Trust and persistence for Internet resources

0.15 MB·English

by  Chiara Cirinna, Maurizio Lunghi, Emanuele Bellini

Trust and persistence for internet
resources
MaurizioLunghi,ChiaraCirinnà
EmanueleBellini
Introduction
Internet radically changed our way of working, communicating,
living,producingandaccessinginformation,interactingwithinsti-
tutionsandbodies,buyingthingsandmanagingresources. Now
everything is available on an open and flexible infrastructure, of-
tenfreelyaccessibletoalltheusers: contentsareusablebymany
servicestailoredtotheuserrequirements. Thewebhasprobably
beenthekillerapplicationfortheinternet. Inthepastfewyears,the
webmovedfromawebofdocumentstowardsawebofdatawhere
informationisnomorepackagedinfixeddocumentsbutisavailable
inade-structuredwayandusableinamoreflexiblewaybyusers.
Therecentdevelopmentsonthewebwitnessedtheemergenceof
thesemanticwebtechnologiesandthelinkedopendata1approach,
associatedwithanincreasinglylargeamountofdataavailablefor
publishingandconnectingstructureddataontheweb. Linkeddata
bestpractices,supportedbyW3C,2 arenowreadytobeendorsed
1http://www.w3.org/wiki/SweoIG/TaskForces/CommunityProjects/
LinkingOpenData.
2W3C-http://www.w3c.it.
JLIS.it.Vol.4,n.1(Gennaio/January2013).
DOI:10.4403/jlis.it-5494
M.Lunghi,Trustandpersistenceforinternetresources
byarelevantnumberofdataproviders,leadingtothecreationofa
globaldataspace-thewebofdata. Unfortunately,theLOD5stars3
aremainlyorientedtowardstheusabilityandstandardizationof
datapublishedonthewebwithoutconsideringthetrustabilityand
persistenceofthedataandtheURIusedtorefertothem. Infact
the objective of the LOD approach seems to be oriented to make
ahugenumberofdataonthewebaccessibleinanon-proprietary
format(e.g. CSVinsteadofExcel)andtolinkthesedatatoother
datasets(e.g. Genomes4orDBpedia5)todisambiguatecontentand
toprovideacontext. However,insomecases,andespeciallyinthe
cultural and educational domains, besides retrieving the needed
dataortheirrelations,itisalsoequallyimportanttogetinformation
abouttheirauthenticity,integrityandprovenance. Systemsforcerti-
ficationusingPIsfordigitalobjects,forauthorsandforinstitutions
can be of great help in order to refine the quality of information
retrievablefrominternetandtolargelyincreaseitsusabilityandthe
developmentofpotentialnewservices. Thisparadigmbasedonthe
identificationandinterconnectionofdataofferssolutionstomany
oftheactuallibraryissues,likeenhancedwebsearching,authority
control,classification,dataportabilityanddisambiguation. Inthe
webofdocumentsidentificationandtrustwereprovidedbyweb
sitesandinstitutionssupportingthem,inthewebofdatatheyare
integratedinthesinglepieceofdata.Theevolutionofthisparadigm
isincreasinglyimportantinavisionforthelongtermcurationof
thedigitalresources.
3http://www.w3.org/DesignIssues/LinkedData.html.
4http://www.geonames.org/ontology/documentation.html.
5http://en.wikipedia.org/wiki/DBpedia.
JLIS.it. Vol.4,n.1(Gennaio/January2013).Art.#5494 p.376
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Requirements for the long term curation of
digital resources
Presentlythenumberofscientificandculturalheritagedigital
resourcesmadeavailableontheinternetthroughoutdigitallibrary
applications is constantly growing and it is now crucial to guar-
anteepersistency,authority,reliabilityandwidedisseminationof
resources while supporting their long term curation. One of the
mainrequirementstotacklethisissueistoadoptcredibleandPI
systems within the life cycle of these resources. A PI should be
assignedonlytoresourcesthatarestable,significantfortherelated
user community and suitable with the scope of the identification
system. Anumberofinitiatives,standards,technologiesareavail-
able,butitmaybedifficultforaninstitutiontounderstandwhich
ofthesearemoreappropriatefortheirdigitalobjects. ThePItech-
nologieshelpmakestablethereferencetoadigitalresource,even
ifitiswell-knownthatpersistencyisn’tonlyatechnicalissue. In
factthesetechnologiesarenotobviouslyreliableperse,notechnol-
ogycanexistindefinitelyorguaranteeserviceswithoutatrustable
organizationandclearlydefinedpolicies. InourvisionPIsystems
aremeantastheavailabletechnologyplusatrustableorganization
and precise policies for digital preservation, implemented by the
managers of the related user community. The concept of persis-
tence moves from the commitment of an institution/registration
authoritytoacommitmentoftheentireusercommunityservedby
PI.APIsystemcanbeconsideredasacontractbetweenthefinal
usersandtheservice-providersresponsiblefortheimplementation
andmaintenanceofthePI-serviceandthefunctionalityofthesys-
tem. Fromthispointofview,thepersistenceofaPIdependsalso
onthecommitmentofthecommunitythatpromotesandusesthe
identificationsystemfortheirownresources. Thishappenswhen
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M.Lunghi,Trustandpersistenceforinternetresources
thestandardadoptediseffectivelyorientedtothecommunityre-
quirements and the authority in charge to manage the system is
recognizedbythecommunityitself. Itiswellknownthatthestruc-
turalinstabilityofsimpleURLs(e.g. domainsnolongeravailable)
and related resources (relocation or updating) is one of the main
issuesthatpreventstheuseofinternetasatrustworthyplatformfor
theresearchandthedisseminationofdigitalcontents. Thecurrent
use of the simple URL approach used as persistent digital object
identifierbringsmanyanddocumentedrisksinalongtermvision
notonlyforretrievalandaccessofresourcesbutalsowithrespectto
thelossofreferencetothedigitaldocumentsorthelackofguarantee
ofauthorityandprovenance. Theserisksaffect:
a)theculturalheritageandresearchdomains,preventingtheim-
plementationofreliablecitabilityservices,researchevaluation,
digitalpreservation,access,etc.,
b)thebusinessdomain,preventingtheuseofpurchaseservices
providedontheseobjects,
c)thepublicdomain(e-gov),slowingdownthedematerialization
processofpublicadministrations.
ItisclearthattheproblemisnotonlytofacetheHTTP404error,
but it is moving towards identification systems able to support
authority, reliability, preservation, certification, exploitation and
widedisseminationoftheseresources. Atrustworthysolutionisto
associateatrustedPIwiththedigitalresources.
The challenge of trust
Trust,broadlyspeaking,concernstheassessmentandmanagement
oftherisksperceivedbyeachactorenteringintoarelationship. In
JLIS.it. Vol.4,n.1(Gennaio/January2013).Art.#5494 p.378
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otherwords,”trustentailsrisk”.AccordingtotheISOdefinition,the
riskcanbedefinedasthecombinationoftheprobabilityofanevent
anditsconsequences(ISO/IECGuide73). Thereareanumberof
eventswithbadconsequencesthatcouldoccurduringthelifetime
ofthePIservice,withdifferentdegreesofprobabilitybutallwith
highcostsincaseoffailure. Examplesoftheserisksare:
a)failingtodeterminetheinitialandrecurringcostsandthepricing
ofservice(risksassociatedtothefinancialsustainability),
b)adoptingtechnologiesnolongeravailable(riskassociatedtothe
standardsadoption),
c)theobjectidentifiedisnolongeravailableonthenetwork(riskas-
sociatedtotheagreementbetweencontentandserviceproviders),
d) to lose the support of the community (risk associated to the
communitymandate),etc.
Thesefactorscandeterminatethedecrease(lowering)oftrustwor-
thinessinthePIservicebythecontentproviderandaffectthedis-
seminationandexploitationofdigitalresources. Thevariousdigital
repositories store intangible objects and entities and make them
availabletousersthroughtelematicsnetworks: weaccessourbank
account as well the hospital or the municipality for official docu-
ments,wedownloadtonsoffilesandchatwithavataractors. But
whocertifiestheidentityofactorsandguaranteesourprivacy?How
can we rely on the authenticity of the documents we download?
Andalsohowcanwetrusttheinstituteissuingan‘official’docu-
ment? Whatistheriskifwecannotdemonstratethatadocumentis
notvalidforourexpectedpurposes? Whicharetherisks? Agood
amount of trustworthiness is necessary to live in this virtual and
artificialworld. APIservicemustaddressatleastthefollowingcore
requirements:
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M.Lunghi,Trustandpersistenceforinternetresources
1. globaluniqueness: thePIisclearlypartofanamedomainand
itisuniqueandassociatetoauniqueresource.
2. persistence: itreferstothepermanentlifetimethesignificant
properties of an identifier, for example, it is not possible to
reassignthePItootherresourcesortodeleteit.
3. resolvability: itreferstothepossibilityofretrievinginforma-
tionregardingaresourceortoaccessitdirectlyontheinternet.
Currently, there are different technologies and standards for the
implementationofPIsystems,butthereisn’tageneralagreement
ontheiradoption,oftenbecausesomeofthesesystemswerebornas
technicalsolutions,withoutthesupportofthecommunityofusers
whoneedspecificlevelsofPIservices. SystemslikethePURLor
CoolURIs(Berners-Lee)haveconsiderableadvantagesinsupporting
thewebofdataimplementationthankstothetheirimmediatede-
referenceabilitythroughtheprotocolHTTP,butontheotherhand,
thereareseverallimitationsduetothefactthattheirpersistenceis
notguaranteedinprinciplebyanindependentandtrustablethird
party. ItiswellknownthattheCoolURIapproachtopersistence
is based on the URL design. This approach, even if it is consid-
eredabestpracticefortheimplementationofthesemanticwebin
generalandlinkeddatainparticular,ismainlybasedontechnical
solutions. ThebasicassumptionisthatacorrectdesignoftheURI
should reduce the need to change them in order to ensure their
stabilityovertime. Anexampleofthisbestpracticeistoavoidthe
explicitextensionofwebpagesas.phpor.aspsothatchangesin
technologyimplementationdonotaffecttheURIform(e.g. from
PHPtoASP).Inthisperspective,thepersistenceisbaseduniquely
onthecommitmentofindividualinstitutionsestablishingatrusted
relationshipdirectlywiththefinalusers,withoutthemediationof
athirdparty. Unfortunately,itiswellknownthatthecommitment
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ofasingleinstitutionisnolongersufficienttoensureneitherlong
termpersistenceofURLsnorthetrustworthinessoftheresources
in terms of provenance, authenticity, integrity, conservation, and
soon. Inpracticeresourcesaremovingonthenetwork,theycan
be changed or deleted due to a multitude of factors that cannot
alwaysbepredeterminedorregulatedbythecontentmanagement
policiesofinstitutionsorgovernedbybestpracticetechniques. A
typicalcaseoccurswhenaninstitutionrunsoutbecauseithasbeen
absorbedbyanotherinstitution, oritissuppressed, orsimplyits
officialnamehaschanged. Inthesecases,thedigitalobjectscanbe
renamedtobeadaptedtotheworkflowofthenewinstitution,or
transferredtootherinstitutions, oratworstdeletedbecausethey
arenolongerrelevanttoinstitutionalgoals. Itisclearthatallthese
actions can cause the breaking of the old URLs independently of
howtheywerebuilt. Thismaynotbeaproblemiftheinstitution
doesnothandlescientific,culturaloradministrativeresourcesbut
it becomes a critical issue if these changes affect institutions like
scientificdatastore,libraries,archives,governmentaldataset,andso
forth. Inthesecases,forexample,bibliographiesbasedonsimple
URLorevencoolURIreferringtoresourcesthatwerepresentin
the archives of these institutions, can no longer be used to check
the scientific work or to calculate bibliometric indexes. Another
criticalissueisrelatedtotheconnectionofdatasetswhichhavebeen
updated several times. In such cases, it may be difficult or even
impossibletoverifythevalidityofthescientificoutcomepresented
inarelatedpaper. Whatismostcritical,however,istheimpossibil-
itytoimplementsystemstochecktheauthenticity,provenanceand
integrityoftheseresourcesbecauseoftheabsenceofathirdparty
abletoguaranteetheassociationname-resource. Inthisscenario,
mostbenefitsofawideaccesstolinkeddatasetaredissolvedbythe
lackoftheirreliability.
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M.Lunghi,Trustandpersistenceforinternetresources
NBN:IT service as a support of trust LOD
TotacklethechallengeoftrustinLOD,apossiblesolutioncould
betoadoptaURNbasedPIsolutions.6 Presently,toimplementa
PIsystem,themainapproachistoseparatetheidentificationfrom
thelocalisationoftheresources. Asshownabove,TimBernerLee
advisesthatadoptingclearandstablepoliciesandimplementation
guidelines is sufficient to manage the persistent identification of
resourcesontheinternet. Evenifthissuggestionisreasonableand
appropriateinsomedomains,itisevidentthatwecannotdelegate
thisresponsibilitytoeachinstitution,inparticularinthescientific
andculturalheritagedomainfortwomainreasons:
1. manyinstitutionsfailtodecidetheapproachandthestrategy
tobeadoptedintermsofcontentselection,formats,naming,
etc.;
2. manyinstitutionsfailtodecidetheapproachandthestrategy
tobeadoptedintermsofcontentselection,formats,naming,
etc.;
Inanycase,UniforumResourceIdentifiers(URIs)arewidelyused
inthesemanticwebcontexttoidentifyanytypeofresourcesorany
real,digital,abstract,virtualobject,tryingtoharmoniseinaseman-
tic vision all the user communities applications. For instance, to
addressthisissue,theinfo-URIscheme7wasdevelopedbylibraries
andpublishingcommunitiesfor”URIsofinformationassetsthat
haveidentifiersinpublicnamespacesbuthavenorepresentation
withintheURIallocation”. Itisclearthat,inordertorefertoacerti-
fieddigitalobjectinatrustableway,theuseofURNoridentifiers
6APARSEN DE22.1 Persistent Identifiers Interoperability Framework - http:
//www.alliancepermanentaccess.org/wp-content/plugins/download-monitor/
download.php?id=D22.1+Persistent+Identifiers+Interoperability+Framework.
7RFC4452:http://info-uri.info.
JLIS.it. Vol.4,n.1(Gennaio/January2013).Art.#5494 p.382
JLIS.it.Vol.4,n.1(Gennaio/January2013)
thatimplementstheRFC1737(FunctionalrequirementsforUniform
ResourceNames)istodayabestpractice. ThepurposeofaURN
istoprovideagloballyunique,persistent,location-independentre-
sourceidentifierwhichcanbeusedfortheidentificationandaccess
tothecharacteristicsofaresourceorfortheaccesstotheresource
itself. TheURNspecificationispartoftheIETFfamilyofspecifi-
cationsencompassedbytheURIframework. Thisframeworkalso
includesURLs,whichspecifybothaprotocolandalocationinorder
to give access to resources on the web. IANA is the registration
authorityforURNnamespaces. URNsaredesignedtoenablehet-
erogeneousnamespacesmappingontoaURN-space,andtherefore
enable the reuse of well-known identifiers. Unlike URLs, URNs
arenotdirectlyactionable(browsersgenerallydonotknowwhat
todowithaURN)becausetheyhavenoassociatedglobalinfras-
tructurethatenablesresolution(suchastheDNSsupportingURL).
Althoughseveralimplementationshavebeenmade,eachproposing
itsownmeansforresolutionthroughtheuseofplug-insorproxy
servers,aninfrastructurethatenableslargescaleresolutionhasnot
beenimplemented. Butsingleimplementationsofnamespace,like
theURN-NBNortheDOI,offeraresolution-serviceavailableon
internet. TheNBNnamespace,asanamespaceidentifier(NID),has
beenregisteredandadoptedbytheNordicMetadataProjectsbutis
beingseparatelyimplementedbyindividualsystemswithnorefer-
enceimplementationwhichenablethecoordinationofinformation
sources. Infact,severalnationallibrarieshavedevelopedtheirown
NBNsystemswithinnationalprojects;severalimplementationsare
currentlyinuse,eachwithdifferentdescriptivemetadataorgranu-
laritylevels. Accordingtothis,itisclearthatthePIs,cannotsupport
theLODtrustworthinesssuccessfully. TheNBN-Italyservicesup-
portsatleastthreelevelsofpersistence:(Bellinietal.,“TheNational
BibliographyNumberItalia(NBN:IT)Project. Apersistentidentifier
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supportingnationallegaldepositfordigitalresources”)
1. Persistence of the identifier NBN. If the resource is no longer
availableonline,theURNidentifierwillbemaintained(e.g. as
proofthatatsomepointthatresourcehasexisted);
2. PersistenceoftheassociationURNsandURLs. Itisacommitment
thatensuresthatinthelongtermURNisresolvable(which
leadsatleasttoanaddressofURLtype). Theaccessibilityto
theresourceisnotguaranteedbutisassuredtheaccesstothe
theso-called”Tombstone”iftheresourceisnolongeravailable
onthenetwork(e.g. ”Thisebookisnolongeronthemarket”);
3. PersistenceoftheresourcereferencedbyNBN.Ensuringlong-term
existence and accessibility the resource referenced by URN.
ThisisthelevelofpersistenceofNBNmadepossiblethanks
tothestorage(statutoryorvoluntary)atthenationallibraries
andauthoritativedescriptionofthenationalbibliography.
Thankstotheselevelsofservice,NBN-Italynamesrepresentaclear
addedvalueifusedintheLODarchitecturestosupportthetrustwor-
thinessoftheassertions(RDFtriple).Thisproposalgoestowardsthe
integrationoftheLODandPIsystems,byexploitingtheon-going
initiativesandprojectsasoutlinedinthenextparagraph.
Next steps: Den Haag Manifesto 2.0 and
Florence Agenda
Theforthcomingevent”CulturalHeritageOnLine2012”thatwill
beheldinFlorenceinDecember2012aimstoimproveandmakeef-
fectivethe”DenHagueManifesto”throughtheunionofseveralon-
goingrelatedinitiatives,projectsandstakeholderslike: APARSEN
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