An Efficient Component Model for the Construction of Adaptive Middleware

Abstract

Abstract. Middleware has emerged as an important architectural component in modern distributed systems. Most recently, industry has witnessed the emergence of component-based middleware platforms, such as Enterprise JavaBeans and the CORBA Component Model, aimed at supporting third party development, configuration and subsequent deployment of software. The goal of our research is to extend this work in order to exploit the benefits of componentbased approaches within the middleware platform as well as on top of the platform, the result being more configurable and reconfigurable middleware technologies. This is achieved through a marriage of components with reflection, the latter providing the necessary levels of openness to access the underlying component infrastructure. More specifically, the paper describes in detail the OpenCOM component model, a lightweight and efficient component model based on COM. The paper also describes how OpenCOM can be used to construct a full middleware platform, and also investigates the performance of both OpenCOM and this resultant platform. The main overall contribution of the paper is to demonstrate that flexible middleware technologies can be developed without an adverse effect on the performance of resultant systems.

The JBoss Extensible Server

“…OpenCOM [4] is a lightweight component model upon which an adaptive ORB has been implemented. As an in-process model built atop a subset of Microsoft's COM, OpenCOM appears more suitable for very fine-grained components than the JBoss service component model.…”

“…Some of these models, which bear less similarity with the JBoss/JMX model than Yasmin and OpenCOM, are discussed in [4].…”

“…Researchers have presented compelling arguments for also exploiting these techniques within the middleware platform [4,17]. We claim that application servers themselves can (and should) be built in a component-based way, out of dynamically deployable components that provide middleware services to application components.…”

Structuring reflective middleware using meta-information management: the Meta-ORB approach and prototypes

“…This proxy is created by the capsule manager at the same time as the capsule itself, by using a well-known configuration service (ConfigServer). 2 Communication between clients and the proxy can be either through HTTP (in the case of J2ME clients) or object requests (in the case of J2SE clients). Communication between the proxy and the target interface in the J2ME capsule is always based on HTTP, by superimposing an object request protocol on top of it.…”

“…In particular, the Open-COM runtime component model, together with the ReMMoC middleware built on top of it [15,2], strive for efficiency of implementation and memory footprint. This platform was written in C++, which, besides being an efficient compiled language, allows access to low-level features (such as virtual pointer tables), which greatly optimise performance.…”