==About the Learning Object==

This Learning object deals with Persistent identifiers (PIDs).
It is divided into 17 sub-units each of which consists of two parts: a dialogue between two owlets (on the left of the screen) introducing PIDs, and a video (on the right of the screen) representing the concepts.

The idea was to use the famous painting by Botticelli, The Birth of Venus, as a metaphor. Each PID functional requirement is represented by a visual metaphor associated with a musical metaphor: uniqueness, persistency, resolvability, reliability, authoritativeness, flexibility, interoperability and cost effectiveness.

==01 - Introduction==

>> First character:
"There was a great exhibition by Sandro Botticelli in Florence only a few years ago. It was the first time so many of his works were collected in one place and I remember reading very positive reviews about it.
But ... I can't find the information about this event any more ... I type the correct URL and what I get is '404: not found'. It is so annoying considering the event is so recent. I wonder what we'll find in ten years' time."

>> Second character:
"You wouldn't have this problem if Persistent identifiers had been used to refer to that exhibition!"

>> First character:
"Persistent? What are you talking about? Everything is so volatile nowadays ... anyway, what do you mean by 'Persistent Identifiers'?"

==02 - Global uniqueness==

>> First character:
"Are PIDs really necessary?"

>> Second character:
"What if we couldn't rely on '''globally unique''' identifiers?"

==03 - Persistence==

>> Second character:
"What if we couldn't rely on '''permanently unique''' identifiers?"

==04 - Resolvability==

>> Second character:
"What if identifiers weren't linked to the current location of the resources?"

==05 - Reliability==

>> Second character:
"What if we couldn't be supported by a '''reliable''' PID system?"

==06 - Authoritativeness==

>> Second character:
"What if we couldn't rely on an '''authoritative''' PID system?"

==07 - Flexibility==

>> Second character:
"What if a PID system did not represent collections in sufficient '''detail'''?"

==08 - Interoperability==

>> Second character:
"What if we couldn't rely on a '''interoperable''' PID system?"

==09 - Cost-effectiveness==

>> Second character:
"What if we couldn't rely on an '''affordable''' PID system?"

>> First character:
"What a mess! What happened?"

>> Second character:
"Don't worry, you can use PIDs!
PIDs can refer to all the information associated with a real object, including its location, or to any of its potential surrogates, e.g. digital images, a museum collection where it belongs, research documents referring to it and other services.
PIDs may be applied to real objects as well as to more abstract concepts like services, transformation issues, aggregation or disaggregation of objects and organizations."

==10 - Cost-effective==

>> Second character:
"Due to limited funding allocated to the cultural heritage sector, cultural organisations should use PID systems that are either free or have very low costs"

===Cost effective===
Resources, particularly financial resources, are scarce in the cultural heritage sector.
In addition, organisations have a general mission to provide access to their items free of charge for non-commercial use.

Therefore:
Cultural organisations should use PID systems that are either '''free''' of charge, or have a very '''low''' cost in relationship to their available resources.
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==11 - Interoperable==

>> Second character:
"To enable the greatest number of users to share and use cultural contents, '''interoperability''' among different PID systems must be achieved mainly through the adoption of '''open standards'''."

===Interoperable===

This is vital to ensuring that cultural content can be shared and used by as a large a set of users as possible.
Many PID solutions were designed for specific domains.
Therefore:
Organisations should use intellectually openstandards for the implementation of PIDs.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==12 - Flexible==

>> Second character:
"An identifier system should adjust to different requirements of different types of collections, for example it should be able to deal with varying levels of details, from individual objects to aggregations: the granularity of collections should be represented. This is called '''flexibility'''."

===Flexible===

A PID system will work more effectively if it can handle the requirements of different types of collections.
Parts of collections may be curated at different levels of 'granularity', from parts of objects, to individual objects, to collections objects. The latter has an unbounded number of individual elements.

Therefore:
Organisations should use PIDs systems that are flexible enough to represent the granularity of their collections.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==13 - Authoritative==

>> Second character:
"Organisations should establish the '''authority''' and credibility of a PIDs system's provider before adopting that system."

===Authoritative===

Some PID systems are dependent on responsible organisations who: manage the system, assign identifier; and resolve the identifiers to resources.
Some services are provided by public institutions like national libraries and archives.
For a system to be effectively supported the responsible organisation must be able to demonstrate its commitment.

Therefore:
Organisations should evaluate and be assured of the authority and credibility of a PIDs system's provider before adopting that system.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==14 - Reliable==

>> Second character:
"The '''reliability''' of PID systems should be certified by institutions by means of redundant technology and register updates (preferably automatic)."

===Reliable===

For a PIDs system to function reliably these issues have to be assessed:

*1. It should always be active (e.g. backed up, with redundant technology)
*2. The register of PIDs should be updated (preferably automatically)

Therefore:
Organisations should evaluate and be assured of the technical reliability of a PID system (including their own) before adopting it.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==15 - Resolvable==

>> Second character:
"Yes you are! As a matter of fact '''resolution''' services guarantee that PIDs are linked to their current resource URLs even when the latter change.
So, don't mix up resolution with retrieval, which is the ability of systems to access and download digital resources by clicking on URLs."

===Resolvable===

Choice to use PIDs does not imply that an external human user will be able to access anything that they can use effectively.

Therefore:
Organisations should be clear, and make public, information about which, if any, their PIDs resolve to an available resource.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==16 - Persistent==

>> Second character:
"You see, '''persistence''' refers to a number of aspects which are not only technical, but also related to the policies and commitments of institutions. They should be committed to creating and maintaining their PIDs in order to give exhaustive information about their collections, no matter what."

===Persistent===

Persistence refers to the lifetime of an identifier, during which it should not possible to reassign it to another resource or to delete it.
If an organisation can guarantee that a PID will be managed so that it will survive changes to ownership and PID system, then an external user can be confident of its persistency.

Therefore:
Organisations should commit themselves to the persistence of their PIDs and make clear to others what they mean by 'persistent' and how this will be implemented.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==17 - Uniqueness==

>> Second character:
"A PID is a label associated with something in a particular environment. On the Internet it should be '''globally unique''', but it may only be so within a specified context. At any rate, it must be unique within the institution's own system."

>> First character:
"Oohhh, what a masterpiece!"

===Uniqueness environment===

A PID is label that is associated with something in a particular environment. On the Internet it should be globally unique, but may only be unique in combination with a limited name space. In the 'worse' case it may only be unique within an organisation's own systems.

Therefore:
Organisations should be clear, and make public, in which environment their PIDs are unique.'''
[Persistent Identifiers (PIDs): recommendations for institutions, by Gordon McKenna and Roxanne Wyns.]

==18 - Conclusions==

Thank you for viewing our Learning Object "Persistent Identifiers: What if?"

We invite you now to answer some questions for your learning assessment (https://elearning.unipd.it/moodle1/mod/quiz/view.php?id=23811) and to give us your feedback about the Learning Object by evaluating its quality with Evaluate this Learning Object: "PIDs: What if" (https://elearning.unipd.it/moodle1/mod/feedback/view.php?id=23797).

For further details:

Readings and training materials (https://elearning.unipd.it/moodle1/mod/book/view.php?id=23574&amp;chapterid=53)

==19 - Credits==

Project by:

Cristiana Bettella
Elena Bianchi
Lisetta Dainese
Massimo Ferrante
Michele Visentin
Antonella Zane
CAB, University of Padua (Italy)

Texts based on the Athena project booklet "Persistent Identifiers (PIDs): recommendations for institutions" by Gordon McKenna and Roxanne Wyns.

Graphic design by Gianluca Drago
CAB, University of Padua (Italy)

Technical support and Flash development by Angelo Calò, Cecilia Dal Bon
CMELA, University of Padua (Italy)

Audio by Lodovico Bollacasa, Padua (Italy)

Music from:

Wolfgang Amadeus Mozart, "Piano Sonata No.16 in C major, K.545, "Sonata facile""
Sergej Sergeevi&#269; Prokof'ev, "Peter and the Wolf"
Frederic Chopin, "Valtz in A flat Major op.69 n.1"
Lodovico Bollacasa, "Petite fille"

Acknowledgments:

We would like to thank Andrea Belli, Valeria Donata Bettella and Lodovico Bollacasa (Milan – Padua, Italy) for the interoperability images, and the pianist Ugo Armano (Padua, Italy) for performing Mozart's "Sonata facile".

This work by Linked Heritage project is licensed under a <a href="http://creativecommons.org/licenses/by-nc-sa/3.0/">Creative Commons Attribution Non-Commercial Share Alike License (CC-BY-NC-SA)</a>.

Funded by the Competitiveness and Innovation Framework Programme, 2011.
