The typical scenario, on which every tutorial and walkthrough seems to advise, is to create an External Content Type with ReadList, ReadItem, Create, Update methods and then create an External List to provide access to the underlying system. This is relatively simple to achieve.
I have a source system in which the ReadList operation isn't an option - instead a user will enter an identifier and I need to validate or query the source system for that identifier. This is simple to do outside of SharePoint, but I cannot find any guidance on doing this within SharePoint without creating an External List.
My workaround at the moment is to create an External List with a trivial ReadList method (returning an empty list). The list will be useless, but I expect I'll be able to query the list for a known identifier in order to execute the underlying query.
I don't like this approach because I have a useless list in my site. Is there a better way to do this? Can I query the External Content Type without having an External List? Should I continue with the workaround above?