On these pages, you can find public REST services of Inventory Plugin for JIRA.
Below, you can find sample REST service calls via CURL
curl -D- -u user:password -X [GET|POST|PUT|DELETE] -H "Content-Type: application/json" http://path.to.jira.instance/rest/jip-api/1.0/[attribute|form|inventory][|/id|/list|/filter].json
OR just call REST services with another method with a request header "Authorization Basic Base64Encoded(user:password)"
e.g. :"Authorization Basic YWRtaW46YWRtaW4="