PID-LAND is a PID-centric resolver and landing service designed to provide persistent, FAIR, and provenance-aware access to seismological waveform data.
At its core, PID-LAND adopts an information-centric architecture: a Persistent Identifier (PID) does not identify a file, a URL, or a backend service, but a conceptual digital object. This conceptual object represents the scientific meaning of the data—independent of how, where, or in which format the data are stored.
From a single PID, multiple representations of the same object can be resolved in a controlled and coherent way, including data, metadata, provenance records, and aggregated dataset views.
In PID-LAND, a conceptual digital object is a logical entity that represents a waveform dataset as a scientific object, rather than as a physical file.
A conceptual digital object:
- exists independently of storage layout or delivery mechanisms
- remains stable across file migrations, format changes, or infrastructure evolution
- can be resolved into different representations depending on the user or machine request
This distinction between what the object is and how it is materialized is fundamental to long-term persistence, interoperability, and reproducibility.
A PID identifies the concept; representations are views of that concept.
PID-LAND exposes a single, stable public resolver endpoint:
https://hdl.handle.net/<prefix>/<pid>
The PID (<prefix>/<pid>) always refers to the same conceptual digital object. It never encodes:
- file paths
- storage locations
- backend services
- access protocols
While hdl.handle.net provides a universal, public entry point, all actual data and services are hosted on the project infrastructure (e.g., https://my-resolver.net).
The PID manager stores the mapping between the PID and the internal project URL. When a user resolves the PID via hdl.handle.net, the resolver performs a redirect to the project-specific endpoint:
User -> https://hdl.handle.net/<prefix>/<pid> -> PID-LAND resolver -> redirect -> 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 conceptual 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.
PID-LAND exposes FAIR Digital Objects through an OAI-PMH interface for scalable metadata harvesting.
http://<resolver>/oai?verb=...
- Identify
- ListIdentifiers
- ListRecords
- GetRecord
- ListMetadataFormats
- Dublin Core metadata (oai_dc)
- resumptionToken pagination
- globally resolvable identifiers (PID-based)
- machine-readable guidance via Identify/description
OAI-PMH records are a projection of WF-Handle metadata, not an independent representation.
Core fields are mapped as follows:
| WF-Handle | OAI_DC |
|---|---|
| dc:identifier | dc:identifier |
| dc:title | dc:title |
| dc:creator | dc:creator |
| dc:publisher | dc:publisher |
| dc:subject | dc:subject |
| dc:date | dc:date |
| dc:format | dc:format |
| dc:type | dc:type |
| dc:rights | dc:rights |
| version | dc:relation |
| provenance link | dc:relation |
| document link | dc:relation |
| temporal | dc:coverage |
| spatial | dc:coverage |
OAI-PMH provides a simplified, interoperable metadata view, while full representations remain accessible via PID resolution.
Links to advanced representations are exposed through:
dc:relation → ?urlappend=?q=metadata
dc:relation → ?urlappend=?q=provenance
dc:relation → ?urlappend=?q=document
OAI-PMH enables discovery; PID-LAND enables full access.
This request
http://<resolver>/oai?verb=GetRecord&identifier=oai:ingv:<pid>&metadataPrefix=oai_dc
retrieve this
<record>
<header>
<identifier>oai:ingv:11099/b89bd40c-aaf3-11ee-ad3c-0242ac120013</identifier>
<datestamp>2024-01-04</datestamp>
</header>
<metadata>
<oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/">
<dc:title>INGV mSEED Repository</dc:title>
<dc:creator>INGV ITALY</dc:creator>
<dc:publisher>EIDA ITALIA</dc:publisher>
<dc:contributor>network operator</dc:contributor>
<dc:subject>mSEED, waveform, seismic data</dc:subject>
<dc:description>Seismic waveform data managed as FAIR Digital Objects</dc:description>
<dc:date>2024-01-04</dc:date>
<dc:identifier>https://hdl.handle.net/11099/b89bd40c-aaf3-11ee-ad3c-0242ac120013</dc:identifier>
<dc:format>application/vnd.fdsn.mseed</dc:format>
<dc:type>Dataset</dc:type>
<dc:rights>https://creativecommons.org/publicdomain/zero/1.0/</dc:rights>
<!-- version -->
<dc:relation>version:0</dc:relation>
<!-- metadata -->
<dc:relation>
https://hdl.handle.net/11099/b89bd40c-aaf3-11ee-ad3c-0242ac120013?urlappend=?q=metadata
</dc:relation>
<!-- provenance & versions -->
<dc:relation>
https://hdl.handle.net/11099/b89bd40c-aaf3-11ee-ad3c-0242ac120013?urlappend=?q=provenance
</dc:relation>
<!-- documentation -->
<dc:relation>
https://hdl.handle.net/11099/b89bd40c-aaf3-11ee-ad3c-0242ac120013?urlappend=?q=document
</dc:relation>
<!-- temporal coverage -->
<dc:coverage>2024-01-03T00:00:00.000000Z/2024-01-03T23:59:59.990000Z</dc:coverage>
<!-- spatial coverage -->
<dc:coverage>lat=41.631801 lon=15.90782 alt=30.0</dc:coverage>
</oai_dc:dc>
</metadata>
</record>
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.
WF Handle is a JSON Schema designed to describe Information-centric metadata for waveform digital objects.
It represents the information core of the PID-LAND architecture and provides a machine-actionable, FAIR-compliant description of waveform digital objects, independently of storage systems or delivery services.
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.
It is a core component of the PID-LAND ecosystem and complements the WF Handle schema by providing a structured, machine-actionable description of data lineage, versioning, and processing history.
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 data ,specially of miniSEED the current data format used.
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 conceptual dataset defined by a query, rather than by a pre-existing file.
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.
Special PIDs represent query-defined datasets.
https://hdl.handle.net/11099/wf-search?urlappend=?q=/lat/.../lon/.../start/.../end/.../asof/...
They enable:
- reproducible dataset extraction
- time-aware queries (asof)
- persistent identification of dynamic data
- Machine-Actionable by Design
All outputs are:
- JSON-LD
- JSON Schema validated
- SHACL constrained
in summary PID-LAND enables:
- persistent identification of conceptual objects
- multiple coherent representations
- scalable metadata harvesting via OAI-PMH
- reproducible and machine-actionable data access
It bridges discovery (OAI-PMH) and resolution (PID-LAND) in a unified, FAIR-compliant architecture.
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/asof/2025-01-01
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/asof/2025-01-01
Resolves to a deterministic dataset view, suitable for reproducible scientific workflows.
PID-LAND demonstrates how persistent identifiers can act as stable entry points to conceptual digital objects, enabling multiple coherent representations, query-defined persistent datasets, and provenance-aware, machine-actionable access. All of this is achieved without exposing internal storage, backend services, or infrastructure details, making PID-LAND robust and portable across ecosystems.