by Gérald Jean Francis Banon
November 2023
Updated in june 2025
The need to preserve digital information in the long term is a primary concern of many initiatives, one of which is the development of the Reference Model for an Open Archival Information System (OAIS) by the Consultative Committee on Spatial Data Systems (CCSDS) and the International Organization for Standardization (ISO) [1].
One of the open preservation problem is how to maintain the integrity of hyperlinks in the Long-Term, which may extend indefinitely.
The purpose of this note is to illustrate the existence of a digital service for a Federation of Archives (Digital Repositories - Data Providers) that allows persistent hyperlinks to work with distributed local resolvers instead of a global resolver.
This HTML page contains two examples of Fully Persistent Hyperlinks. Each hyperlink points to an identifier within some specified namespace. The first uses the IBI namespace (identified by upn:4CR88AP) and the second the DOI namespace (identified by urn:doi).
This page is the Data Object (Digital Object) of an Archival Information Package (AIP) hosted in an Archive that is a member of a Federation of Archives, where the Federation is of the type Distributed Access Aid, and where all the members are global nodes in the Federation [1].
The Federation currently has the following members (the first is the one that hosts this HTML page): Additionally, each federated global node identifies its AIPs using IBI identifiers [2] and it acts both as a data provider and an IBI local resolver.
A Namespace is a set of names.
An Identifier (of an object) is a name within a specific namespace that is assigned exclusively and forever to that object.
A Hyperlink (from a Source Object - SO to a Destination Object - DO) is a digital procedure whose call is inserted into the SO and, when activated, brings the DO on the user's screen, and whose argument specifies the location of the DO on the Web.
A Persistent Hyperlink (from a Source Object - SO to a Destination Object - DO) is a digital procedure whose call is inserted into the SO and, when activated, brings the DO on the user's screen, and whose argument specifies a URL scheme, a resolver domain name and the DO Identifier that is used by the resolver to find the current DO location on the Web.
An Almost Fully Persistent Hyperlink (from a Source Object - SO to a Destination Object - DO) is a relative Persistent Hyperlink (from the SO to the DO). In other words, the digital procedure argument specifies neither the URL scheme nor the resolver domain name, but it does specify the namespace identifier. In the background, the DO Identifier may need be resolved by a global resolver.
A Fully Persistent Hyperlink (from a Source Object - SO to a Destination Object - DO, both belonging to a Federation of Archives) is a relative Persistent Hyperlink (from the SO to the DO) whose DO Identifier is resolved by the SO data provider itself acting as a local resolver of the Federation, that is, the resolution is done without the help of a global resolver. In other words, the resolution process is not centralized, but distributed.
Examples of two Almost Fully Persistent Hyperlinks are given in [3]. In the next section, examples of two Fully Persistent Hyperlinks are now given.
The two hyperlinks below are relative Persistent Hyperlinks†. This can be verified by looking at the value of the respective href attribute in the source code of this HTML page.
They are Fully Persistent because the SO (i.e., the AIP containing this page) and the two DOs cited in this page are parts of the same Federation of Archives (see its members above, at the end of the Introduction), and the data provider of the SO acts as a local resolver for the Federation (i.e., the global server urlib.net need not be triggered).
Observation 1: The above "magic" works because the SO (containing this page) and the DOs of the hyperlinks have been deposited in federated Archives (Digital Repositories - Data Providers), all hosted in a special computational platform called URLib and thereby, parts of what is called the IBI network of Archives. Each of these Archives uses Uniform Resource Identifiers (URI) to identify their AIPs and operates as both a data provider and a local resolver for all the AIPs in the Federation. For this reason, it would be advantageous for the AIPs of any Archive be identified by URIs, should the Archive ever need to join a Federation.
Observation 2: It is sufficient for an Almost Fully Persistent Hyperlink (from a SO to a DO) to become a fully persistent hyperlink (from a SO to a DO) to ensure that the resolution doesn't depend on a global resolver, that is, it only depends on the resolution ability of the SO data provider itself.
Observation 3: The above two hyperlinks encoded in HTML work successfully in Firefox, Chrome and Edge, but at the moment the only drawback is that they only work in Firefox when encoded in PDF.
A next note introduces yet another definition of hyperlink, the so-called robust hyperlink, which is the last stage of the proposed advanced hyperlink types and contributes to solving the problem of the continued existence of Web resources [4].
‡ To resolve a DOI identifier, a copy of the corresponding Data Object of the destination AIP must have been inserted somewhere in the Federation and the Provenance Information in its AIP must describe the original DOI. The DOI hyperlink in the source AIP is considered fully persistent because in the event of a failure of the DOI resolver (doi.org), it returns a copy of the corresponding Data Object via a fully persistent hyperlink pointing to the copy identified in the IBI namespace.