1. In a distributed object application builder apparatus having a graphical user interface in which objects having plugs and sockets are interconnected to define distributed object application programs, a computer-implemented method of determining the plugs of a first object using said graphical user interface, said method comprising: identifying the first object by performing a selection action on the first object, said first object being represented by a graphical representation in said graphical user interface; retrieving an interface from a distributed object interface repository (IFR) that corresponds to the first object; determining at least one attribute from the retrieved interface, each determined attribute having an associated attribute type; determining at least one operation from the retrieved interface, each determined operation having an associated operation type; and indicating visually that said at least one attribute and said at least one operation are the determined plugs of the first object.