Ahstruct-Network QoS parameters experience great fluctuations during the execution of network applications. Especially in mobile and pervasive computing environments the variation becomes more serious. Applications need to adapt their functions to the changing network status. Moreover, an enhanced software platform is necessary to provide adaptive network management services to upper software components. This paper proposes CME, a niiddleware architecture for service adaptation based on network awareness. CME is structured as the software platform both to provide network awareness to applications and to manage network resources in an adaptive fashion. The overall architecture of CME framework is descried. Core components include connection monitor, policy manager and connection controller. Adaptation mechanisms are introduced in detail. 1. Network applications relay on the underlying conimunication infrastructure to provide access to remote scrvices and resources. Ideally these applications do not conccrii anything about the networks used and could only focus 011 the service f~unctionalities they provide, but in practice this can iievcr be true. Large variations i n network quality of service (00s) (e.g. bandwidth, latency, jitter, reliability) may occiir during the information exchange. Thc situation of variations in network QoS parameters becomes to be more serious when two concepts are taken into account, network convergence and mobile communications. All data networks are converging on IP transport and applications arc also transforming towards being IP-based. However the underlying medium and link accessing techniques can he greatly diverse, mobile or fixed, wireless or wired. The converged network also mixes different types of traffic, each with very different requirements. Mobile communications are mostly based on portable devices and wireless network connectivity. The end user's tcrniinal can be greatly varying i n terms of e.g. processing and storage capabilities, input and output capacities, energy consumption, and networking technologies. There are different wireless access technologies including e.g. WLAN, Bluetooth, GSM, CPRS, UMTS, etc. Wireless access networks greatly vary by nature, with regard to e.g. error rate, fading, interferencc, etc. User mobility leads to the continuous changing of location and environment, network operator and servicc provider, and access nerworks. Handoff is one main source of network variations in terms of packet delay and packet loss. As the new computing diagram for the next generation mobile computing, pervasive computing [ 1 ] introduces more variations to network performance where the conimunication technologies could be highly diverse and overlapping in a smart space. To specify, one user telminal may be equipped with multiple connectivity technologies ranging from wireless sensor network and short-range ad hoc connection up to local and wide range connections. Current QoS model [2] are mainly oriented totally towards low-level network parameters such as bandwidth, latency, and jitter, targeting to provide a transparent management on network transport systeni to upper applications. However in many cases the mechanisnis for this model such as resource reservation are neither sufficient nor even feasible. There is an increasing need for network application; to be aware of the variation in network performance and quality. Applications should be more intelligent in order to adapt to various network environments, e.g. the access technologies being used and the greatly changing network status. On the other hand despite the differences in the functionalities of the applications. the main networking services can still be abstracted to coninion and unified interfaces to be used by diverse applications. Adaptation functions need to be rationally distributed into both specific applications and a general system platform, and then implemented with distinct mechanisms. The paper presents CME (Connectivity Management Engine), a middleware architecture for adaptive applications based on network awareness. CME provides flexible network supports to adaptive network applications with a set of functions and interfaces. We describe the overall architecture of CME in this paper, with the emphasis on the methodology of how to make application and network management context aware and how to provide adaptive networking services to network-aware applications. The rest of the paper is organized as follows: Section If presents the overall architecture of CME. Section 111 discusses the context considered in CME and the methods of how to realize context awareness. In Section IV we discuss the realization of adaptive network supports and the utilization of them in the adaptation of application. Section V concludes the paper with a discussion of future work.
CME REF "Connectivity Management Engine" is an example of a middleware architecture for network aware adaptive applications.
CME: a middleware architecture for network-aware adaptive applications
14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003.
14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003.
Computer Science