I suppose it could be as long as your publishable document looks just like the input document to the adapter service. Using a flow service as the target gives you a lot more flexibility though.
pub.flow:tracePipeline writes the pipeline to the server log. Is this what you want or do you really want to write it to standard out?
If service B doesn’t catch the exception, then the exception will automatically roll up to service A. This is why having the try-catch block only in the top-level service is often sufficient.
Typically, you would create a Flow to add things like error handling, retries, etc. to a basic adapter service and expose that as a web service.
“webMethods” is a company. Its message infrastructure product is webMethod Broker. Broker can be used by standalone apps that you write or by webMethods Integration Server.
See the SOAP / WSDL forum here for lots of pre-IS 7.1 examples. IS 7.1 changed how this is done to reduce the work required to use the interoperable document/literal style of SOAP messaging.
Web services support was greatly enhanced in IS 7.1 and, as a result, is very different from earlier releases. See the 7.1 version of the Web Services Developer’s Guide for details.