Experimental Analysis of the Correlation of HTTP GET Invocations

In this paper we experimentally investigate if optimal retry times can be determined based on models that assume independence of successive tries. We do this using data obtained for HTTP GET. This data provides application-perceived timing characteristics for the various phases of web page download, including response times for TCP connection set-ups and individual object downloads. The data consists of pairs of consecutive downloads for over one thousand randomly chosen URLs. Our analysis shows that correlation exists for normally completed invocations, but is remarkably low for relatively slow downloads. This implies that for typical situations in which retries are applied, models relying on the independence assumption are appropriate.