This project has two main parts:
Part 1: WSDL
In this part, you should develop a Web service and set it as WSDL. It's exactly as the second homework.
More info here:
Part 2: BPEL
Once the WSDL part is done, what we have to do is invoke the services and do some easy operations. Using BPEL it allow us to synchronize the invocation (asynchronous mode or synchronous mode), analyze the result (with some "if", "bigger than", etc) and even using some time expressions as "if after 20s it doesn't respond, do this".
The parts are independents. That is, once the WSDL part is done, to use it in the BPEL part, you don't have to make any modification.
What I recommend is using the increasing way to do this project, combining the part 1 with the part 2. For example, at beginning, develop the authentication service in the WSDL, then test it on the BPEL. Once everything work fine, do the rest.