Method and apparatus for executing code during method invocation

Abstract

One or more filters may be included in each object implementation in a CORBA distributed object system. Each CORBA server object maintains a registry of filters containing unique identifiers and specifications for each of the filters and the order in which the filters must be applied. The filters execute selected code either before or after the conventional marshaling and unmarshaling which take place during a method invocation in the system. The CORBA client object builds a filter registry, from information that it received from the server. Filters may also be present in the client side of the ORB in order to execute code before and after the marshaling and unmarshaling that takes place in the client side of the ORB and these latter filters are also included in the client filter registry. The client then uses its filter registry to invoke the filters during a subsequent method invocation. The client also receives a time stamp from the server to identify the current filter composition. In method invocations to the server, the client includes the value of the time stamp it received and the server returns an exception to the client if the time stamps do not match. In response to this exception, the client re-invokes the _retrieve_filters() method in order to obtain the most recent filter registry contents and time stamp from the server.