I am writing an integration with GP web services for the first time and I am comparing the Receivables Transaction eConnect XML node to the ReceivablesInvoice and ReceivablesDocument WS objects. I cannot find properties on the WS objects for entering cash, check, or credit amounts or their associated check number or credit card name, for example. Is web services simply a limited subset of functionality and this is an example of that? Or should I find these properties somewhere I am not looking?
Correct, in some ways GP Web Services is a limited subset of functionality available in eConnect. As you have found, it is not possible to apply cash receipts with GP Web Services while it is possible using eConnect.
Using eConnect instead is an option, but if you want to stick to a 100% solution using GP Web Services then it is possible to extend GP Web Services and add additional functionality where it is missing.