NOTE-WCA-19990319 24.4 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
   "http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<style type="text/css">
      .feedback {border: thin solid black; padding: 1ex; margin: 1em;
        background: #808080; color: white}
      .subtitle {text-align: center}
    
</style>
<title>Web Characterisation Activity - Status Report</title>
<link rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-NOTE.css"
type="text/css">
</head>
<body>

<div class="head">
<P><a href="http://www.w3.org/"><img border="0" alt="W3C"
height="48" width="72" src="/Icons/w3c_home"></a></P>

<h1 class="no-num no-toc">Web Characterization:</h1>
<h2 class="no-num no-toc">From working group to activity</h2>
<h3 class="no-num no-toc">W3C Note Mar 19 1999</h3>
<dl>
<dt>This version:</dt>
<dd>
<a href="http://www.w3.org/TR/1999/NOTE-WCA-19990319">http://www.w3.org/TR/1999/NOTE-WCA-19990319</a>
</dd>
<dt>Latest version:</dt>
<dd>
<a href="http://www.w3.org/TR/NOTE-WCA">http://www.w3.org/TR/NOTE-WCA</a>
</dd>
<dt>Editors:</dt>
<dd>
Jim Pitkow &lt;<a href="mailto:pitkow@parc.xerox.com">pitkow@parc.xerox.com</a>&gt;, Xerox PARC<br>
Johan Hjelm &lt;<a href="mailto:hjelm@w3.org">hjelm@w3.org</a>&gt;, W3C/Ericsson<br>
Henrik Frystyk Nielsen, &lt;<a href="mailto:frystyk@w3.org">frystyk@w3.org</a>&gt;, W3C
</dd>
</dl>
<p>
<small><a href="/Consortium/Legal/ipr-notice#Copyright">Copyright</a> &copy;
1998 <a href="http://www.w3.org/">W3C</a> (<a
href="http://www.lcs.mit.edu/">MIT</a>, <a
href="http://www.inria.fr/">INRIA</a>, <a
href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a
href="/Consortium/Legal/ipr-notice#Legal Disclaimer"> liability,</a> <a
href="/Consortium/Legal/ipr-notice#W3C       Trademarks"> trademark</a>, <a
href="/Consortium/Legal/copyright-documents"> document use</a> and <a
href="/Consortium/Legal/copyright-software"> software licensing</a> rules
apply. Your interactions with this site are in accordance with our <a
href="/Consortium/Legal/privacy-statement#Public">public</a> and <a
href="/Consortium/Legal/privacy-statement#Members"> Member</a> privacy
statements.</small></p>
</div>

<h2>Status of this document</h2>
<p>
This document is a W3C Note reporting on the results of the HTTP-NG Web
Characterization Group and the structure of the Web Characterization Activity.
The work which was part of the <a href="/Protocols/HTTP-NG/Activity">W3C
HTTP-NG Activity, phase I</a>, is now continued in the <a
href="http://www.w3.org/WCA/">Web Characterization Activity</a>.</p>
<p>
Review comments on this document should be sent to &lt;<a
href="mailto:www-wca@w3.org">www-wca@w3.org</a>> which is the <a
href="http://lists.w3.org/Archives/Public/www-wca/">archived</a> email list
for the <a href="/WCA/">Web Characterization Activity</a>. Information on how
to subscribe to public W3C email lists can be found at <a
href="http://www.w3.org/Mail/Lists">the subscription request page</a>.</p>
<p>
<em>This document is a NOTE made available by the W3C for discussion only.
This indicates no endorsement of its content, nor that the Consortium has, is,
or will be allocating any resources to the issues addressed by this
NOTE.</em></p>

<h2>Table of Content</h2>
<dl>
<dt><a href="#Abstract">Abstract</a></dt>
<dt><a href="#1">1. The HTTP-NG Web Characterization Group</a></dt>
<dd><dl>
<dt><a href="#11">1.1 Mission statement</a></dt>
<dt><a href="#112">1.2 Participants</a></dt>
<dt><a href="#12">1.3 Deliverables and Accomplishments</a></dt>
</dl>
</dd>
<dt><a href="#2">2. The Web Characterization Activity</a></dt>
<dd><dl>
<dt><a href="#21">2.1 The structure of the Activity</a></dt>
</dl>
</dd>
<dt><a href="#3">3. Example characterizations</a></dt>
<dd><dl>
<dt><a href="#4">3.1 The HTTP-NG testbed</a></dt>
</dl>
</dd>
<dt><a href="#31">4. WCG papers</a></dt>
<dt><a href="#5">5. Summary</a></dt>
</dl>

<h2><a name="Abstract">Abstract</a></h2>
<p>
This document describes the experiences and results that came out of the Web
Characterization Group as part of the W3C HTTP-NG Activity, and how that work
is now continued in the Web Characterization Activity.</p>
<p>
The HTTP-NG Working Group created a series of scenarios for the HTTP-NG
protocol design group, which were implemented in the scope of the HTTP-NG
testbed, and used to optimize its design.</p>
<p>
The WCA started in November 1998, and will bring that work model to a wider
audience.</p>

<h2><a name="1">1. Introduction</a></h2>
<p>
Web Characterization is concerned with looking at the overall patterns of Web
structure and usage by measuring such aspects as server access patterns, the
kind of data being accessed, bytes transferred, popularity of resources, etc.
By better understanding the dynamics of the Web and how it grows we believe
that W3C and the Web Community in general will be better suited to evolve the
Web and to ensure its long term interoperability and robustness.</p>
<p>
The purpose of the Activity is to define and implement a scalable mechanism
for gathering data, boiling it down and to presenting it in efficient ways to
content providers, service providers, user groups, researchers and technology
designers and other groups.</p>
<p>
The information used to characterize the Web is strictly concerned with
general patterns of Web usage and does not focus on specific users or Web
sites. The scope of this Activity is to characterize the Web as a distributed
system and not on an individual basis.</p>

<h3><a name="11">1.1 Mission Statement</a></h3>
<p>
The HTTP-NG Web Characterization Group was chartered in August 1997 as a part
of the HTTP-NG Activity. Its intent was to create a stable and comprehensive
platform of knowledge and analysis of the Web, to enable the protocol
designers to create a relevant and well-instructed solution. Previously,
analysis of user behavior on the Web has often been based on spurious data,
gathered in an ad-hoc manner. The HTTP-NG Web Characterization Group was an
attempt at rectifying this.</p>
<p>
It was set up to fulfill four primary goals:</p>
<ol>
<li>
To respond to the questions raised by the HTTP-NG Protocol Design Group
regarding current usage of the World Wide Web.
</li>
<li>
To design and develop representative scenarios for use in the HTTP-NG testbed.
</li>
<li>
To make recommendations to the Protocol Design Group in issues concerning Web
usage and characterization methods.
</li>
<li>
To devise a system and a methodology to make characterization of the Web
easier and more reliable in the future.
</li>
</ol>

<h3><a name="112">1.2 Participants</a></h3>
<p>
The group consisted of members from Boston Universities Ocean group, Harvard
Colleges Vino group, INRIA, Microsoft, Netscape, Virginia Techs Network
Resource Group, and Xerox Parcs Webology group. Jim Pitkow, Xerox Parc,
chaired the group.</p>

<h3><a name="12">1.3 Deliverables and Accomplishments</a></h3>
<p>
The HTTP-NG WCG has leveraged and helped focus existing research programs,
which the group considers one of its major accomplishments.</p>
<p>
During its charter, the group has responded to the questions of the HTTP-NG
Protocol Design Group. This has been influential in the design of the HTTP-NG
protocol. It has also created the HTTP-NG testbed, which operates by using
SURGE (Scalable URL Generator) from Boston University Ocean Group. Scenario
parameters derived from observed statistical regularities in the distribution
of file sizes, reading times, and other metrics, were&nbsp;used to simulate
client traffic in the testbed. SURGE used some aspects of Web traffic which
were not taken into account by then current traffic generators.</p>
<p>
</p>

<center>

<table border="1" cellspacing="0" align="center">
<tbody>
<tr>
<th>
Status
</th>
<th>
Date accomplished
</th>
<th>
Deliverable
</th>
</tr>
<tr>
<td>
Done
</td>
<td>
Oct. 2-3, 1997
</td>
<td>
First face-to-face meeting
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
Nov. 1, 1997
</td>
<td>
Identification of classification parameters for Web categorization
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
Dec. 8, 1997 &nbsp;
</td>
<td>
Plan for response to HTTP-NG Protocol Design Group questions
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
Dec. 31, 1997
</td>
<td>
Initial response to HTTP-NG PDG questions
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
Feb. 7, 1998
</td>
<td>
Final response to HTTP-NG PDG questions
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
March-April 1998
</td>
<td>
Trace analysis for scenario building, refined testbed software
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
April 24, 1998
</td>
<td>
Extended scenarios, refined testbed software
</td>
</tr>
<tr>
<td>
Moved to WCA
</td>
<td>

</td>
<td>
Definition of new log file format
</td>
</tr>
<tr>
<td>
Moved to WCA
</td>
<td>

</td>
<td>
Recommendations for automatic re-sampling
</td>
</tr>
<tr>
<td>
Done
</td>
<td>
June 24, 1998
</td>
<td>
Project evaluation
</td>
</tr>
</tbody>
</table>
</center>
<p>
The group has completed all the original requirements, with the exception of
the redesign of the Common Log File Format and the recommendations for
automatic re-sampling of the Web, which has been moved to the Web
Characterization Activity.</p>

<h2><a name="2">2. The Web Characterization Activity</a></h2>
<p>
The W3C Web Characterization Activity was started in November 1998 with a
workshop, gathering some 50 persons interested in the subject. Subsequently, a
working group and an interest group has been started.</p>
<p>
The purpose of the Activity is to define and implement a scalable mechanism
for gathering data, boiling it down and to presenting it in efficient ways to
content providers, service providers, user groups, researchers and technology
designers and other groups.</p>
<p>
The information used to characterize the Web is strictly concerned with
general patterns of Web usage and does not focus on specific users or Web
sites. The scope of this Activity is to characterize the Web as a distributed
system and not on an individual basis.</p>
<p>
The Web Characterization Group in the HTTP-NG Activity was a first phase in
this project. It was completed in August 1998, and phase 2 begun. Its focus is
to extend the Web Characterization work and to create an active knowledge base
containing up-to-date information about the Web by broaden the scope of Web
characterization, and providing information and test scenarios for the W3C
Membership and the Web community in general about the Web and its use, both
now and in the near future.</p>
<p>
An important result of WCG is the identification of the three key groups in
the characterization work and how they interact:</p>
<p style="text-align: center">
<img src="WCG-org" alt="WCA org chart"></p>

<h3>Bulk Data Providers</h3>
<p>
The Bulk Data Providers are typically server maintainers and ISPs providing
server and proxy logs but can also be backbone providers gathering information
directly from the Net or users running instrumented Web clients etc. Because
of privacy concerns and because of the sheer size of log files, it is often
preferred to have data providers running a set of characterization tools
locally so that only the boiled down data sets and profiles are released.</p>

<h3>The W3C Characterization Working Group</h3>
<p>
The WCG develops and maintains a set of characterization tools used by the
data providers and defines the mechanism for exchanging boiled down data sets
and profiles with the data providers in order to maintain confidentiality and
trust. The collected data sets are used to develop characterization models and
to provide characterization data to the third group, the reduced data
consumers.</p>

<h3>Reduced Data Consumers</h3>
<p>
The reduced data consumers use the profiles and data sets provided by the WCG
and provide feedback and new questions to be asked. Primary data consumers are
expected to be content providers, service providers, user groups, researchers
and technology designers.</p>

<h2><a name="21">2.1 The structure of the Activity</a></h2>
<p>
The format for this Activity is to let the interaction between the reduced
data consumers and bulk data providers take place through an Interest Group,
with a new Web Characterization Working Group (WCG) functioning as the
mediator, provider of analysis tools and disseminator of characterization
information.</p>

<h4>Web Characterization Interest Group</h4>
<p>
The role of the Interest Group is to be a discussion forum for bulk data
providers and reduced data consumers, and to provide requests and feedback to
the Working Group. It is expected that the tools and dissemination mechanism
produced by the Working Group will benefit from a feedback mechanism with its
immediate users, as well as their continuous review. All work will be
discussed on the Web Characterization Activity Forum.</p>
<p>
Participation in the Interest Group is open to everybody.</p>

<h4>Web Characterization Workshop</h4>
<p>
The Activity was kicked off by the Web Characterization Workshop, November 5,
1998 in Boston, MA, with the intent of bringing together both W3C Members and
Web characterization experts. As a results of the Workshop, the Interest Group
was formed, and several organizations who wanted to participate in the Working
Group were identified.</p>

<h4>Web Characterization Working Group</h4>
<p>
The WCG is intended to work using a request/response based model similar to
the one&nbsp; used in the HTTP-NG Activity. Requests will be formally issued
by the Interest Group and by W3C Activities and the WCG will respond with
realistic time lines for when and how results can be made available.</p>
<p>
The WCG will start its work by formally soliciting requests for
characterization data needed by other W3C Working Groups and Activities. The
solicitation process is intended to occur at six-month intervals, enough time
for the Working Group to understand and respond to the requests of the other
W3C Groups. Requests from the Interest Group will be dealt with on a case by
case basis. All work will be discussed on the Web Characterization Activity
Forum.</p>
<p>
The working group has the following participants:</p>
<p>
</p>

<table border="1" cellpadding="0" style="text-align: center">
<tbody>
<tr>
<th>
<b>Name</b>
</th>
<th>
<b>Affiliation</b>
</th>
<th>
<b>Function in the WCA</b>
</th>
</tr>
<tr>
<td>
Marc Abrams
</td>
<td>
Virginia tech
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Martin F. Arlitt
</td>
<td style="text-align: left">
HP Labs
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Paul Barford
</td>
<td>
Boston University
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Pei Cao
</td>
<td>
University of Wisconsin
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Anja Feldmann
</td>
<td>
AT&amp;T Research Labs
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Edward A. Fox
</td>
<td>
Virginia Tech
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Johan Hjelm
</td>
<td>
Ericsson/W3C
</td>
<td>
Interest Group Chair
</td>
</tr>
<tr>
<td>
Balachander Krishnamurthy
</td>
<td>
AT&amp;T Research Labs
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Jim Gettys
</td>
<td>
W3C/Compaq
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Joe Meadows
</td>
<td>
Boeing
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Henrik Frystyk Nielsen
</td>
<td>
W3C
</td>
<td>
W3C Staff Contact
</td>
</tr>
<tr>
<td>
Ed O'Neill
</td>
<td>
OCLC
</td>
<td>
 
</td>
</tr>
<tr>
<td>
Jim Pitkow
</td>
<td>
Xerox PARC
</td>
<td>
Working Group Chair
</td>
</tr>
</tbody>
</table>
<p>
Further information about the work in progress can be found at the <a
href="http://www.w3.org/WCA/">Web Characterization Activity Home Page</a></p>

<h2><a name="3">3. Example Characterizations</a></h2>
<p>
The following are examples of some of the findings of the HTTP-NG WCG and
other researchers in the field of Web Characterization. This is by no means
meant to be neither a complete listing of the findings of the HTTP-NG WCG, nor
a representative sample of research in the field. Rather it contains results
that the group found provocative and representative of the types of questions
the HTTP-NG WCG found to be of interest.</p>
<ul>
<li>
<b>Question:</b> Where do all the clicks go?
</li>
<li>
<b>Answer:</b> Analysis of performed independently by Alexa Internet and by
the HTTP-NG WCG analysis of AOL trace data indicates that only a few servers
account for the majority of all clicks issued by users. The proportions may
surprise you: 50% of the clicks go to only 1% of the WWW sites visited and 80%
of the clicks go to only 26% of the sites!
<p>
</p>
</li>
</ul>
<p align="center">
<img src="Links" alt="Links vs. Servers"><br>
<br>
<a href="http://www.alexa.com/">Alexa</a> Internet and WCG Analysis of AOL
Data - December 1997</p>
<ul>
<li>
<b>Question:</b> How fast is the Web growing?
</li>
<li>
<b>Answer:</b> Not as quickly as during the early years of the Web. Although
this calculation is a bit fuzzy given that the data sources used different
methods to count the total number of servers and definitions of what a server
actually is (virtual hosting, etc.), the rapid hyper-growth of the Web from
1992 to mid 1995 has slowed to roughly gaining an order of magnitude every 30
months
</li>
</ul>
<p>
&nbsp;</p>

<h2 align="center"><img src="Servers" alt="Number of Web Servers">
</h2>
<p align="center">
Source: <a href="/">W3C</a>, Mark Gray,
<a href="http://www.netcraft.co.uk/Survey/Reports/">Netcraft Server Survey</a></p>
<ul>
<li>
<b>Question:</b> How many WWW pages are there?
</li>
<li>
<b>Answer:</b> During the spring of 1998, two independent research groups (NEC
Research Institute and DEC Systems Research Center) employed the same
theoretical foundation of set intersection to answer this question, but came
up with different answers to the question! While the devil is in the details
of the methodology employed by each study, the general procedure was take
issue a set of queries to the major search engines and determine the number of
same pages returned by the engines. This tells us the number of pages that all
the search engines agree exist and the degree to which each search engine
contains pages the others do not. From this NEC reports that there are <a
href="http://www.neci.nj.nec.com/homepages/lawrence/websize.html">320 million
pages</a> while DEC reports that there are <a
href="http://www.research.digital.com/SRC/personal/Krishna_Bharat/WebArcheology/measurement.html">275
million pages</a>. Our analysis of the AOL log files point to approximately
200 - 250 million pages as of this writing.
</li>
<li>
<b>Question:</b> How often are broken links encountered? Redirections? POSTS?
GETs with appended content?
</li>
<li>
<b>Answer:</b> Primarily based on analysis of AOL data, we have found that the
number of broken links encountered while users surf the Web is between 5 and
8% of all clicks. The occurrence rate of redirections (when a site
automatically sends your request to another locations as often occurs with
advertising and legacy servers) is approximately 6 to 7% of the time. The HTTP
header POST only occurred 1% of the time whereas GET requests with appended
material occurred around 10% of the time. These headers are significant in
they are used to carry user data back to the server. This is useful for
searching, ordering, counters on pages that say how many times a page has been
visited, etc. Secure links (using SSL) occupies 152 000 out of 300 million
links (0.05%).
</li>
</ul>

<h3><a name="4">3.1 The HTTP-NG testbed</a></h3>
<p>
The HTTP-NG testbed was designed for the specific purpose of making reliable
and convincing claims that the performance of HTTP-NG would be comparable to
prior HTTP implementations. It was designed in close cooperation with the
HTTP-NG Protocol Design Group.</p>
<p>
An analysis of the current practice in load generation tools left the HTTP-NG
WCG concerned with the representativeness of the traffic being generated.</p>
<p>
Essentially, three types of traffic generation models exist: Stress testing,
trace replay, and statistically derived models. Many current traffic
generators follow the first model, by varying the number of requests per
second that are issued to the server. While this approach does test the
capacity of the server as measured by the number of HTTP operations per
second, it does not produce traffic patterns that have actually been
observed.</p>
<p>
The second model for traffic generation utilizes packet traces collected from
various servers and protocol analyzers. If this method had been used in the
test bed, the group would have had to acquire traces from representative
servers. Apart from determining what is representative, it also presents the
problem of which servers to include, and obtain permission to use their log
file information. Each Web site will also need to be recreated, due to e.g.
the effect of the file system configuration on performance.</p>
<p>
Consequently, the group selected to statistically model HTTP traffic. The
users were segmented into three strata: Corporate users, ISP users, and
educational users. To create models for the behavior of each strata, the group
obtained full log files from America Online (major ISP), AltaVista (search
engine/mixed user group), and Boston University (educational users). From
Microsoft (Corporate usage) a distribution of usage was obtained. All data
sets except for the AltaVista data were used to generate scenarios for the
testbed. The log file analysis tools used were based on the prior work of the
group members, and the personal connections of the group members were
instrumental in obtaining these data sets.</p>
<p>
The HTTP-NG testbed is designed as the diagram below shows:</p>
<p align="center">
<img alt="HTTP-NG testbed" src="http://www.w3.org/TR/NOTE-HTTP-NG-testbed/base"></p>
<p>
The HTTP-NG testbed was thus able to take both network characteristics and
user behavior into account, inserting a simulated network between the robot
simulating the client and the server. The statistical traffic generator takes
a set of parameters to create a mock server with the associated file system,
and a set of simulated clients that make statistically based requests for
files.</p>
<p>
The model characterizes sites as containing Web pages with embedded media and
Web pages without embedded media. Using a model that characterizes pages,
rather than just objects, makes alteration in the composition of sites easier.
This facilitates determining the effect of new technologies, like Cascading
Style Sheets (CSS).</p>

<h2><a name="31">4. WCG Papers</a></h2>
<p>
Throughout the year of the WCG's existence, various group members have
contributed papers, articles, and presentations to the group and the Web
characterization community. Given the limited focus of the HTTP-NG project
effort, it is not surprising that these items are focused on characterizations
and representative testbed designs.</p>
<p>
</p>

<center>

<table border="1" cellspacing="0" align="center">
<tbody>
<tr>
<th>
Author(s)
</th>
<th>
Papers, Articles, Notes
</th>
<th align="center">
Date Published
</th>
</tr>
<tr>
<td>
Jim Pitkow
</td>
<td>
<a href="http://www.w3.org/TR/NOTE-WCA">W3C Note: HTTP-NG WCG Status
Report</a>
</td>
<td>
July 1998
</td>
</tr>
<tr>
<td>
Jim Pitkow
</td>
<td>
<a
href="http://www7.scu.edu.au/programme/fullpapers/1877/com1877.htm">Summary
of WWW Characterizations<br>
</a>Paper at WWW7&nbsp;
</td>
<td>
April 1998
</td>
</tr>
<tr>
<td>
Huberman, Pirolli, Pitkow and Lukose
</td>
<td>
<a href="http://www.w3.org/Protocols/HTTP-NG/1998/02/1998-02-surfing-final.pdf">Strong Regularities
in World Wide Web Surfing</a>(PDF format)
</td>
<td>
April, 1998
</td>
</tr>
<tr>
<td>
Barford and Crovella
</td>
<td>
<a href="http://www.cs.bu.edu/techreports/97-006-surge.ps.Z">Generating
Representative Web Workloads for Network and Server Performance
Evaluation</a>(Postscript format)
</td>
<td>
November, 1997
</td>
</tr>
<tr>
<td>
Manley, Courage and Seltzer
</td>
<td>
<a href="http://www.eecs.harvard.edu/~margo/papers/hbench-web.ps">A
Self-Scaling and Self-Configuring Benchmark for Web Servers</a>
</td>
<td>
November, 1997
</td>
</tr>
<tr>
<td>
Manley and Seltzer
</td>
<td>
<a href="http://www.eecs.harvard.edu/~vino/web/sits.97.html">Web Fact and
Fantasy</a>
</td>
<td>
October, 1997
</td>
</tr>
<tr>
<td>
Abdulla, Fox and Abrams
</td>
<td>
<a href="http://www.cs.vt.edu/~chitra/docs/97webnet/">Shared User Behavior on
the World Wide Web</a>
</td>
<td>
October, 1997
</td>
</tr>
</tbody>
</table>
</center>
<p>
</p>

<h2><a name="5">5. Summary</a></h2>
<p>
The group has achieved its objectives, creating feedback for the HTTP-NG
Protocol Design Group by answering the questions this group had about the Web,
and by creating the HTTP-NG testbed, which enabled the creation of an
optimized and efficient design of the next generation of the Hypertext
Transfer Protocol. The Web characterization work is now being continued in the
Web Characterization Activity.</p>
<p>
</p>
<hr>

<address>
Jim Pitkow, Xerox PARC, Johan Hjelm, Ericsson/W3C, Henrik Frystyk Nielsen
W3C,<br>
@(#) $Id: NOTE-HTTP-NG-WCG-19990104.html,v 1.11 1999/01/04 23:06:42 frystyk
Exp $ </address>
</body>
</html>