Our team has more than 4+ years of working experience as a performance testers with loadrunner in field of Frontend as well as middleware. In past, we have also worked as contractor for a north american telecom company where we created a framework for API load testing with loadrunner which makes QA testers work easy. We have used web service, Http/HTML protocol in load runner.
We need to look at application design document(ADD) to know more about SOAP APIs. Afterwards, W need to check if client is having web service protocol license or not. If yes, we can use the same protocol to do the performance testing. If not, we can create a script with the help of HTTP/HTML protocol which can do the API level testing.
Please feel to contact us.