Network Status Observation for A Dynamic Object Relocation Protocol

Takashi Watanabe, Makoto Hara

Abstract: The mobile cache protocol (MCP) was proposed as a relocation protocol of a replicated object in a widely distributed object system. The MCP has four basic features: relocating a replicated object, two optimistic update methods, object reservation and object sharing. To calculate the relocation function, the MCP uses processing time of the object at a candidate site and predicted network delay between the client and the candidate. Thus, a client observes network status to eliminate the ambiguity. But the observation of the entire network may cause overhand and undesirable traffic. The paper proposes some solutions for the problem, i.e., collecting processing time information of the partial network and probing delay by a preceding ping. Though designed for a distributed object based system, the MCP also can be applied to dynamic web caching. Evaluation using DEC Web trace shows the effectiveness of these strategies.