Taverna can invoke many kinds of services, so there are many ways of producing them.
If you are a biologist/bioinformatician with many legacy command-line applications and you want to wrap them as Web services, we recommend Soaplab.
Soaplab is based on Perl. If you have more experience with Java, you might want to create services using Apache CXF. Also see the documentation for Web service developers.
Alternatively, you may expose your services through a REST interface.
