A method for developing an automation client program in a graphical programming environment is disclosed. The graphical programming environment provides a set of automation nodes and controls which may be dropped and wired together to create a graphical program. The nodes include an automation refnum which references a user-selected automation class from an automation type library; an automation open node which instantiates an object from the selected automation class; an automation invoke node which invokes a user-selected method of the automation class; and an automation property node which invokes, i.e., reads or writes, user-selected properties of the automation class. The nodes enable the displaying, manipulating, cataloging, editing or performance other operations, such as may be performed by an automation server, on data acquired or generated by a virtual instrument. A method for performing class propagation and type propagation checking of automation objects in a graphical program is also disclosed.