Memento Update CNI Task Force Meeting, Spring 2011 1
Memento http://mementoweb.org/
Herbert Van de Sompel Robert Sanderson Michael L. Nelson
Big Leaps Towards Seamless Navigation of the Web of the Past
Memento Update CNI Task Force Meeting, Spring 2011 2
Overview of Memento Framework
Deployment Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
Memento Update CNI Task Force Meeting, Spring 2011 3
Overview of Memento Framework
Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
Memento Update CNI Task Force Meeting, Spring 2011 4
Memento wants to make it easy
to access the Web of the Past.
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Tate Online Today
Select Date March 16 2008
Tate Online March 16 2008
From National Archives
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Memento achieves this by introducing
a uniform version access capability to
integrate the present and past Web.
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Content Management Systems:
• Designed to be aware of all versions of a resource;
• Self-contained;
• Variety of proprietary version mechanisms;
• Versions interlinked using proprietary mechanisms.
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World Wide Web:
• Designed to forget about prior versions of a resource;
• Distributed.
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There are resource versions on the Web:
• Content Management Systems;
• Web Archives;
• Transactional archives;
• Search engine caches.
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But the Web architecture has a hard time dealing with them:
• Cannot talk about a resource as it used to exist;
• Cannot access a prior version knowing the current one;
• Cannot access the current version knowing a prior one;
Current approaches are ad hoc and localized.
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Memento:
• Regards the Web as a big Content Management System
• Introduces a uniform capability to access versions on the Web;
• Does not build new archives but leverages all systems that host versions: Web archives, Content Management Systems, Software Version Systems, etc.
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Memento’s version access approach:
• Is distributed: versions may exist on several servers;
• Uses time as a global version indicator;
• Is based on the primitives of the Web: resource, resource state, representation, content negotiation, link.
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Original Resource and Versions
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Bridge from Present to Past
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Bridge from Past to Present
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Memento Framework
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Multiple Archives
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Memento Client-Server Interaction
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Overview of Memento Framework
Deployment Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
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Significant progress has been made towards
seamless navigation of the Web of the Past.
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Standardization:
• Standardization process started via the IETF;
• Interest from IETF and W3C;
• Encouraged by major Web architects, including: Tim Berners-Lee, Mark Nottingham, Michael Hausenblas.
https://datatracker.ietf.org/doc/draft-vandesompel-memento/
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Memento Clients:
• Several client tools developed by us and others;
• Add-ons for FireFox (operational) and Internet Explorer (experimental);
• Applications for Android (operational) and iPhone/iPad (in development);
• Paper in next issue of Code4Lib Journal.
http://www.mementoweb.org/tools/
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Memento server support (1):
• Memento-compliant Wayback software:
• Used by Internet Archive.
• Available to Web archives, worldwide.
• Please have your favorite Web Archive install this new version 1.6!
http://www.mementoweb.org/tools/
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Memento server support (2):
• Plug-in for MediaWiki (operational);
• Used on W3C’s main wiki.
• Please install it for your MediaWiki!
http://www.mementoweb.org/tools/
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Memento Server Validator
• Server side client:
• Attempts to perform all Memento actions against a given URI
• Reports success/failure of the interactions and warnings for optional aspects
• Kept up to date with IETF Internet Draft
http://www.mementoweb.org/tools/
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Memento Proxy Support
• Several systems that host Mementos made Memento-compliant “by proxy”:
• All major Web Archives that do not yet run Memento-compliant Wayback software
• 3,000+ MediaWiki systems, including Wikipedia
• We want all of these to become natively Memento compliant!
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Memento Website:
• Ongoing effort to add materials that support understanding and adoption: • Introduction to Memento • How to recognize
Mementos, TimeGates, Original Resources?
• Guidelines for servers that host Mementos (Web Archives, CMS, snapshot archives, etc.)
http://www.mementoweb.org/guide/
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Funding:
• 2007-2010: US $250K grant from Library of Congress; • Approx. 50K on Memento.
• 2010-2011: US $1 Million follow-up grant from Library of Congress.
• For: Specification, outreach, tool development, further research.
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Overview of Memento Framework
Deployment Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
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Memento Time Travel is really powerful.
Time-Series Data via HTTP follow-your-nose.
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Memento Framework
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Original Resource: http://dbpedia.org/resource/France
Memento Framework & Time Series
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Time Travel across DBpedia Versions
Data collected through HTTP Navigation
paper at http://arxiv.org/abs/1003.3661
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Overview of Memento Framework
Deployment Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
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Very few Web sites provide a “timegate” link.
Need additional mechanisms to support Discovery.
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Batch discovery of Mementos: TimeMaps
A TimeMap minimally lists:
• URI and datetime of Mementos known to an archive • URI of Original Resource
TimeMaps can be aggregated across systems that host Mementos
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Batch discovery of Mementos: Feed of TimeMaps
• System that host Mementos exposes Feed (e.g. Atom) of TimeMaps to allow applications to remain in sync with its evolving Memento collection:
• One Atom entry per Original Resource for which system hosts Mementos; • The entry provides a “timemap” link to a TimeMap for the Original Resource; • The datetime value of the updated field of the entry changes when additional Memento for Original Resource becomes available (i.e. TimeMap changes); • The ID of the entry is a tag URI based on URI of Original Resource.
Will be proposed to IIPC
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Batch discovery of Mementos: robots.txt
• robots.txt file is used by Web servers to convey crawling policies;
• Add a directive to support discovery of Mementos known to the server:
• Pointer to a single Memento can suffice as the robot can crawl on from there • Mementos allow for discovery of TimeMaps via HTTP links. • e.g. jcdl.org hosts snapshot archives of prior JCDL conferences and adds the following to its robots.txt:
Memento: jcdl.org/archive/2002/index.html
Will be promoted via Internet Draft
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Batch discovery of TimeGates: robots.txt
• robots.txt file is used by Web servers to convey crawling policies;
• Add a directive to support discovery of TimeGates known to the server:
• TimeGates can be on server itself or on external server • Value for the directive is typcially a regular expression • e.g example.org could point at TimeGates in its associated transactional ta.org via robots.txt:
TimeGate: ta.org/timegate/http://example.org/*
Will be promoted via Internet Draft
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Discovery of Systems that Host Mementos: Registry/Feed
• Registry of collections of Mementos, e.g. of Web Archives, Transactional Archives, etc.
• Feed of registry records.
• A registry record details essential characteristics of a Memento collection.
• cf VOiD collection description for Linked Data.
Will be researched
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Overview of Memento Framework
Deployment Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
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Memento can recreate pages using resources from different archives.
This poses a branding challenge for archives.
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Current Branding Practice for Web Archives
Page and embedded resources from same Web Archive
Branding for
page and
embedded resources
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Branding for Web Archives in Memento Mode
Will be researched
Page and embedded resources from various Web Archives
Page branding
No branding
No branding
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Overview of Memento Framework
Deployment Progress
Memento and Data
Memento and Discovery
Memento and Branding
Alternative Web Archiving Strategies
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Crawl-based Archives host distinct observations.
Transactional Archives never miss an update.
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Crawl-Based Web Archives
Observations
For example: Heritrix crawler for Internet Archive
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• Collect discreet observations of resources, not their entire evolution.
• Can be rejected (robots.txt, by user-agent, by host IP)
• Can be deceived (cloaking, by geo-location, by user-agent).
• Coverage of particular Web server dependent on crawl-strategy.
Crawl-Based Web Archives
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Server-Side Transactional Web Archives
Change History
For example: TTApache, PageVault, Vignette Web Capture
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• Collect all representations served by to-be-archived server.
• To-be-archived server needs to cooperate. • Incentives e.g. institutional memory, official record of Web presence.
• Archival coverage restricted by to-be-archived server, does not include external servers (e.g. embedded resources).
• To be archived server can submit falsified information.
• Archival collection management: what to keep, what not (e.g. significant changes, deduplication, …).
Server-Side Transactional Web Archives
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Development of Transactional Web Archive Software
Submit: • Java-Grizzly-Jersey submission interface application; • Berkeley DB metadata store; • FS store for body and headers.
Capture: • Apache connection filter module (mod_ta) captures URI, headers, body; • Module POSTs in real-time to transactional archive’s Submit URI.
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Development of Transactional Web Archive Software
Development timeline: • Ongoing development (LANL) and testing (ODU); • Submit/Access finalized; development focus on collection management. • Expected release as open source, 3rd Quarter 2011.
Access: • Transactional archive natively supports Memento; • Immediate availability of archived content; • Export of WARC, e.g. for long-term archiving in other environment.
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Memento http://mementoweb.org/
Herbert Van de Sompel Robert Sanderson Michael L. Nelson
Big Leaps Towards Seamless Navigation of the Web of the Past