A Configurable CORBA Gateway for Providing Adaptable System Properties

Technologies for creating distributed object-oriented systems have evolved significantly over the last few years. While most early work focused on providing a functional abstraction (e.g., hiding specifics related to particular implementations of a function, or particular hardware or operating system characteristics), recent work has focused on providing higher-level, non-functional system properties, such as fault tolerance, intrusion tolerance, performance, timeliness, and consistency. Work in this area has varied widely with respect to the level at which the quality of service (QoS) is provided (e.g., network, operating system, middleware, or application) and the types of assurances that are provided to the user of the service. At the object level, one approach that has been used is to create a proxy, called a gateway, that masquerades as the remote object for which the quality of service is requested. The function of the gateway depends on the nature of the quality of service provided, as illustrated in the gateways presented in [Ami95], [Nah99], [Kal00], and [Sch01]. This paper describes an adaptable gateway that can provide a wide variety of quality-of-service properties through the creation of “handlers” that can be selected at run time. Currently available handlers provide fault tolerance, intrusion tolerance, and timeliness/consistency tradeoffs. Section 2 gives an overview of the gateway architecture. Section 3 details the different handlers that provide the mentioned properties and some combinations of the properties. Finally, Section 4 concludes the paper.