The theory and practice of Website Archivability

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  • Abstract: Web archiving is crucial to ensure that cultural, scientificand social heritage on the web remains accessible and usableover time. A key aspect of the web archiving process is opti-mal data extraction from target websites. This procedure isdifficult for such reasons as, website complexity, plethora ofunderlying technologies and ultimately the open-ended na-ture of the web. The purpose of this work is to establishthe notion of Website Archivability (WA) and to introducethe Credible Live Evaluation of Archive Readiness (CLEAR)method to measureWA for any website. Website Archivabil-ity captures the core aspects of a website crucial in diagnos-ing whether it has the potentiality to be archived with com-pleteness and accuracy. An appreciation of the archivabilityof a web site should provide archivists with a valuable toolwhen assessing the possibilities of archiving material and in-fluence web design professionals to consider the implicationsof their design decisions on the likelihood could be archived.A prototype application, archiveready.com, has been estab-lished to demonstrate the viabiity of the proposed methodfor assessing Website Archivability.
  • Web content acquisition is a critical step in the process of web archiving;If the initial Submission Information Package lacks completeness and accuracy for any reason (e.g. missing or invalid web content), the rest of the preservation processes are rendered useless;There is no guarantee that web bots dedicated to retrieving website content can access and retrieve it successfully;Web bots face increasing difficulties in harvesting websites.Efforts to deploy crowdsourced techniques to manage QA provide an indication of how significant the bottleneck is.Dirty data -> useless systemAs websites become more sophisticated and complex, the difficulties that web bots face in harvesting them increase.For instance, some web bots have limited abilities to process GIS les, dynamic web content, or streaming media [16]. Toovercome these obstacles, standards have been developed to make websites more amenable to harvesting by web bots.Two examples are the Sitemaps.xml and Robots.txt protocols. Such protocols are not used universally.
  • Website archivability must not be confused with website dependability, the former refers to the ability to archive a website while the latter is a system property that integrates such attributes as reliability, availability, safety, security, survivability and maintainability[1].Support web archivists in decision making, in order to improve the quality of web archives.Expand and optimize the knowledge and practices of web archivists.Standardize the web aggregation practices of web archives, especially QA.Foster good practices in web development, make sites more amenable to harvesting, ingesting, and preserving.Raise awareness among web professionals regarding preservation.
  • The concept of CLEAR emerged from our current research in web preservation in the context of the BlogForever project which involves weblog harvesting and archiving. Our work revealed the need for a method to assess website archive readiness in order to support web archiving workflows.
  • Already contacted by the following institutionsThe Internet Archive,University of Manchester,Columbia University Libraries,Society of California Archivists General Assembly,Old Dominion University, Virginia, USA,Digital Archivists in Netherlands.
  • For instance Metadata breadth and depth might be critical for a particular web archiving research task andtherefore in establishing the archivability score for a particular site the user may which to instantiate this thinking incalculating the overall score. A next step will be to introduce a mechanism to allow the user to weight each Archivability Facet to reflect specific objectives.One way to address these concerns might be to apply an ap-proach similar to normalized discounted cummulative gain(NDCG) in information retrieval49: for example, a user canrank the questions/errors to prioritise them for each facet.The basic archivability score can be adjusted to penalise theoutcome when the website does not meet the higher rankedcriteria. Further experimentation with the tool will lead toa richer understanding of new directions in automation inweb archiving.
  • The theory and practice of Website Archivability

    1. 1. The Theory and Practice of Website Archivability Vangelis Banos1, Yunhyong Kim2, Seamus Ross2, Yannis Manolopoulos1 1Department of Informatics, Aristotle University, Thessaloniki , Greece 2University of Glasgow, United Kingdom FROM CLEAR TO ARCHIVEREADY.COM
    2. 2. 2 Table of Contents 1. Problem definition, 2. CLEAR: A Credible Live Method to Evaluate Website Archivability, 3. Demo: http://archiveready.com/, 4. Future Work.
    3. 3. Problem definition • Web content acquisition is a critical step in the process of web archiving, • Web bots face increasing difficulties in harvesting websites, • After web harvesting, archive administrators review manually the content and endorse or reject the harvested material, • Key Problem: Web harvesting is automated while Quality Assurance (QA) is manual. 3
    4. 4. Website Archivability ? What is Website Archivability captures the core aspects of a website crucial in diagnosing whether it has the potentiality to be archived with completeness and accuracy. Attention! it must not be confused with website dependability, reliability, availability, safety, security, survivability, maintainability.
    5. 5. CLEAR: A Credible Live Method to Evaluate Website Archivability • An approach to producing a credible on-the-fly measurement of Website Archivability, by: • Using standard HTTP to get website elements, • Evaluating information such as file types, content encoding and transfer errors, • Combining this information with an evaluation of the website's compliance with recognised practices in digital curation, • Using adopted standards, validating formats, assigning metadata • Calculating Website Archivability Score (0 – 100%) 5
    6. 6. 6 Accessibility Cohesion Standards Compliance Performance Metadata CLEAR: A Credible Live Method to Evaluate Website Archivability
    7. 7. 7 Website attributes evaluated using CLEAR
    8. 8. 8 C L E A R • The method can be summarised as follows: 1. Perform specific Evaluations on Website Attributes, 2. In order to calculate each Archivability Facet’s score, • Scores range from (0 – 100%), • Not all evaluations are equal, if an important evaluation fails, score = 0, if a minor evaluation fails, score = 50% 3. Producing the final Website Archivability as the sum all Facets’ scores.
    9. 9. Accessibility 9 Are web archiving crawlers able to discover all content using standard protocols and best practices?
    10. 10. Accessibility evaluation 10 Facet Evaluation Rating Total Accessibility No RSS feed 50% 50% No robots.txt 50% No sitemap.xml 0% 6 links, all valid 100% http://ipres2013.ist.utl.pt/ Website Archivability evaluation on 23rd April 2013
    11. 11. Cohesion 11 • Dependencies are a great issue in digital curation. • If a website is dispersed across different web locations (images, javascripts, CSS, CDNs, etc), the acquisition and ingest is likely to risk suffering if one or more web locations fail on change. • Web bots may have issues accessing a lot of different web locations due to configuration issues.
    12. 12. Cohesion evaluation 12 Facet Evaluation Rating Total Cohesion 1 external and no internal scripts 0% 70% 4 local and 1 external images 80% No proprietary (Quicktime & Flash) files 100% 1 local CSS file 100% http://ipres2013.ist.utl.pt/ Website Archivability evaluation on 23rd April 2013
    13. 13. Metadata 13 • Metadata are necessary for digital curation and archiving. • Lack of metadata impairs the ability to manage, organise, retrieve and interact with content. • Web content metadata may be: • Syntactic: (e.g. content encoding, character set) • Semantic: (e.g. description, keywords, dates) • Pragmatic: (e.g. FOAF, RDF, Dublin Core)
    14. 14. Metadata evaluation 14 Facet Evaluation Rating Total Metadata Meta description found 100% 87% HTTP Content type 100% HTTP Page expiration not found 50% HTTP Last-modified found 100% http://ipres2013.ist.utl.pt/ Website Archivability evaluation on 23rd April 2013
    15. 15. Performance 15 • Calculate the average network response time for all website content. • The throughput of web spider data acquisition affects the number and complexity of the web sources it can process. • Performance evaluation: Facet Evaluation Rating Total Performance Average network response time is 0.546ms 100% 100% http://ipres2013.ist.utl.pt/ Website Archivability evaluation on 23rd April 2013
    16. 16. Standards Compliance 16 • Digital curation best practices recommend that web resources must be represented in known and transparent standards, in order to be preserved.
    17. 17. Standards Compliance evaluation 17 Facet Evaluation Rating Total Standards Compliance 1 Invalid CSS file 0% 87% Invalid HTML file 0% Meta description found 100% No HTTP Content encoding 50% HTTP Content Type found 100% HTTP Page expiration found 100% HTTP Last-modified found 100% No Quicktime or Flash objects 100% 5 images found and validated with JHOVE 100% http://ipres2013.ist.utl.pt/ Website Archivability evaluation on 23rd April 2013
    18. 18. iPRES 2013 Website Archivability Evaluation 18 Facet Rating Website Archivability Accessibility 50% 77% Cohesion 70% Standards Compliance 77% Metadata 87% Performance 100%
    19. 19. ArchiveReady.com Demonstration - Web application implementing CLEAR, - Web interface & also Web API in JSON, - Running on Linux, Python, Nginx, Redis, Mysql. 19
    20. 20. Impact 20 1. Web professionals - evaluate the archivability of their websites in an easy but thorough way, - become aware of web preservation concepts, - embrace preservation-friendly practices. 2. Web archive operators - make informed decisions on archiving websites, - perform large scale website evaluations with ease, - automate web archiving Quality Assurance, - minimise wasted resources on problematic websites.
    21. 21. 21 Future Work 1. Not optimal to treat all Archivability Facets as equal. 2. Evaluating a single website page, based on the assumption that web pages from the same website share the same components and standards. Sampling would be necessary. 3. Certain classes and specific types of errors create lesser or greater obstacles to website acquisition and ingest than others. Differential valuing of error classes and types is necessary. 4. Cross validation with web archive data is under way
    22. 22. THANK YOU Vangelis Banos Web: http://vbanos.gr/ Email: vbanos@gmail.com ANY QUESTIONS? 22 The research leading to these results has received funding from the European Commission Framework Programme 7 (FP7), BlogForever project, grant agreement No.269963.

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