In PowerDesigner, web services are made of web operations which themselves contain web parameters and result columns:
These objects have no symbols, but they appear in the Browser tree view.
This structure is compatible with the definition of web services in the supported databases.
You can import a web service as a service provider into a Business Process Model (BPM) to define the links between a concrete implementation of service interfaces and operations and their abstract definition.
For more information, see Business Process Modeling > Building BPMs > Business Process Diagrams > Service Providers (BPM).