiho 
i'm currently working with VCO and NSX for my bachelor thesis and have ran into some problems when trying to use the NSX api from a VCO workflow.
I'm using the embedded VCO that ships with VRA 6.2 and NSX 6.1.3, all living inside a Vcenter 5.5
I'm just getting started with this and for now i want to just create a workflow that makes a GET request to <nsx-manager-IP>/api/versions.
I do this using the VCO HTTP-REST workflows from vco library,
First i ran "add a REST host" and set the URL to <nsx-manager-IP> which succeeded
Then "Add a REST operation" with template URL /api/versions which also succeeds
To test this i ran "invoke a REST operation" and selected my newly created operation, this is where i run into a wall,
This workflow fails and throws the exception : Connection pool shut down (Workflow:Invoke a REST operation / REST call (item0)#6)
The thing is i'm having a really hard time figuring out what this error means, so any help with that would be really appreciated
Some more information:
I've tried to send the exact same request with postmaster and that returns the excpected answer so atleast by now i'm fairly certain the error has something to do with something inside VCO 
Also I've tried to write the adress to NSX manager both as FQDN and it's IP adress with no change
// Oscar