Research And Implement Of Middleware Adaptive Mechanism Based On Microkernel Architecture

Middleware is an important infrastructure in pervasive computing environment. With the characteristic of ubiquity, dynamics and openness, pervasive computing requires middleware to be able to adapt to the environment changes. However, there are three remarkable defects in adaptive mechanism of existed middleware. First, most of adaptation models are at a lower abstract level for being closely related to the implement methods or application fields. Second, it is difficult to extend the middleware architecture to fulfill the rapid-growing application requirements. Third, the implement of adaptation logics are scattered throughout the business code, resulting in the tangled adaptation logic code that is difficult to understand, maintain and reuse.Microkernel technology is an architecture design pattern which emphasizes adaptability and extensibility. Based on microkernel pattern, this thesis proposes a pervasive middleware adaptation model by utilizing component, computational reflection and aspect-separation concept. By formalizing this model with first-order logic, this thesis gives a formal specification of middleware adaptation mechanism systematically. Based on this model, this thesis designs and implements an adaptive middleware kernel which realizes the objective of middleware adaptability and extensibility by using component to encapsulate middleware services and adaptive logics, and using event-driven engine to carry out adaptive behavior.The content of this thesis can be generalized as follows:First, this thesis studies the principles and key technologies of adaptive middleware, analyzes and compares several typical projects, then chooses microkernel technology as the architecture foundation of middleware adaptive mechanism and does research on its essence and applications.Second, this thesis presents Microkernel based Middleware Adaptation Model (MMAM). The model divides the middleware structure into components and connectors and uses aspect-oriented technology to encapsulate adaptation logic. The middleware adaptive behavior is driven by kernel introspection and event interaction mechanism. The model uses first-order temporal logic to formalize adaptive entities, adaptive behavior and reusable adaptation logic.Third, based on MMAM, this thesis designs Microkernel based Adaptive Middleware Kernel (MAMK). On the one hand, middleware services are encapsulated by MAMK Service Component to enhance middleware extensibility and adaptability. On the other hand, MAMK Event-Driven Engine drives the adaptive-aspect component to carry out middleware adaptive behaviors with the help of kernel introspection mechanism.Finally, this thesis implements MAMK prototype and does an experiment with actual scenes for validation. The experiment result turns out that MAMK is good at extensibility, and can dynamically adjust and configure middleware with the changes of environment.