by Gérald Jean Francis Banon
November 2023
Updated in December 2023
The need for long-term digital information preservation is the main concern of many initiatives, one of them is the development of the CCSDS and International Organization for Standardization (ISO) Reference Model for an Open Archival Information System (OAIS) [1].
One of the open preservation problem is how to maintain the integrity of hyperlinks in the Long-Term, that may extend indefinitely.
The purpose of this note is to illustrate the existence of a digital service oriented to a Federation of Archives that allows a persistent hyperlink working without the need of a global resolver.
This HTML page contains two Fully Persistent Hyperlinks, each one based on an Identifier within some specified namespace. The first one uses the IBI namespace and the second the DOI namespace.
This page is the Data Object (Digital Object) of an Archival Information Package (AIP) preserved in an Archive which is 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].
Currently, this Federation have the following members (the first is the one hosting the present HTML page): Furthermore, each federated global node acts as both a data provider and an IBI and DOI 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 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). That is, the digital procedure argument doesn't specify the resolver domain name, but it does specify the namespace type. In 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 proper SO data provider acting as a local resolver of the Federation, that is the resolution is done without the aid of a global resolver. In other words, the resolution process is not centralized, but distributed.
An example of two Almost Fully Persistent Hyperlinks is given in [2]. In the next section, an example of two Fully Persistent Hyperlinks is now given.
The two hyperlinks below are relative Persistent Hyperlinks‡. This can be checked by looking at the value of the respective href attibute in the source code of this HTML page.
They are Fully Persistent because the SO (i.e., the AIP containing this page) and the DO 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 of 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, all hosted in a special computational platform called URLib and thereby, parts of what is called the IBI network of Archives, each of which using the same namespace (here the IBI namespace [3]) and working as both a data provider and an IBI or DOI resolver for all the AIPs in the Federation. For this reason, it would be advantageous for the AIP identifiers to be Uniform Resource Name (URN) when an Archive 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 the global resolver, that is, depends only on the resolver ability of the SO data provider.
Observation 3: The long name fullypersistenthref which appears at the begining of the relative URL has been chosen in the URLib platform to avoid possible directory name conflict in the doc directory, since names like ibi and doi are used by the digital service of the platform to perform the correct translation of the ddo identifiers into currently valid ddo locations.
Observation 4: The above two hyperlinks coded in HTML work successfully with Firefox, Chrome and Edge, but at the present time the only downside is that they work only with Firefox when coded in PDF.
A next note introduces one more definition of hyperlink, the so-called Robust Hyperlinks that is the last stage of proposed advanced hyperlink types and contributes to solve the problem of the continued existence of the Web resources [4].
‡The objects involved in these hyperlinks should be interpreted as Archival Information Packages (AIPs).