About the Linked Data Repository (LDR)

Introduction

The Linked Data Repository (LDR) is a key component of Elsevier's Smart Content solution. The LDR solution provides a set of services and APIs for applications built by Elsevier and third parties to store and retrieve content enhancements and other forms of semantic metadata about both Elsevier content and content available in other resources published on the Web. The LDR stores the data as RDF documents and provides RESTful (REpresentational State Transfer) APIs for ease of integration and use.

The LDR metadata service manages data representing content metadata or knowledge models for controlled vocabularies. Metadata is stored in the LDR in the form of structured satellites, which are documents containing RDF statements describing a specified resource.

Content satellites represent metadata describing a content-related resource such as an article, book chapter, drug monograph, image, or video. Examples of metadata contained within a satellite may include the following:

  • Concept tags from a taxonomy for a given document
  • Document sections relevant to a given concept
  • Document sections providing answers to a given question
  • Relationships between concepts extracted from a given document
  • Concepts that are in the areas of expertise for a given author

Vocabulary satellites contain a knowledge representation of a specified controlled vocabulary.

The LDR can be queried by client applications with HTTP URI-based calls using a RESTful web API to provide users with smart content-related features such as enriched semantic search capabilities and vocabulary services. For example, a client application can use the LDR API to bulk-load the contents of a vocabulary, to query concepts within a vocabulary, or to find related sources linked to a specified entity.

LDR Vocabularies

Currently, the SciValFunders vocabulary can be accessed using LDR API calls.

SciValFunders Vocabulary

The SciValFunders vocabulary is provided in LDR to support the FundRef initiative that is being facilitated by CrossRef organization to provide a standard way of reporting funding sources for published scholarly research.

The source for the SciValFunders vocabulary is the hierarchical list of funding bodies that are available through Elsevier's SciVal Funding product. SciVal Funding is an online solution that provides targeted recommendations on grants, making it easier for researchers to discover funding opportunities related to their area of research. For more information about SciVal Funding, go to www.funding.scival.com.

SciValFunders Satellite Information Structure

Each funding body is represented by an entry in the SciValFunders vocabulary that includes the following properties for the funding body:

Property

Description

Concept ID

A unique identifier for the funding body.

Preferred Label The preferred label to use when referring to the funding body (for example, Massachusetts General Hospital).
Alternate Labels One or more alternate labels that are used for the funding body (for example, MGH).
Timestamps

Timestamps that indicate when the concept was created and last modified.

Timestamps are in the format:

yyyy-mm-ddThh:mm:ss

For example, 2012-05-04T23:58:30 indicates 4 May 2012 at 11:58:30 PM.

Funding Body Type

The funding type of the funding body.

Funding types include:

  • pri: Private
  • gov: Government
Funding Body Subtype

The funding subtype of the funding body.

Private funding subtypes include:

  • academic
  • corporate
  • foundation
  • international
  • other non-profit (private)
  • professional associations and societies

Government funding subtypes include:

  • federal (national government)
  • government non-federal (state/provincial government)
Country

The URI on the sws.geonames.org website for the ISO 3166 country code for the home country of the funding body.

For example, the country code 6252001 is for the United States.

State

The URI on the sws.geonames.org website for the ISO 3166 country subdivision code for the home subdivision (for example, state, province, or territory) of the funding body.

For example, the subdivision code 6093943 is for the Ontario province in Canada.

Downloading and Synchronizing the SciValFunders Vocabulary

Funding body information can be retrieved from the SciValFunders vocabulary directly using the API queries described below.

However, you can also download the entire vocabulary to handle queries locally.

To download the vocabulary and then synchronize your local copy with updates to it, you would use the following LDR APIs:

  • Get Entire Vocabulary: Retrieves the latest version of the entire vocabulary as an RDF file, stored inside a Zip file.
  • Get Last Update Date/Version for Vocabulary: Retrieves the timestamp and version number of the latest version of the vocabulary, allowing you to see if a newer version than the one that you last downloaded is now available.

Supported Queries

The following APIs allow you to query the vocabulary for funding body labels and other information:

RESTful Web Services Used by LDR APIs

All five RESTful web APIs use the HTTP method GET. GET is implied while querying using a web browser; however, it must be explicit while using a web service client.

Error Messages

If an error occurs during the execution of an API, the following standard HTTP error response codes are returned:

  • 500: A server-side error unrelated to the client query (for example, the server is unavailable or there are network issues).
  • 4xx: A client-side error; specifically for this API, one of the following:
    • 400: There is a syntax error in the query (for example, the query is missing a required parameter or includes an invalid argument).
    • 404: No content exists (for example, there is no match for the concept URI).
    • 405: The call is using an HTTP method that is not supported for this API.

Along with the error, a text message that briefly explains the nature of the problem is returned (for example, "Missing mandatory parameter: vocName").

If a valid query returns 0 results, an empty result set is returned.

For errors specific to each API, refer to the API's content page.

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