1. October 15, 2002MASCOTS 2002 1 WebTraff: A GUI for Web Proxy Cache Workload Modeling and Analysis Nayden Markatchev Carey Williamson Department of Computer Science University of Calgary

2. October 15, 2002MASCOTS 2002 2 Introduction What is WebTraff? - An extended and improved version of ProWGen (Proxy Workload Generator), including a GUI interface to a useful set of tools for Web traffic modeling and analysis Purpose: To facilitate the easy generation and analysis of controllable and representative workloads for Web caching simulations

3. October 15, 2002MASCOTS 2002 3 Talk Overview WebTraff General Information System Requirements, Data Formats, Assumptions, Inputs, Outputs, Usage Simple Demo Using WebTraff to generate and analyze a workload, plus Web proxy cache simulation Questions and Discussion

4. October 15, 2002MASCOTS 2002 4 System Requirements Software Requirements Unix based environment running X windows cc, gcc, g++, tcl 8.0 or newer, tk 8.0 or newer, wish, perl 5.0 or newer, gnuplot, gs Hardware Requirements 64 MB or more RAM 100 MB hard disk space (for storing long workload traces) Future Work: Port to Windows (volunteers?)

5. October 15, 2002MASCOTS 2002 5 Example of the Web Workload Trace Format Used in WebTraff

6. October 15, 2002MASCOTS 2002 6 Overview of WebTraff The WebTraff toolkit provides three main functions: Web workload trace generation Web workload trace analysis Web proxy cache simulation Graphs displayed in PostScript format

7. October 15, 2002MASCOTS 2002 7 WebTraff GUI Interface

8. October 15, 2002MASCOTS 2002 8 Web Workload Generation

9. October 15, 2002MASCOTS 2002 9 Web Workload Generation This portion of the tool provides a GUI to ProWGen [Busari/Williamson 2001] ProWGen models four key characteristics of Web proxy workloads. Zipf-like document popularity distribution High degree of “one-time” referencing Heavy-tailed file and transfer size distributions Temporal locality property in references

10. October 15, 2002MASCOTS 2002 10 Web Workload Generation (cont’d) Name of trace file being generated Sliding widgets for: Number of references (lines) in a workload file Number of distinct Web objects in workload Percentage of objects that are “one-timers” Slope of Zipf-like document popularity profile Slope of Pareto tail for document size distribution Degree of statistical correlation (if any) between size and popularity for Web objects

11. October 15, 2002MASCOTS 2002 11 Web Workload Generation (cont’d) The notion of “temporal locality” refers to temporal correlation in referencing behaviour (e.g., recent past good predictor of near future) Four models for referencing behaviour: Independent Reference Model (IRM) Static LRU Stack Model (SLRU) Dynamic LRU Stack Model (DLRU) New LRU Stack Model (NLRU)

12. October 15, 2002MASCOTS 2002 12 Web Workload Generation (cont’d) “Popularity Bias” parameter (hack!) This button was added to remedy a problem in earlier version of ProWGen, which tended to choose one-timers early in the trace and popular documents late in the trace Can now control this in workload generation Can visually check for stationarity of cache hit ratio during simulations

13. October 15, 2002MASCOTS 2002 13 Web Workload Analysis

14. October 15, 2002MASCOTS 2002 14 Web Workload Analysis Two main categories of analysis functions: Time series analysis (on the left) Web workload analysis (on the right) Radio buttons, slide bars and text boxes available to control plotting characteristics

15. October 15, 2002MASCOTS 2002 15 Requests per Interval (time series plot)

16. October 15, 2002MASCOTS 2002 16 Bytes per Interval (time series plot)

17. October 15, 2002MASCOTS 2002 17 Popularity Distribution plot

18. October 15, 2002MASCOTS 2002 18 Document Size Distribution (zoomed)

19. October 15, 2002MASCOTS 2002 19 Log-Log Complementary Distribution (LLCD) plot (size)

20. October 15, 2002MASCOTS 2002 20 LRU Stack Depth Analysis (time series plot)

21. October 15, 2002MASCOTS 2002 21 LRU Stack Depth Analysis (marginal distribution)

22. October 15, 2002MASCOTS 2002 22 Web Proxy Cache Simulation

23. October 15, 2002MASCOTS 2002 23 Web Proxy Cache Simulation Application-level caching simulation parameters Cache size Cache replacement policy Five replacement policies currently available Random replacement (RAND) First-In-First-Out (FIFO) Least-Recently-Used (LRU) (default setting) Least-Frequently-Used (LFU) Greedy-Dual-Size (GDS)

24. October 15, 2002MASCOTS 2002 24 DHR Results from “Run Sizes”

25. October 15, 2002MASCOTS 2002 25 DHR Results from “Run Policies”

26. October 15, 2002MASCOTS 2002 26 BHR Results from “Run Policies”

27. October 15, 2002MASCOTS 2002 27 Assessing Cache “Steady State”

28. October 15, 2002MASCOTS 2002 28 For More Information… WebTraff toolkit: http://www.cpsc.ucalgary.ca/~carey/software.htm “ProWGen: A Synthetic Workload Generation Tool for the Simulation Evaluation of Web Proxy Caches” Busari/Williamson, Computer Networks, Vol 38, No 6, June 2002 http://www.cpsc.ucalgary.ca/~carey/publications.htm Contact information: Email {carey,nayden}@cpsc.ucalgary.ca