Persistent hyperlinks are important because they solve the problem that results from the relocation of web resources. However, other problems must be solved to ensure full persistence. One is the dependence, in some circumstances, on a global resolver and a URL scheme, another is the very existence of the Web resources.
Solutions to the above dependency are presented in [1] and [2] along with definitions and examples of Persistent Relative Hyperlinks and Fully Persistent Hyperlinks, respectively.
This note introduces yet another definition of hyperlink, which we call Robust Hyperlink, representing the last stage of the proposed advanced types of hyperlink and contributing to solving the problem of the continued existence of Web resources.
A summary of hyperlink maturity levels, including the Robust Hyperlink introduced in this note, is provided in Table 1.
Table 1 - Persistent hyperlink maturity levels
| URI type |
URI property | Res. level1 |
Safe DO2 |
Hyperlink name type |
Maturity level |
Hyperlink example |
|---|---|---|---|---|---|---|
| locator | protocol dependent server name dependent location dependent |
0 | location dependent absolute |
Ad-hoc | https://www.clir.org/wp-content/ uploads/sites/6/ pub63watersgarrett.pdf |
|
| locator | protocol dependent server name dependent location independent |
1 | persistent absolute |
Basic | https://doi.org/10.1016/j.rse.2021.112667 | |
| name | protocol independent server name independent location independent |
2 | persistent relative [1] relative |
Procedure driven |
ibi:8JMKD3MGP3W34R/44C25PS | |
| name | protocol independent server name independent location independent |
3 | fully persistent [2] relative |
Trust- worthy |
upn:3Q3U5H8:8JMKD3MGP3W34R/44C25PS | |
| name | protocol independent server name independent location independent |
3 | ✓ | robust relative |
Future facing |
Presently, any fully persistent hyperlink in a Web resource pointing to an IBI identified Web resource, both resourses hosted on the URlib platform [3]. |
1 Resolution level ::
0: no resolution;
1: global resolver;
2: browser resolver, Source Resolver and global Destination Resolver;
3: browser resolver, Source Resolver and local Destination Resolver.
2 Safe Destination Object (DO) [2] :: see Observation 4 below.
It is not uncommon for a digital object (information item) to be composed of parts of other digital objects distributed over the Web. This approach, based on the relevant principle of Single source of truth that provides data that are authentic and refenceable, guarantees the authenticity of the reused data and, consequently, prevents its deliberate or unintentional distortion.
To preserve in the Long-Term, that may extend indefinitely, the integrity of such digital object, and those that simply make references to other resources, the Robust Hyperlinks are specially important.
Taking advantage of how Source Objects [2] are stored in the file system when using the URLib platform [3], this note itself is an application of Robust Hyperlink's ease of use for building a gallery of authentic images (see the Examples Section below).
– A Robust Hyperlink (from a Source Object - SO to a Destination Object - DO is a Fully Persistent Hyperlink (from the SO to the DO)[2], which, when activated, increments a counter in the DO's Context Information that documents the number of times it has been activated from that particular SO.
– A Robust Hypertext is a hypertext whose hyperlinks are robust.
– URLib is the acronym for Uniform Repository for a Library, an experimental computing platform [3] that makes hosting of robust hypertext much easier and more secure because the IBI Identifier of the Source Object, specifically, its uniform repository name‡, is part of its storage path.
– doc is the standard name of a directory containing a hypertext (digital object) (see illustration in Fig. 1).
Figure 1. A doc directory.
Source: [4]
– A Uniform Repository (or package) is a set of 4 successive directories that forms a unique persistent path to a doc directory (see illustration in Fig. 2).
Figure 2. Example of a uniform repository.
The repository name is: dpi.inpe.br/ronei/1996/11.20.18.56
Source: [4]
When convenient, a repository is represented like a single directory (see illustration in Fig. 3).
Figure 3. Convention.
A repository R1
Source: [4]
– col is the standard name of a directory containing a local collection of uniform repositories stored in an Archive (see illustration in Fig. 4).
Figure 4. A col – local collection – directory.
A local collection col with two repositories R1 and R2.
Source: [4]
– The global collection is the set of local collections from Federated Archives (see illustration in Fig. 5).
Figure 5. The global collection.
. . . . .
The set of all interoperable local collections forms the overall collection of a Federation.
Source: [4]
This HTML page is an example of Source Object, it is a digital object using Robust Hyperlinks to incorporate parts of two other digital objects†. The two incorporations below are solved without the need of the IBI global Destination Resolver urlib.net [1] and use instead the UPN Local Destination Resolvers [2].
- First incorporation
- Observation 1 (About the source code):
• The hyperlink consists of a relative URL: the src attribute value contains neither the URL scheme nor the resolver domain name;
• The name upn:E8KGRE is the URI Namespace Prefix;
• The name 83LX3pFwXQZeBBx/65ij is the IBI Identifier of the Destination Object (DO) in the opaque namespace‡;
• vestiges is a directory name in the doc directory of the Destination Object (DO);
• urlibServicePage1995.pdf, in the vestiges directory, is the file name to be displayed;
• ibiurl.backgroundlanguage=en (optional) ensures that the horizontal bar menu above the displayed PDF, will be written in english;
• shortmenu=yes is to display a shorter horizontal bar menu. - Observation 2 (Matadata and Context Information):
The horizontal bar menu above the displayed PDF is part of the display of the DO. It indicates the IBI of the DO (shown as a tooltip text), its state (here the DO is the original), the license (here CC BY-NC-ND), its Metadata and, finally, a link to a list of the files that comprise the DO (one can verify in this list, the presence of the file vestiges/urlibServicePage1995.pdf been displayed below the horizontal menu).
The Context Information in the Allied Materials Area of the Metadata page (see Fig. 7), shows the value of the Citing Item List field. This field is automatically updated and contains the repository name urlib.net/www/2023/12.25.14.57 of the SO (this page). On the right is the counter showing the number of times the DO has been accessed from the SO (this page), this includes the PDF incorporation display and any click onto the anchor <upn:E8KGRE:83LX3pFwXQZeBBx/65ij> of [5] in the References.
Figure 7. Screenshot of the Citing Item List of DO 83LX3pFwXQZeBBx/65ij (see red arrow that points to the SO repository name urlib.net/www/2023/12.25.14.57) – Screenshot taken on July 1st, 2025.
- Observation 3 (Browser resolution):
The path of this HTML page from the col directory is col/urlib.net/www/2023/12.25.14.57/doc. The moment it is loaded in the browser, the relative hyperlink in the src attribute of the iframe tag is activated and the browser resolves it, leading to the URL: upn:E8KGRE:83LX3pFwXQZeBBx/65ij/vestiges/urlibServicePage1995.pdf?ibiurl.backgroundlanguage=en&shortmenu=yes.
- Observation 4 (Transmission of the citing item Identifier and Context Information update):
When this URL is executed by the Source Resolver, the part of the information it contains that consists of the repository name urlib.net/www/2023/12.25.14.57 of the SO, i.e. its Identifier, is passed to the Destination Resolver which can then updates the Context Information of the DO with the information that an SO (in this case, the SO with repository name urlib.net/www/2023/12.25.14.57) has once again requested the DO or part of it.
- Observation 5 (Item removal blockage):
Once the Context Information of the DO has been updated with the information that at least one SO has requested the DO or part of it, the URLib platform delete manual procedure of the DO is automatically disabled as shown in Fig. 8, preventing deliberate or unintentional removal of the DO and thus making it safe.
Figure 8. The Delete Button (see lower red arrow) is disabled while the DO with IBI 83LX3pFwXQZeBBx/65ij (see upper red arrow) has at least one citing item (see Fig. 7).
- Observation 6 (Context Information update in case of a SO removal):
If, for some reason, the SO (this page) is deleted from the URLib platform, then the value of the Citing Item List field of the DO metadata will be automatically updated removing the SO from the citing item list.
- Second incorporation
Figure 9. Incorporation of a bar chart and a link to the Metatada of its original digital object.
Incorporation source code for the bar chart: <img src="./upn:RFF2E5-:8JMKD3MGPCW/3HHLNUH/thesisVivaPublicationYearBar.jpg">
Source code to access the Metadata: <a href="./upn:RFF2E5-:8JMKD3MGPCW/3HHLNUH:?ibiurl.backgroundlanguage=en">Metadata</a>
- Observation 7 (About the source codes):
• The hyperlinks are relative URLs: the values of the src and href attributes don't contain the resolver domain name;
• The name upn:RFF2E5- specifies the identification namespace. The hyphen (-) after the word ibi means to display the bar chart and the metadata without the horizontal menu bar;
• 8JMKD3MGPCW/3HHLNUH is the IBI Identifier of the Destination Object (DO) in the opaque namespace‡;
• thesisVivaPublicationYearBar.jpg in the first source code is the file name to be displayed;
• : (colon) after the Identifier, in the second source code, indicates that the metadata of the digital object will be returned.
• ibiurl.backgroundlanguage=en (optional) ensures that the metadata will be written in english. - Observation 8 (Importance of the Robust Hyperlinks):
The Robust Hyperlinks (from a Source Object - SO to a Destination Object - DO) can significantly contribute to solving the problem of the DO's continued existence in the sense that, based on the DO's Context Information that there is a digital object, precisely a SO, citing the DO, it is possible to disable any attempt to remove the DO and, in this way, preserve the hyperlink functionality.
- Observation 7 (About the source codes):
Figure 6. Incorporation of a PDF page with its menu bar at the top.
Source: [5]
Incorporation source code: <iframe src="./upn:E8KGRE:83LX3pFwXQZeBBx/65ij/vestiges/urlibServicePage1995.pdf?ibiurl.backgroundlanguage=en&shortmenu=yes"></iframe>
References
[1] BANON, G. J. F. Example of three Persistent Relative Hyperlinks. [S.l.] Deposited in the URLib collection, 2023. IBI: <QABCDSTQQW/49884CP>. Available from: <upn:EFDBHS:QABCDSTQQW/49884CP>.[2] BANON, G. J. F. Example of three Fully Persistent Hyperlinks. [S.l.] Deposited in the URLib collection, 2023. IBI: <QABCDSTQQW/4A86BJH>. Available from: <upn:E8KGRE:QABCDSTQQW/4A86BJH>.
[3] BANON, G. J. F. What is URLib?. [S.l.] Deposited in the URLib collection, work-in-progress. IBI: <LK47B6W/E6H5HH>. Available from: upn:9HFNHE:LK47B6W/E6H5HH.
[4] BANON, G. J. F. Uniform repositories for a digital library - URLib. [S.l.] deposited in the URLib collection, 1998. An earlier version of this work has been presented at the VI Seminário sobre Automação em Bibliotecas e Centros de Documentação, September 9-10, 1997, Águas de Lindóia, SP, Brazil. IBI: <83LX3pFwXQZeBBx/aa6dE>. Available from: <upn:EEU3D2:83LX3pFwXQZeBBx/aa6dE>.
[5] BANON, G. J. F. Uniform Repository Service Version 1.1. [S.l.] deposited in the URLib collection, 1998. IBI: <83LX3pFwXQZeBBx/65ij>. Available from: <upn:E8KGRE:83LX3pFwXQZeBBx/65ij>.
[6] PEREIRA, C. M.; BANON, G. J. F. Breve relatório referente ao ano de 2014 com dados oriundos da Memória Científica do INPE. São José dos Campos: INPE, versão: 2014-12-26. IBI: <8JMKD3MGPCW/3HHLNUH>. Available from: <upn:RFF2E5:8JMKD3MGPCW/3HHLNUH>.
[7] COMISSÃO-DE-ESTUDOS ABNT/CB08/SC010/CE70. System for IBI generation. São José dos Campos: Comissão-de-Estudo ABNT/CB08/SC010/CE70, version: 2021-11-14. 48 p. IBI: <J8LNKB5R7W/3NSP3DL>. Available from: upn:32NSFRP:J8LNKB5R7W/3NSP3DL.