Temporal Spread In Archived Composite Resources (work in progress)

TEMPORAL SPREAD IN ARCHIVEDCOMPOSITE RESOURCES(WORK IN PROGRESS) SCOTT G. AINSWORTHMICHAEL L. NELSONOLD DOMINION UNIVERSITYCOMPUTER SCIENCE

WADL 2013JULY 25–26, 2013

INDIANAPOLIS, INDIANA USA

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CONTENTS

Motivation Related work Preliminary work Temporal Spread Future work Conclusion

7/26/13

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A FABLE FROM WAYBACK

7/26/13

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TEMPORAL SPREAD

7/26/13

2005-05-1401:36:08

+9 days

+18 days +18 days

+7 months

+2.1 years

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QUESTIONS• How much temporal spread exists in composite

mementos?• How can temporal spread be minimized?• What factors contribute, positively or negatively,

to spread?• Does combining multiple archives produce

better results?• Would users with differing goals benefit from

different minimization policies and heuristics?• How can temporal coherence be displayed to

users—simply?

7/26/13

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CONTENTS

Motivation Related work Preliminary work Temporal Spread Future work Conclusion

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RELATED WORKControl Crawl Data Quality, Future collections

• Spaniol et al. – crawling strategy • Denev et al. – change rates by MIME type and

depth• Ben Saad et al. – metadata from crawl used to

select best results from archive

Our Focus: Existing Data Quality• Existing collections• Datetime selection policies

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RELATED WORKUse Patterns

• AlNoamony et al. – Archive Access Patterns• Humans vs. Robots• Dip, dive, slide, & skim

Identifying Duplicates• Simple identity – images, other binary formats

• direct comparison• Hash comparison

• HTML, CSS (text)• Shingling, Jaccard distances, etc.• SimHash most promise ⃪

7/26/13

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RELATED WORK – MEMENTO*• HTTP extension for datetime negotiation

Request

Response

7/26/13

GET <timegate>/http://www.cs.odu.edu/ HTTP/1.1…Accept-Datetime: Sat, 10 May 2005 11:21:00 GMT…

HTTP/1.1 200 OK…Memento-Datetime: Sat, 14 May 2005 01:36:08 GMT…

*https://datatracker.ietf.org/doc/draft-vandesompel-memento/

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CONTENTS Motivation Related work Preliminary work

How much of the Web is archived Temporal Drift

Temporal Spread Future work Conclusion

7/26/13

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HOW MUCH IS ARCHIVED?

7/26/13

35 – 90% At least one archived copy17 – 49% 2 – 5 copies 1 – 8% 6 – 10 copies 8 – 63% > 10 copies JCDL’11

Internet Archive Search Engine Other

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CONTENTS Motivation Related work Preliminary work

How much of the Web is archived Temporal Drift

Temporal Spread Future work Conclusion

7/26/13

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TEMPORAL DRIFTComparing two policies

• Sliding –target datetime changes• Sticky – target datetime held steady

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SLIDING TARGET

7/26/13

2005-05-14 01:36:08

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SLIDING TARGET

7/26/13

2005-04-2200:17:52

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SLIDING TARGET

7/26/13

2005-03-3109:16:10

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TEMPORAL DRIFTWHAT WE EXPECTED2005-05-14 @ 01:36:08

WHAT WE GOT2005-03-31 @ 09:16:10

7/26/13

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STICKY TARGET

What if the target is held steady?

(Enabled by Memento API)

7/26/13

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2005-05-14STICKY TARGET

7/26/13

Mem

ento

Fox

Exte

nsio

n2005-05-14

01:36:08

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STICKY TARGET

7/26/13

2005-04-2200:17:52

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STICKY TARGET

7/26/13

2005-05-1401:36:08

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DRIFT COMPARISONPage

Sliding StickyDatetime Drift Datetime Drift

CS Home 2005-05-1401:36:08 – 2005-05-14

01:36:08 –

Science Home

2005-04-2200:17:52 22.1 days 2005-04-22

00:17:52 22.1 days

CS Home 2005-03-3109:16:10

43.7 days(+21.6 days)

2005-05-1401:36:08 –

Mean 32.9 days 11.0 days

7/26/13

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MEDIAN DRIFT BY STEP

● Sliding● Sticky

Med

ian

Drif

t (m

onth

s)

7/26/13

Step Number

JCDL’13

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CONTENTS Motivation Related work Preliminary work

How much of the Web is archived Temporal Drift

Temporal Spread Future work Conclusion

7/26/13

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TEMPORAL SPREAD

7/26/13

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COMPOSITE MEMENTOPRESENTATION STRUCTURE

7/26/13

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TEMPORAL SPREAD

7/26/13

2005-05-1401:36:08

+9 days

+18 days +18 days

+7 months

+2.1 years

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EMBEDDED RESOURCESResource Memento-Datetime Delta Resource Memento-

Datetime Delta

http://www.cs.odu.edu 2005-05-14 01:36:08 spacer.gif 2005-06-01 16:23:10 18.6 d

mm_menu.js 2005-05-23 02:39:12 9.0 d jimcheng.gif 2005-06-01 16:37:39 18.6 d

style.css 2005-05-23 02:39:39 9.0 d jsmith.gif 2005-06-01 16:58:50 18.6 d

gfx-logo-odu-crown.gif 2005-05-23 02:39:39 9.0 d rmenu_1st_featured_alumni.png 2005-06-01 21:21:45 18.8 d

ddmenu_ddown.js 2005-05-23 02:39:43 9.0 d hmenu_college_...-new.png 2005-12-21 20:14:25 7.3 mo

university.js 2005-05-23 02:39:56 9.0 d rmenu_1st_upcoming_news.png 2005-12-21 20:15:14 7.3 mo

rmenu_1st_about.png 2005-06-01 13:40:25 18.5 d rmenu_1st_upcoming_events.png 2005-12-21 21:01:12 7.3 mo

rmenu_bottom_229.gif 2005-06-01 14:07:29 18.5 d lmenu_1st_resources.png 2005-12-28 17:47:41 7.5 mo

shadow-bl.gif 2005-06-01 14:55:53 18.6 d bullet_blue_triangle.gif 2005-12-28 19:43:48 7.5 mo

ecsbdg.jpg 2005-06-01 14:56:17 18.6 d logo-cs.gif 2005-12-28 19:54:29 7.5 mo

shadow-br.gif 2005-06-01 15:18:18 18.6 d rmenu_1st_featured_student.png 2007-06-12 02:36:07 2.1 years

gfx-btn-go-dblue.gif 2005-06-01 15:34:19 18.6 d shadow-b.gif 2007-06-21 02:35:17 2.1 years

shadow-tr.gif 2005-06-01 15:55:57 18.6 d shadow-r.gif 404 Not Found

header-right1.gif 2005-06-01 16:06:16 18.6 d

7/26/13

Embedded Resources 26

Mean Delta 125.9 days

Standard Deviation 207.7 days

Spread 2.1 years

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REPRESENTING SPREADCOMPOSITE MEMENTO

TEMPORAL SPREAD CHART

7/26/13

RootEmbeddedDiff. DomainReused

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TEMPORAL SPREAD – ODU CS

7/26/13

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FIRST EXPERIMENT

• 1,000 URIs from DMOZ (Open Directory)• Download all timemaps• Download all composite mementos• Download all embedded resources• Single and Multiple Archives• Four Heuristics

7/26/13

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PRELIMINARY RESULTSCount Description Percent

1,000 Root URI-Rs

910 Root timemaps 91%

87,847 Root URI-Ms in timemaps

96.5 URI-Ms per Root URI-R

85,570 Root memento downloaded 97%

1,488,420 Embedded URI-Rs

17.4 Embedded URI-Rs per Root memento

7/26/13

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SINGLE/MULTI & HEURISTICSDescription Minimize

Distance, Single

Archive

Minimize Distance,

Multi-Archive

3-Month Window,

Multi-Archive

Embedded URI-Rs 1,488,440 1,488,420 1,447,351

Embedded URI-Ms in timemaps 1,169,787 1,186,456 500,541

URI-M/Embedded URI-R 0.79 0.80 0.35

% Complete 73.8% 75.4% 33.8%

Mean spread 200.2 200.1 15.1

Standard Deviation 219.2 219.9 14.3

7/26/13

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TEMPORAL COHERENCE

7/26/13

1 Memento, Bracketed Root

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TEMPORAL COHERENCE

7/26/13

1 Memento, Bracketed Root

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TEMPORAL COHERENCE

7/26/13

1 Memento, Bracketed Root

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TEMPORAL COHERENCE

7/26/13

1 Memento, Root Not Bracketed

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TEMPORAL COHERENCE

7/26/13

1 Memento, Root Not Bracketed

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TEMPORAL COHERENCE

7/26/13

1 Memento, No Last-Modified

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TEMPORAL COHERENCE

7/26/13

1 Memento, Before Root

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TEMPORAL COHERENCE

7/26/13

2 Mementos, Root Not Bracketed

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TEMPORAL COHERENCE

7/26/13

2 Mementos, Root Not Bracketed

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TEMPORAL COHERENCE

7/26/13

2 Mementos, Use Content – Similarity

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TEMPORAL COHERENCE

7/26/13

2 Mementos, Contents Equal or Equivalent

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TEMPORAL COHERENCE

7/26/13

2 Mementos, Contents Not Equal or Equivalent

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CURRENT EXPERIMENT

• 4,000 URIs from JCDL’11 “How Much…” paper• 1 URI/month vice all• Temporal coherence patterns• Target WSDM 2013

7/26/13

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CURRENT EXPERIMENT

7/26/13

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CONTENTS Motivation Related work Preliminary work Temporal Spread Future work Conclusion

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FUTURE WORKTimemaps, Redirection, Missing Mementos• Timemaps only tell part of the story• URI-R redirection (302 from source)• URI-M redirection (Archive action)• Mementos in timemaps but not accessible• Policies must consider user needs

• Leave it missing• Show “best” substitute

7/26/13

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FUTURE WORKSimilarity & Duplication• Delta are currently | root – embedded |• If bracketing mementos are identical,

should delta be zero?

• HTML is usually modified by the archive• Can’t check for equality• Shingling? SimHash?

7/26/13

0 +30d–30d

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FUTURE WORKCommunicating Status

7/26/13

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FUTURE WORKPolicies & Heuristics• Current Spread Heuristics

• Minimize distance• Past only• Past preferred• Near or within distance• Single vs. multi-archive

• Refine to meet user expectations• Speed (minimize time)• Accuracy (minimize temporal error)

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CONTENTS

Motivation Related work Preliminary work Future work Conclusion

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CONCLUSIONExtensive research on improving acquisition exists

Best use of existing collections needs study

We are looking at

• Characterizing existing holdings

• Characterizing temporal coherence

• Policies that minimize impact of temporal incoherence

• Visualizations of temporal coherence

7/26/13

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MY QUESTIONS

7/26/13

Coherent

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MY QUESTIONS

7/26/13

Violation

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MY QUESTIONS

7/26/13

What do

these mean

to users?

(3)

(2)

(1)

(4)

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MY QUESTIONS

7/26/13

What does

this mean

to users?