The Design and Performance of a Real-Time CORBA Scheduling Service

There is increasing demandto extend CORBA middleware to support applications with stringentquality of service (QoS) requirements. However, conventionalCORBA middleware does not define standard features to dynamicallyschedule operations for applications that possess deterministicreal-time requirements. This paper presents three contributionsto the study of real-time CORBA operation scheduling strategies.First, we document our evolution from static to dynamic schedulingfor applications with deterministic real-time requirements. Second,we describe the flexible scheduling service framework in ourreal-time CORBA implementation, TAO, which supports core schedulingstrategies efficiently. Third, we present results from empiricalbenchmarks that quantify the behavior of these scheduling strategiesand assess the overhead of dynamic scheduling in TAO. Our empiricalresults using TAO show that dynamic scheduling of CORBA operationscan be deterministic and can achieve acceptable latency for operations,even with moderate levels of queueing.