Technical Specifications

Secured Communication

PIDA uses HTTPS communication protocol to protect the integrity and confidentiality of data between clients and the service. This is especially important for systems and applications that require high levels of security, for example, when managing biomedical datasets.

Content Negotiation

PIDs from PIDA can redirect to any kind of resource on the web (i.e., HTML or something else). However, PIDA is capable of content negotiation which is widely utilised by semantic web systems. It enables the delivery of different representations of a resource from a single uniform resource identifier (URI). When a user or agent requests a URI, he/she can specify which representation is required (e.g., document language, file format, or content encoding).

Using a PIDA PID, clients can request either HTML or RDF (with different RDF serializations) representations. However, requests to PIDs that are coming from non-semantic web applications will be redirected to HTML documents, while those that are coming from designated semantic web applications will be redirected to RDF documents. Content negotiation for a given PID can be enabled by the user by adding the required information to the submitted .htaccess file.

Testing

Content negotiation can be tested using the curl command-line utility to specify a particular representation of a resource to the same URI. For example:

To request the HTML document describing the scientific events ontology:

curl -L -H "Accept: text/html" https://purls.helmholtz-metadaten.de/seo

To request the RDF file of the ontology, the following command could be used

curl -L -H "Accept: application/rdf+xml"  https://purls.helmholtz-metadaten.de/seo

You will get results that look like:

HTTP/ 1.1 303 See Other
Date: Tue, 22 Feb 2022 14:18:54 GMT
Server: Apache/2.4.29 (Ubuntu)
Access-Control-Allow-Origin: \*
Location: https://saidfathalla.github.io/.../index.html
Content-Type: text/html; charset=iso-8859-1

Windows users can get cURL binaries from here.