Hi Diane,
As far as I know, currently the SOAP service is available for SharePoint Foundation 2010 and Office SharePoint Server 2010, while not for SharePoint Online.
As for your requirements, I would like to suggest you send feedback to our operation team. Your time and efforts will be highly appreciated.
For more information about the SOAP service, you can refer to:
Add a SOAP service as a data source
Thanks,
Cherry Wang