WADE系统的多级分布式对象命名体系的设计与实现

DESIGN AND IMPLEMENTATION OF A DISTRIBUTED OBJECT NAMING HIERARCHY FOR THE METASYSTEM WADE

ＷＡＤＥ是一个基于校园网络的面向对象的元计算系统，通过分布式对象模型实现广域异构资源的一致管理．提出了一种４级对象层次结构支持该模型的组织与实现．对象命名代理负责用户与系统的接口、映射用户对象标识符ＵＯＩＤ到系统对象标识符ＳＯＩＤ，对象通信代理为对象绑定通信地址，建立通信对象标识符ＣＯＩＤ，对象存储管理器则负责对象的惰性保存，并通过永久对象标识符ＰＯＩＤ识别惰性对象．ＷＡＤＥ采用了双Ｃａｃｈｅ缓冲机制，有利于提高对象的操作与通信性能．

WADE is an object-oriented metacomputing system developed by the authors on a networked campus. The WADE distributed object model (WDOM) provides dependable and consistent access to wide area resources with heterogeneity on WADE. WDOM is implemented using a four-level object naming hierarchy. Firstly, the user-level objects are mapped by object naming agents to system-level, unique, location-independent names called SOID. And then, if communication between hosts is essential, system-level objects will be bound to communication-level names called COID. Finally, objects in inert are stored into the persistent storage devices such as hard disks with object identifier named POID. The object names such as SOID and COID are cached in term of LRU strategy so that the efficiency of the object operations is improved. Some tests show that the object naming hierarchy can improve expansibility and efficiency of metasystems.