ASYNCHRONOUS COMPLETION TOKEN

		   An Object Behavioral Pattern for
		Efficient Asynchronous Event Handling

		 Timothy H. Harrison, Irfan Pyarali,
			and Douglas C. Schmidt

			harrison@cs.wustl.edu
			irfan@wuerl.wustl.edu
			 schmidt@cs.wustl.edu

		    Department of Computer Science
			Washington University
			   Campus Box 1045
			 One Brookings Drive
		    St. Louis, Missouri 63130-4899
			(TEL): (314) 935-7538
				   
			       ABSTRACT

Contemporary applications must respond to many types of events ranging
from user interface notifications to network messages.
Delay-sensitive applications, such as network management systems for
high-speed networks, often perform long-running operations
asynchronously to avoid blocking the processing of other pending
events.  When these asynchronous operations complete, applications may
need more information than is provided with the notification to
properly handle the event.  This paper describes the Asynchronous
Completion Token pattern, which allows applications to efficiently
associate state with the completion of asynchronous operations.