PID-LAND represents the visible layer of a FAIR Digital Object-Oriented Data Center (FDO-ODC):
an ecosystem where Persistent Identifiers resolve FAIR Digital Objects into machine-actionable information services rather than simply locating digital resources.
PID-LAND is an Information Representation Engine that transforms Persistent Identifier resolution into the materialization of context-aware representations of FAIR Digital Objects.
Rather than simply locating digital resources, PID-LAND provides machine-actionable access to multiple coherent representations — including metadata, provenance, waveform data, documentation, citable references, and future domain-specific representations — while preserving the identity of the underlying FAIR Digital Object.
Each representation exposes a different view of the same FAIR Digital Object.
The information remains persistent.
Representations are materialized on demand.
Note
The repository is currently undergoing an internal architectural refactoring that introduces the concepts described in this document (PRISM, Palette, Hues and Modules).
The public interfaces and the underlying concepts remain unchanged; the ongoing work focuses on improving the internal organization of the implementation.
Traditional PID resolution follows a resource-centric model.
PID
│
▼
URL
│
▼
Resource
PID-LAND adopts a representation-centric approach.
PID
│
▼
FAIR Digital Object
│
▼
PRISM Representation Engine
│
├── Metadata
├── Provenance
├── Waveforms
├── Citations
├── Documentation
└── Future Representations
A single PID.
Multiple coherent representations.
One FAIR Digital Object.
PRISM builds upon the FAIR Digital Object model to explain how a FAIR Digital Object may expose multiple independent representations.
It explains, moreover, how the information associated with a FAIR Digital Object remains stable while its representations evolve independently.
Within PID-LAND:
- a PID identifies a FAIR Digital Object;
- the associated information remains persistent;
- representations are materialized according to the requested context.
Representations may differ in:
- purpose;
- format;
- level of abstraction;
- delivery protocol.
The identity of the FAIR Digital Object never changes.
Only its representations evolve.
A PID identifies a FAIR Digital Object.
PRISM materializes context-aware representations of FDO.
PID-LAND exposes a single, stable public resolver endpoint:
https://hdl.handle.net/<prefix>/<pid>
The PID (<prefix>/<pid>) always identifies the same FAIR Digital Object.
It never encodes:
- file paths
- storage locations
- backend services
- access protocols
- representation formats
While hdl.handle.net (or other global resolver) provides a universal, public entry point, all actual data and services are hosted on the project (local) infrastructure with specific endpoint (e.g., https://my-resolver.net).
When a user resolves the PID via hdl.handle.net (or other global resolver), the resolver performs a redirect to the project-specific endpoint:
User -> https://hdl.handle.net/<prefix>/<pid> -> redirect to -> PID-LAND (local resolver) -> https://my-resolver.net/<prefix>/<pid>
This approach ensures:
- The PID remains persistent and stable.
- The underlying storage, service, or protocol can change without breaking the PID.
- Users always access the FAIR digital object without needing to know internal infrastructure details.
Traditional data services often adopt a system-centric approach, where identifiers are tightly coupled to specific services, storage locations, or representations. This typically leads to:
- Different URLs for data, metadata, and provenance
- Fragmentation of identifiers
- Reduced long-term persistence and interoperability
PID-LAND deliberately follows an information-centric approach, where the PID is the stable reference and systems and services are interchangeable. Representations can evolve without breaking identifiers and independent of:
- Storage backends
- File paths
- Software components
- Representation formats
This design aligns with established PID infrastructures (Handle, DOI) and extends them toward FAIR Digital Objects.
PID-LAND implements a clear resolver contract: different representations are obtained by specifying the requested view through the urlappend parameter.
| Resolution request | Resulting representation |
|---|---|
<prefix>/<pid> |
Default view (latest dataset state) (MSEED) |
<prefix>/<pid>?urlappend=?q=metadata |
WF Handle metadata (JSON-LD) |
<prefix>/<pid>?urlappend=?q=provenance |
WF Provenance record (JSON-LD) |
<prefix>/<pid>?urlappend=?q=version=<n> |
Specific historical version (MSEED) |
<prefix>/<pid>?urlappend=?q=document |
Human readble documentation (TXT) |
<prefix>/wf-search?urlappend=?q=... |
Aggregated dataset (WF-Manifest, RO-Crate) |
<prefix>/wf-select?urlappend=?q=... |
Deterministic dataset (WF-Manifest, RO-Crate) |
All views are resolved from the same identifier, ensuring semantic coherence between data, metadata, and provenance.
All representations—static or query-derived are selected using the same resolution mechanism:
<prefix>/<pid>?urlappend=<view>
Supported views include:
metadata→ WF Handleprovenance→ WF Provenancedata→ waveform files (default)document→ readable documentation
special pid
search→ WF-Manifestselect→ WF-Manifest
This uniform contract ensures that identifier semantics remain stable while representations evolve.
The seismological use case provides a practical example of how PID-LAND operates.
WF Handle is a JSON Schema designed to describe Information-centric metadata for waveform digital objects.
WF Handle focuses on what the data is, while complementary schemas WF Provenance describe how the data was produced.
Repository: https://github.com/INGV/wf-handle
https://hdl.handle.net/11099/be9b7af6-f71f-11ee-aae9-0242ac120004?urlappend=?q=metadata
WF Provenance is a JSON Schema designed to describe workflow-level provenance information for waveform digital objects.
The schema is intended for public use, automatic validation, and long-term traceability of waveform digital objects.
Repository: https://github.com/INGV/wf-provenance
https://hdl.handle.net/11099/be9b7af6-f71f-11ee-aae9-0242ac120004?urlappend=?q=provenance
In the seismological domain, the data component typically consists of timestamped ground motion samples stored in miniSEED (mSEED) format, a widely recognized standard within the International Federation of Digital Seismograph Networks (FDSN).
https://hdl.handle.net/11099/be9b7af6-f71f-11ee-aae9-0242ac120004
A human-readable description of the data, particularly the miniSEED format currently used for waveform distribution.
https://hdl.handle.net/11099/be9b7af6-f71f-11ee-aae9-0242ac120004?urlappend=?q=document
PID-LAND introduces the concept of Special PIDs, extending persistent identification beyond static datasets.
A Special PID identifies a query-defined dataset, rather than by a pre-existing stored object.
In this model:
- the selection logic defines the object
- the PID identifies that logic
- resolution materializes a dataset view
The query itself becomes a persistent, citable object.
Special PIDs are not API calls. They are persistent identifiers whose resolution produces a reproducible dataset derived from well-defined criteria.
A Special PID:
- represents a stable conceptual dataset
- resolves through the same PID-LAND endpoint
- produces a materialized dataset view
- maintains explicit links to WF Handle metadata and WF Provenance records
- remains machine-actionable and FAIR-compliant
Although resolution is dynamic, the identified object is conceptually stable.
Using: asof= 'date' the resolver reconstructs the state of datasets valid at a specific point in time, allowing reproducible retrieval even when underlying datasets evolve.
When a Special PID is resolved, PID-LAND generates a WF-Manifest, a structured dataset representation encoded as an RO-Crate JSON-LD.
The WF-Manifest:
- represents the output of a query-defined conceptual object
- aggregates waveform files as
MediaObjectentities - links each file to its metadata and provenance
- is fully machine-actionable and FAIR-compliant
WF-Manifest is not a separate service, but the natural consequence of resolving a Special PID.
Repository: https://github.com/INGV/wf-manifest
All resolver outputs are:
- encoded in JSON-LD
- validated with JSON Schema
- constrained using SHACL
This guarantees structural validity, semantic consistency, and seamless automation across workflows.
https://hdl.handle.net/11099/wf-search?urlappend=?q=/lat/40.7867/lon/15.9427/rad/10/start/2024-04-09/end/2024-04-10
Resolves to an aggregated RO-Crate manifest describing all matching waveform objects.
Typical use cases include regional discovery, event-based analysis, and automated data packaging.
https://hdl.handle.net/11099/wf-select?urlappend=?q=/net/IV/sta/ACER/loc//cha/HNE/start/2024-04-08/end/2024-04-10
Resolves to a deterministic dataset view, suitable for reproducible scientific workflows.
To independently assess the architectural and operational approach presented here, PID-LAND objects can be evaluated using the F-UJI Automated FAIR Data Assessment Tool, available here.
Simply copy one of the example PIDs above and paste it into the "Research Data Object (URL/PID)" field.
Rather than emphasizing the numerical FAIRness score itself, this assessment demonstrates that Persistent Identifiers within PID-LAND act as machine-actionable entry points to an information ecosystem whose FAIR characteristics can be objectively recognized by an independent assessment framework.
PID-LAND demonstrates how Persistent Identifiers can become stable entry points to FAIR Digital Object rather than to individual resources.
By separating FAIR Digital Objects from their possible representations, the same FAIR Digital Object can be materialized through multiple coherent views while remaining independent of storage systems, software components, transport protocols, and evolving technologies.
PID-LAND is powered by PRISM, an Information Representation Engine that separates execution mechanics from domain knowledge through the concepts of Palette, Hue, and reusable Modules.
The complete architectural design is described in:
- PRISM.md — Representation Engine Architecture
- BICYCLE.md — Design Philosophy
FAIR Digital Objects are intended to remain persistent while technologies continue to evolve.
Information is the long-lived asset. Technology is only its current vehicle.
Technology changes.
Information continues the journey.