Request for advice: Webservice interface updating records

Question

A webservice I have to write has to offer clients the following functionality: - retrieve business objects with selection of fields and records (paging) - delete business objects - update business objects - insert business objects The webservice is actually just an interface to an underlying business objects model. I'd like your advice on the following: In what way does the client have to tell which fields in which records he wants to insert/update? For instance: the client wants to update record (business object) with id "12345" and fields "Name" and "address" with given data. Should he provide a string array with field names and an object array with field values? Or maybe an XML document containing data from several records? Which would you advise me? Thanks in advance!