QoS issues for wide-area CORBA-based object systems

CORBA is a distributed object technology which shows great promise in simplifying the task of programming applications which must operate over a wide area network (WAN). However, WAN environments are dynamic and hostile, making applications which are distributed over a WAN much more difficult to develop and maintain than those only distributed across a local area network (LAN). Quality of service (QoS) is a technology emerging in a number of communications substrates which needs to be provided at the object level to help distributed applications be easier to develop and be more adaptive at runtime. The paper describes some of the issues which CORBA based middleware must address to provide QoS for objects distributed across a WAN and overviews QuO, our middleware framework for wide area QoS