Jump directly to the page contents

PIDA - Persistent Identifiers for Digital Assets

We provide long-lasting references for digital assets accessible to humans and machine agents


Frequently Asked Questions


What is a PID - and what does a PID do?

PID stands for "Persistent Identifier", which is, in case of PIDA PIDs are functionally a URLs. Instead of pointing directly to the location of an Internet resource, a PID points to an intermediate resolution service. The resolution service associates the PID with the actual URL/IRI and returns that URL/IRI to the client, which can then complete the transaction in the normal fashion.

Why do we need PURLs?

Link rot is a very common phenomenon - each and everyone of us has experience the “404-error” on the web before: Sometimes URLs do not work because Internet resources move, change names or method of access. Once a URL fails, all instances that link to that URL (for example, links in a Web document or a bibliographic record) become invalid. By using an intermediate resolver - like PIDA - broken links can quickly be repaired by registering the actual/new URL of the resource with the resolver.

What can my PID point to?

PIDs in PIDA can point to any resource on the Web identified by a URL.

What does a PID provided by PIDA look like?

PIDs look just like URLs because they are URLs. A PID has three parts:

  1. Protocol - The protocol used to access the PURL resolver. Note: This protocol may differ from that used to access the resource associated with the PID.
  2. Resolver address - The IP address or domain name of the PURL resolver. This portion of the PID is resolved by the Domain Name Server (DNS).
  3. Name - User-assigned name. Note: This name may differ from the name of the resource in the associated URL.

How do I create a PID in PIDA?

There are three ways to create a new PID in PIDA - please refer to the instructions which can be found here.

Is it possible to change the web resource URL in an already registered PID?

Yes, your data is stored in the PIDA GitHub repository. Records for existing PIDs may be modified by modifying your resource entry in your .htaccess file in the PIDA GitHub repository .

Are PIDs updated automatically when their associated URL changes?

No. The registrer of the PURL take the responsibility of updating thier PIDs when the associated URL changes.

What are some examples of PIDs from PIDA?

The root URL for all PIDA PIDs is https://purls.helmholtz-metadaten.de/. Each PID has the form https://purls.helmholtz-metadaten.de/[prefix]/[subdirectory]. For example, https://purls.helmholtz-metadaten.de/seo is a PID for the scientific events ontology.

Does a PID have the same associated URL forever?

No. It is the responsibility of a PID's owner and its maintainers to update the PID when the associated URL changes. The associated URL can be changed any time.

For how long is this service guaranteed to be maintained? How long can I expect my registered IRIs to be resolvable?

All data is is stored in the PIDA GitHub repository. The PIDA domain is hosted by a research center of the Helmoltz Association. Both of these infrastructures are highly reliable. We have considerable knowledge and experience in building PID services. We commit to maintain this service as it grows over the next 10+ years. In the highly unlikely event that PIDA will have to close operations, we guarantee that we will migrate all content to other suitable repositories so that your data will not be affected.

Is the communication with PIDA secured?

PIDA uses HTTPS communication protocol to protect the integrity and confidentiality of data between clients and the service. This is especially important for systems that require high levels of security, such as those in the financial, medical, and public infrastructure sectors.

Who can use this PIDA?

The PIDA service is open to everyone. It is intended to support and facilitate the findability and accessibility of research data from within the Helmholtz Association on the Web. We reserve the right to reject registered IRIs when used inappropriately.

How much does it cost to register an IRI? Will associated costs ever change?

The use of PIDA - registering and resolving IRIs is and will be free of charge.

Who is maintaining PIDA?

PIDA is provided to you and maintained by the Institute for Materials Data Science and Informatics (IAS-9) of the Forschungszentrum Jülich GmbH on behalf of the Helmholtz Metadata Collaboration (HMC). For questions and suggestions you can contact us via Contact us .