Method and apparatus for determining the type of an object in a

Abstract

A method of checking the type of an object located on a remote computer in a distributed object environment computing system is disclosed. Initially, a type checking method to determine whether a remotely located object is of a specified type is invoked. In the invocation, a target interface identifier is included as an argument. A determination is then made as to whether the target interface identifier is equal to or a base for an apparent interface identifier held by a proxy object located on the first computer. If the target interface identifier is determined to be equal to or a base for the apparent interface identifier, an affirmative indication to that effect is returned to the client process. If not, then the target interface identifier is then compared to a real interface identifier. In many embodiments, a call to the server host will have to be made in order to determine the real interface identifier. In some embodiments, a local cache memory can also be provided to store the results of such inquiries. The target interface identifier is then compared to the real interface identifier and a determination is made as to whether the target interface identifier is equal to or a base for the real interface identifier. The result is then returned to the client process. A method of checking the type of an object and additionally returning an output proxy object is also disclosed. The output proxy object may be the original input proxy object that has been widened to the class associated with the target interface identifier, or may be a newly created proxy object that is of the same kind as the input proxy and of the same type as the target interface identifier.