Characterizing reference locality in the WWW

• Authors: Virgílio Almeida;Azer Bestavros;Mark Crovella;Adriana de Oliveira
• Venue: DIS '96 Proceedings of the fourth international conference on on Parallel and distributed information systems
• Year: 1996

In this paper we propose models for both temporal and spatial locality of reference in streams of request arriving at Web servers. We show that simple models based on document popularity alone are insufficient for capturing either temporal or spatial locality. Instead, we rely on an equivalent, but numerical, representation of a reference stream: a stack distance trace. We show that temporal locality can be characterized by the marginal distribution of the stack distance trace, and we propose models for typical distributions and compare their cache performance to our traces. We also show that spatial locality in a reference stream can be characterized using the notion of self-similarity. Self-similarity describes long-range correlations in the dataset, which is a property that previous researchers have found hard to incorporate into synthetic reference strings. We show that stack distance strings appear to be strongly self-similar, and we provide measurements of the degree of self-similarity in our traces. Finally, we discuss methods for generating synthetic Web traces that exhibit the properties of temporal and spatial locality that we measured in our data.