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PERSISTENT IDENTIFICATION SYSTEMS
Part 3 : The Achievement of Persistence of Access to Resources

A system of persistent identifiers is only one tool that can assist in the achievement of persistent access to resources. Good information management practices are a prerequisite for the effective use of persistent identifiers.

It is important to avoid instilling in resource owners and publishers the expectation that if they assign a persistent identifier, somehow permanence and persistence is assured. Persistence will always be a managed process, both at the global level in terms of the resolver services used to route requests based on identifiers to the custodians of resources and metadata, and at the local level to ensure that the identifier is associated with the resource and the request can be met. There is no system that can avoid a serious and sustained commitment to persistence by those organisations that wish to preserve public access to electronic documents.

Name persistence is not a technological problem. Some schemes will provide more reliable tools to achieve such persistence, but whatever system is used, persistence of citation will be achieved through the commitment of institutions responsible for assigning the names and maintaining the resolution services, not by the inherent qualities of the names themselves.

It is possible, and indeed desirable, in the absence of URN or name style identifiers to manage URLs better. They can be managed with a resolver database, with redirects, with PURLs, and this can be done now. The organisation and discipline required to do this is a prerequisite for implementing any other system of identifiers at a later time.

3.1 What categories of material need to be managed for persistence?

There are many categories of material that need to be managed for persistence. Some of these are obvious, such as material which is archived for the long term, others are less obvious, such as a web page which describes the opening hours of a library which may have been bookmarked by many users of that library.

The best rule of thumb is that any item which has been made publicly available online and which is likely to have been cited or referenced in other digital objects or online resources should be organised in such a way that citations to it persist. This should be done regardless of whether the item in question is subject to a formal archiving policy. Persistent and unambiguous identification for online digital resources currently made available on the web is essential, and for archival materials, this identification should also be location and protocol independent.

This is crucial for a number of applications:

Citation of online documents.

An increasing number of scholarly papers, research reports and significant documents and reports, including government documents, are available only online, mainly on the web. Many more are made available in both hardcopy and online form. These digital documents often cite other online documents in the form of links to those documents. This has two implications, firstly it is necessary to unambiguously identify the item referred to, secondly there is an expectation that the link will continue to be actionable while the document is available online.

There are many examples of documents cited in lists, references in papers and resources indexed in search engine databases which can no longer be accessed at the address cited. The researcher coming across such a dead end is faced with a number of questions Does the resource still exist?, If it does, where is it?, and finally, If I find something which looks like it, is it the same?

Archiving of digital materials

Persistent identification is also an essential tool in the archiving of digital materials. There is a strong association between the issue of identification and the preservation issue in the sense that persistence of identification is essential for reliable long-term access and is one of the main reasons libraries and archives have such a strong interest in persistent identification schemes. The value of preserving material is reduced if it cannot be identified reliably, found, and accessed when cited or referenced. It is therefore important that we have functioning identification scheme(s) that leave no doubt as to the commitment to persistence implied by the use of such an identifier.

Multiple copies

There are occasions when multiple copies of a resource exist at different locations. These may be identical and they need to be identified as such. This is not possible with an identifier based on location. Examples are mirror sites and archival copies and the original work, or a resource which may be made available via a web site and an ftp server.

Rights management/access management

Rights management and access management need unambiguous identification of a resource for machine processing, hence the publishing industry and those holding intellectual property rights in online resources also have an interest in persistent identification. Because automated, commercial transactions may be involved, industrial strength persistent identification is critical. This is the reason the publishing industry have developed the their own identifier system, the DOI (Digital Object Identifier)

Catalogues, indexes and resource discovery services

Persistent identifiers are also essential for general linking in catalogues, indexes and gateways. In addition to being an irritation for users trying to access material, constant change and movements of material which change the identifiers of that material can impose an unacceptable maintenance burden on the maintainers of lists, indexes, gateways or catalogues of WWW materials. Libraries and archives therefore must have a keen interest in the development and implementation of permanent identifier systems that are independent of location. There is a general expectation that links in online documents and resources will work.

Bookmarks

Although all of the categories mentioned above may also be bookmarked in personal web browsers, there is a category of material which is frequently bookmarked but which may not be of long-term significance, e.g. the opening hours page of a library website, the What’s new or events calendar of an organisation. While these may not have long-term value and will not usually be accorded archival treatment, any organisation with a service orientation would ensure that they are managed for persistence so that clients who consult them on a regular basis are not inconvenienced.

There is no doubt that an effective system of persistent identifiers will assist in the task of ensuring the long-term reliability of links. However the absence of a persistent identifier system does not mean that nothing can be done. Good data management and an understanding of the issues is a prerequisite for the introduction of a persistent identifier system. There are a number of positive steps that can be undertaken to prepare the ground whilst a system is being developed, including:

  • Promotion of the concept of persistence of naming and the need to manage for persistence.
  • Developing and promoting guidelines for managing for persistence
  • Leading by example by developing a data management plan for the NLA website.
  • Working with others to promote adoption and trial systems.

We have little control over what others do but there are many ways we can assist them in the development of best practice in the way they treat their information/resources.

3.2 Promote the concept of persistence

3.2.1. Encourage awareness

There is not yet a general awareness of the value of managing for persistence and the important role that can be played by the individual institution with a relatively small commitment of resources.

The NLA can encourage an awareness of the importance of managing for persistence as a precursor to archiving. Archiving can seem daunting because of the newness of the field and the complexity of the issues, many of which have yet to be fully appreciated and addressed. This can be discouraging to those who may feel that they do not have the resources or expertise to undertake the task. It is important to emphasise that there are many things that can be done now to achieve persistence of citation and to ensure that materials are identified for retention online. This will at least ensure that valuable information is not lost while the digital preservation field matures.

3.2.2 Develop guidelines for best practice management for persistence

Developing a set of guidelines for best practice management for persistence can assist in a variety of ways:

  • Many people in large institutions do not have control over the organisation of the institutional website, although they may be the owners of some of the content and be responsible for other parts of it. Others may have outsourced the development and management of the site. The guidelines envisaged would assist those responsible for the content of the site to state their requirements for persistence and negotiate strategies for achieving it.
  • Many of those responsible for their own sites do not have the time or resources to research and document the actions they might take. A set of guidelines that sets out the options may help this group of users to take the first steps.

These guidelines should cover consideration of the issues mentioned above, including data management policy, as well as hints on organising the site, file structures, etc. This is work that would have to be undertaken prior to the implementation of a persistent identifier system. It is likely that those already accustomed to managing for persistence will take the next step and use persistent identifiers. [This has already been implemented in the form of Managing web resources for persistent access brochure]

Recommendation 6

That the Library continues to promote awareness of the value of good information management practices, especially managing for persistence.

3.2.3 Lead by example

One of the tools for managing for persistence is the development of a data management strategy for online resources. In order to manage for persistence in the long-term, we need to be able to identify clearly the materials we wish to preserve access to, and which are also therefore candidates for persistent identifiers.

The library can lead by example in this process by developing an integrated data retention and access policy for our own resources, including not only Pandora and the digital surrogates, but also the website and TRIM. It is likely that a policy for the latter categories will be of greatest relevance to the wider community. The policy for digital surrogates and the material in Pandora is fairly obvious and clear cut, but there are grey areas for materials which exist in multiple instantiations, e.g. items which exist in the records management system (TRIM), hard copy and online on the website. This is a situation which is common to many sites such as government and academic institutions which have significant information that is frequently cited.

It has been argued that material on the NLA website does not need to be regarded as permanent because the site is just a delivery mechanism and the preservation aspect is taken care of by the copying of the website mandated by Australian Archives and the routine electronic records management process, also mandated by Australian Archives. However, neither of these processes preserves persistent access to material that has been made publicly available online. Much of this material, especially position papers, staff papers and policy documents will be cited in other online documents, gateways and collections of resources online. These citations are made to the web version and if that version is subsequently removed from the site, links to it are broken. For this reason, such resources must be managed for persistence and are candidates for persistent identifiers.

Material cited on the website will fall into two categories:

  • static resources
  • dynamic resources (note that databases, e.g. RAAM, ALG, are not considered here as they are not candidates for persistent identifiers, except at the service entry points and help pages.)

Static resources include items which have a definitive version and will not be altered, e.g. a policy document, an annual report, a conference paper, all of which reflect the point of time at which they were created. Most of this category will be managed for long-term persistence of access.

Dynamic resources are materials that undergo change, either incremental change by addition of content or change by modification, deletion and insertion of content. They can be either ephemeral or archival.

The ephemeral category includes What’s new, What’s on, opening hours, contact information, lists of current publications, charging policies, etc. These are not likely to be cited in other objects, but are frequently bookmarked for regular use and users want the latest version. Old versions are of no particular interest and the normal records management and archival policies can take care of the information needs of the future researcher and policy maker. This category needs persistence of citation, but only for the current version.

The archival category includes material that will be preserved and guaranteed persistent access. The decision about what level of persistence of access to provide will be a matter of judgement and will depend on the nature of the material. E.g. for an electronic journal such as Gateways that operates in an incremental fashion, it may be necessary to provide consistent access to both the home page and to individual issues and articles for citation purposes; whilst for a publication which may be modified by change, addition and deletion, decisions will be needed on whether to archive and provide public access to successive versions so that little information is lost and the evolving nature of the publication is documented, or whether to rely on the routine archival copying to provide future access.

Other types of material can be left to the normal business process and require no management for persistence, e.g. Registration page for a conference, entry point for a service no longer offered (although while it is alive, it should be managed for persistence of access), temporary alerts such as the recent V8 car race information.

A detailed analysis and typology of the information on the site and policies on the identification and organisation of the material will enable those responsible for managing it to decide at the point of creation of a document what level of persistence is required and it can be located, flagged and named accordingly. To all intents and purposes, some of these access copies of material will be treated as de facto archival material even though the official preservation copy may reside in the records management system.

Management for persistence of access is an important service to the community served by a website.

Recommendation 7

That the Library develops a data management and archival strategy for its own online resources, addressing specifically the relationship between the routine management and archiving of electronic records as part of the business process and the requirement to ensure persistent access to certain categories of resources which have been made publicly available on the website.

3.2 4 Work with others to promote management for persistence and development of PI systems.

There are a number of organisations that have a common interest in the achievement of persistence of citation for significant information sources. The most obvious of these are archives and libraries, particularly, but not limited to, state and academic libraries.

National Archives of Australia has responsibility for the preservation of government records. It discharges this responsibility by requiring agencies to preserve electronic records and by periodically copying their websites. There is, however, no requirement that documents that have been made publicly available online remain accessible so that links to them remain actionable. This is a serious deficiency, given the significance of many government reports and papers and the value of much government information to researchers and policy makers.

The old AGPS deposit scheme operated by the Commonwealth government deposited copies of Commonwealth government publications in National and State libraries to ensure widespread access to government information. It could be argued that in the online environment, this aim can be achieved by requiring not only the preservation of documents which have appeared on websites, but by mandating that websites be managed to ensure that important reports and documents remain accessible online and be managed for persistence so that citations to them are remain actionable. The NLA and National Archives of Australia should work together on this. The National Archives are responsible for the preservation of electronic resources that form the record of the business processes of Commonwealth government agencies and the National Library for the preservation of the published record. The convergence of the two functions in the electronic environment has blurred the distinction between them. There is a need to address and agree upon processes and strategies for achieving persistence of access to government electronic resources published on websites.

The state libraries and academic libraries also have a vested interest in persistent access to online digital resources and may be willing to work with the Library. CASL and CAUL may be vehicles for publicising and addressing the issues within their respective communities of interest.

Recommendation 8

That the Library work with other interested bodies, in particular custodial institutions and publishers, to promote the use of persistent identifiers for online resources.

4. Summary of recommendations contained in the report

Recommendation 1

That the Library postpone a decision on implementation of an external resolution mechanism for persistent identifiers and that, for the time being, persistence of our own resources be achieved through a combination of managed URLs and a resolver system based on directing query strings to our application delivery mechanisms for digital materials. (See Appendix 2)

That this decision be re-examined in the first quarter of 2002 in the light of positive developments that may have taken place in the intervening period. (Section 2.3)

Recommendation 2

That the Library formally adopt the naming guidelines outlined scheme in Appendix 1

That the Library develop a naming scheme for archival resources in consultation with the state libraries and archives. The scheme should be designed for distributed assignment based on a pattern of naming authority and local string to guarantee uniqueness and that the syntax of the identifier separate the naming authority component from the local string in a way that will allow machine identification of the two components. This will facilitate migration to a global system at a later date if one of them is implemented. In the short term, it will be accessed using standard URLs (Section 2.4)

Recommendation 3

That the Library actively monitor developments relating to existing identifier schemes, (Section 2.5). In particular:

  • Possible establishment of a W3C working group on URI issues. The Library should join W3C working group if one is established and support rationalisation of URI and URN procedures to assist acceptance of standards and development of URN enabled browsers.
  • The progress of DOI deployment and the establishment of Registration Authorities. It would also be worthwhile canvassing the views of publishers, libraries and archives on the issue of use of DOI.
  • The progress and possible deployment of the latest IETF proposals on the Dynamic Delegation Discovery System (DDDS) issued as an Internet draft in February 2001. The DDDS approach is to use the DNS to locate resolvers that can provide information on individual resources, potentially including the resource itself. If this becomes a standard, it may be possible for an interested group of custodial institutions to support resolution of their identifiers using the domain name system as a resolver discovery service
  • Monitor ARK developments. The ARK has the potential to be a significant development for libraries, archives and other custodial institutions.

Recommendation 4

That the Library revisit discussions in CDNL with a view to i) affirming support for a number of identifier systems used by national libraries and. ii) exploring the possibilities of developing and trialling shared resolution systems for identifiers used by national libraries and other custodial institutions. (Section 2.5.2)

Recommendation 5

That the Library explores the outstanding issues of metadata, publishers identifiers and their relationship with archival URLs (Section 2.6)

Recommendation 6

That the Library continue to promote awareness of the value of good information management practices, especially managing for persistence. (Section 3.2)

Recommendation 7

That the Library develops a data management and archival strategy for its own online resources, addressing specifically the relationship between the routine management and archiving of electronic records as part of the business process and the requirement to ensure persistent access to certain categories of resources which have been made publicly available on the website. (Section 3.2.3)

Recommendation 8

That the Library work with other interested bodies, in particular custodial institutions and publishers, to promote the use of persistent identifiers for online resources. (Section 3.2.4)

Return to Table of Contents | Proceed to Appendix 1
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