Reducing delay with dynamic selection of compression formats

Abstract

Internet computing is facilitated by a remote execution methodology in which programs transfer to a destination for execution. Since the transfer time can substantially degrade the performance of remotely executed (mobile) programs, file compression is used to reduce the amount of data that is transferred. Compression techniques however, must trade off compression ratio for decompression time, due to the algorithmic complexity of the former, since the latter is performed at run-time in this environment. In this paper, we define the total delay as the time for both the transfer and the decompression of a compressed file. To minimize the total delay, a mobile program should be compressed in the best format for minimizing the delay. Since both the transfer time and the decompression time are dependent upon the current underlying resource performance, selection of the "best" format varies and no one compression format minimizes the total delay for all resource performance characteristics. We present a system called Dynamic Compression Format Selection (DCFS) for the automatic and dynamic selection of competitive compression formats based on the predicted values of future resource performance. Our results show that DCFS reduces the total delay imposed by the compressed transfer of Java archives (.jar files) by 52% on average for the networks, compression techniques and benchmarks studied.