著者

Yasushi Negishi Kiyokuni Kawachiya Hiroki Murata Kazuya Tago

雑誌

情報処理学会論文誌 (ISSN:18827764)

巻号頁・発行日

vol.41, no.10, pp.2881-2894, 2000-10-15

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Progress in semiconductor technology has made it possible to buildsmall network clients compact enough to be embedded in credit cardsor wallets. These devices which have severely restricted computingresources are called ``micro-clients.'' We propose an approach forbuilding systems for micro-clients.The requirements of a system for micro-clients are as follows:(? 1? ) It must work with a small amount of memory and a low-power processor.(? 2? ) It must work even while the link is disconnected because of thehigh cost of communication.(? 3? ) It must work with low-quality communication links.We introduce a software system called Tuplink that meetsthese requirements. The Tuplink system on the client node manages acentral data pool to hold user and system information in anintegrated manner. The server node also has a data pool for eachclient and the contents of both pools are kept identical by meansof a communication network. This server-side data pool makes iteasier to build a system in which necessary functions are dividedbetween server and client nodes. One-to-one communication betweenclient and server is abstracted by a synchronization operationbetween the two pools in order to hide link management andcommunication timing from other subsystems. A communication protocolfor synchronization called the Tuplink protocol is used tosynchronize the two pools. Other subsystems such as the RPC file and database systems use the central data pool instead of their ownbuffers. The state of the communication link is hidden from othersubsystems. We call this the ``meta-middleware'' approach.The Tuplink system meets the above requirements as follows:(? 1? ) Use of the central data pool eliminates duplication of buffersamong subsystems and copying of data among buffers.(? 2? ) The system can operate while the link is disconnected byusing the central data pool as a data cache.(? 3? ) The synchronization protocol efficiently handles packet loss byusing the central data pool as a communication buffer.We have built systems based on the Tuplink model and applicationsfor them on several platforms including a smart phone Palm III and Windows CE?@. This paper discusses the approach and findings ofthe system implementation.