For users’ convenience, we will try to make the more simple method using the

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6. Conclusion and future work

We have implemented the appointed file prefetching mechanism on multiple-application-server architecture model for the thin-client/server computing model denoted MAS TC/S, which targets on the application of thin-client/server computing model on wide area network. Appointed file prefetching language (AFPL) is provided to set the appointed file prefetching instruction. A user can use AFPL to select the required file as a file set from user’s home directory or from user’s past file access records provided by MAS TC/S. There are two ways to perform the prefetching instruction which sends the file request to the appointed prefetching activator, one is time prefetching, and the other is event prefetching. The former one is to do prefetching on specific times, like a daily work, a weekly work, or an occasional work; it also can cooperate with a schedule file defined in XML. The latter one is to do prefetching while specific events are triggered.

Our analyzing of experiments has shown that the time of remote file fetch reduced by 30% to 90% and the hit ratio increased by 6% to 18% in most cases. This result enables significantly greater improvements both in LAN and WAN. While the more exactly a user select prefetched files, s/he will get much better performance.

However, in some tests, the appointed file prefetching increases the time of remote file fetch instead because the cache is too small for saving the prefetched files for a time. If the prefetched files are replaced before they are actually accessed, the appointed files prefetching doesn’t work effectively. We intend to choose just prefetch some appropriate files from the user’s file set by combining with the automatic file prefetching mechanism. With analyzing the probability of the next accessed files, we can sort the order of the prefetched files and prefetch these files on more exact time.

For users’ convenience, we will try to make the more simple method using the

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AFPL, like a GUI. In our prototype, we implement the appointed prefetching

mechanism on the distributed file system, OpenAFS. With the popularity of Java, we

tend to implement AFPL on other distributed file systems, like NFS, GFS, to expand

the availability. The prefetching mechanism may consider using the block of files to

prefetch so that it will not take too much size of cache. We hope an improved and

expandable version be introduced in near future.