Applying patterns to develop a pluggable protocols framework for ORB middleware

To be an effective platform for performance-sensitive applications, off-the-shelf CORBA middleware must preserve the communication-layer quality of service (QoS) properties of applications end-to-end. However, the standard CORBA GIOP/IIOP interoperability protocols are not well-suited for applications with stringent message footprint size, latency, and jitter requirements. It is essential, therefore, to develop standard pluggable protocols frameworks that allow custom messaging and transport protocols to be configured flexibly and used transparantly by applications. This chapter provides three contributions to the study of pluggable protocols frameworks for performance-sensitive CORBA middleware. First, we outline the key design challenges faced by pluggable protocols developers. Second, we describe how we resolved these challenges by developing a plug-gable protocols framework for TAO, which is our high-performance, real-time CORBA-compliant ORB. Third, we present the results of benchmarks that pinpoint the impact of TAO's pluggable protocols framework on its end-to-end efficiency and predictability. Our results demonstrate how the application of optimizations and patterns to CORBA middleware can yield both highly flexible/reusable designs and highly efficient/predictable implementations. These results illustrate that (1) CORBA middleware performance is largely an implementation detail and (2) the next generation of optimized, standards-based CORBA middleware can replace many ad hoc and proprietary solut