The DSKI is a pseudo-device driver which enables a NetSpec experiment, through the DSKI measurement daemon, to specify and collect a series of time-stamped operating system level events of interest which occur during the experiment [1]. This is particularly useful when considering interactions among the application, middleware, and operating system levels of the endsystem. The primary target platform for the DSKI is Linux, but we have also ported it to DEC UNIX, and as a pseudo-device driver it can be ported relatively easily to any version of UNIX. The DSKI supports a range of data collection options with differing in level of detail and overhead. One particularly powerful feature is the ability to associate and arbitrary tag with an event. For example, when the tag is a packet ID or buffer address this enables post processing to track the progress of specific messages through the protocol stack. In the CORBA context, post processing of the event stream shows the amount of time spent by messages in different portions of the operating system when making object request calls to and from the ORB. We are currently working to create a similar ability to create, configure, and process streams of events from the CORBA and application levels.