Research of the mobile-code-based file system for portable information device

While the mobile communication device is developing into the portable information device, it is necessary to design a distributed file-system in such a mobile environment. In order to do it, we must consider the relative shortage of the portable storage and low computation ability of a portable information device as well as unreliable and low-performance networks. By using mobile code technology, we separate a traditional file-system into two parts: one part, which includes the operations and some temporary files that need low computation ability, is implemented in the client, while the other part(lots operations and services need high computation) are carried out in the server At first, we define "mobile-file", which includes the "context" and the partition of a special file. Then by constructing an actual file-system in server, which integrates the file-systems of clients in the network, the paper shows how to implement a practical file system and its operations on "mobile-file" and files for a portal device. The file-system of a portal device is stored as a part of the file-system of a server as well as only several partitions of some files, which are used in the portal device(client), and their "context" are temporarily stored in the client. After a client has finished a partition, the corresponding file in the server is updated, and at the same time the present partition is changed to the next partition. At end of the paper, we provide some simulated experiment results briefly.