普适计算环境的多样性、动态性和自主性对服务发现协议的适应性提出更高要求.传统服务发现协议中1)角色系统施加于设备的固定的功能集合和封闭的交互规则,以及2)对底层网络特性的两难假设阻碍了服务发现协议对环境中多样和动态的设备能力、连接方式和用户意图的适应;3)源自用户的自主性使得设备缺乏维护协议中交互规则的内在动机.提出基于能力(Ability)和策略(Policy)驱动的AP模型解决第一个问题;引入虚拟网络(Virtual Network)和组(Group)机制解决第二个问题,得到可适应的VGAP框架;基于市场机制建立Market模型解决VGAP中策略的自动选择这一分布式约束优化问题及第三个问题,得到自适应的服务发现模式VGMAP.原型系统和定量实验验证了VGMAP模式的自适应性.
The diversity and dynamics of pervasive computing environment(PvCE) demand the adaptability of service discovery in pervasive computing(PvC),and the autonomy of PvCE challenges the construction of the service discovery protocol(SDP).In traditional service discovery protocols 1) the fixed function set and the closed interaction rule set that the roles in SDPs impose on the devices,and 2) the dilemma of assuming underlying network features hinder them to obtain more adaptability.3) the devices′ autonomy from their users make them lack of motivation to follow the rules defined by SDPs.This paper propoes an Ability-based and Policy-driven model to address the first problem,introduces the Virtual network and Group mechanism to solve the second problem and to extend the AP model to an adaptive VGAP framework for service discovery,establishes the economic market based Market model to automatically select policies in VGAP and to make up for the lack of the motivation.Applying the Market model to the VGAP framework,this paper presents a self-adaptive service discovery schema VGMAP.The prototype system and simulation experiments verify the adaptability of the VGMAP schema.