WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint.
Now, comiing to file generation, it is not clear what do you mean by that. Is that about wsdl file generation. If that is the case, the wsdl will get generated, once you create a service soap in pega and then use service package to get that wsdl.
Soap connector is used in pega, by importing the wsdl. For all the operation, we create a connect soap rule. request and response properties are created. XML stream rule and parse rule are generated for the interaction to and from connect rule.
Our project uses SOAP Connector Integration wizard (screenshots pasted) to consume a WSDL file (via URL) to auto generate rules. Once done, you can use Data Page or activity to invoke the connector rule to call a service.
If you are talking about generating a WSDL file from Pega, then Pega is acting as a service provider (not a service consumer as explained above). A WSDL file can be generated in Pega using a service package.