Try out these hands on guides from Oracle Open World (2008) for Business Services.
The first two hands on lab exercises are publisher Business services. The first one will give you an experience of calling a Business function from the Business Service, and retrieving a value. Similarly, the second hands on lab exercise will give you an experience of performing a Table I/O, and an insert.
The Last hands on lab is specifically for Consumer Business service, where JDE is the consumer of a 3rd party business service. Consumer BSSV is particularly important to know, since in many JDE applications, we have requirements to show the current weather, get currency conversion rates as of the moment, get market/commodity rates etc.