Publication No 36420

Author(s)

Scharf, M.*

Title

On the Response Time of Large-scale Composite Web Services

Methods

Performance Evaluation; Network Planning

Keywords

DISTRIBUTED DATABASE; END-TO-END DELAY; HEAVY TAIL; PERFORMANCE EVALUATION; QUEUEING THEORY; WEB SERVICES

Abstract

This paper studies the response time of a web service middleware that decomposes requests into sub-queries to different servers and then merges the results. We present a queuing model for such a fork-join system and an exact analysis for exponential server response times. We also provide accurate approximations for heavy-tailed server response times, which are a common effect in the Internet. Heavy-tailed distributions are critical since they may cause very long middleware response times, in particular in large-scale systems with many servers being involved. We show that in this case the performance can be significantly improved if the middleware does not have to wait for a few slow servers, i. e., if the merged result does not need to be absolutely complete. We discuss different choices to implement such a mechanism and quantify their impact on the middleware response time.

Year

2005

Reference entry

Scharf, M.
On the Response Time of Large-scale Composite Web Services
Proceedings of the 19th International Teletraffic Congress (ITC 19), Beijing, August 2005

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