CORBA in real-time settings: a problem from the manufacturing domain

The Object Management Group's (OMG) Common Object Request Broker Architecture (CORBA) is an important and popular technology that supports the development of object based, distributed applications. The benefits promised by CORBA (abstraction, heterogeneity, etc.) are appealing in many application domains, including those that satisfy real time requirements-such as manufacturing. Unfortunately, CORBA was not specified in light of real time requirements, and so the question remains whether existing object request brokers (ORBs) can be used in real time settings, or whether developers of real time systems must await future extensions of CORBA that address real time issues or use non CORBA compliant ORBs. We describe the application of an off the shelf ORB in a real time manufacturing system developed at National institute of Standards and Technology (NIST) and tools which have been developed at the SEI for the analysis of CORBA's impact on the behavior of the system. Based on our experiences, we believe that today's ORBs can be used in real time settings, with certain caveats as outlined in the article. We also outline the concept of "composite objects", an approach for extending the range of non real time ORBs into a greater variety of real time settings.