SOAP based Custom service to create SO

Hi All,

I am able to create SO using http://vishwad365fo.blogspot.com/2018/05/custom-service-to-create-sales-order.html through JSON endpoint but it fails when using the SOAP endpoint.

Can anyone tell me what changes are required for it to work from SOAP because as per my knowledge service logic should remain same only endpoints differe for JSON and SOAP respectively.