The tutorial/ExternalServices folder in the project contains the implementation of the external third-party services used in this tutorial. Normally, external services are implemented by some third-party and invoked over the internet by way of the SOAP protocol. However, because this tutorial is self-contained, the external services are implemented and stored in the tutorial project.
Changing the Partner Bindings describes how to change the partner bindings of the tutorial and run the tutorial with each partner service.