This is an extreme simple WS-Discovery hack for Java without any dependencies to discover Onvif device addresses and others on local networks. Looking around for WS-Discovery implementations I found java-ws-discovery and apache-cxf, please look there if you need fully equipped SOAP implementations. Please feel free to add notes, suggestions and whishes or devices not responding or small success notes: Yeah, device xy is responding. If your device is not detected, please send a network recording of your UDP traffic.
Please check my modifications to https://github.com/thhart/onvif-java-lib if you want to use it for Onvif management.
-- Thomas Hartwig, June 2015