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What is Linked Data?

May 28, 2020


Library and Information Science Questions Answers Quizzes (LIS Quiz)



QUESTION

Choose ALL that apply

What is Linked Data?
OPTIONS

(a) a set of techniques for expressing, exposing, and publishing data

(b) a set of best practices for publishing and connecting structured data on the Web

(c) using Web technologies to connect data that is related but stored in different locations


ANSWER

(a) (b) and (c) all




Linked Data is (a) a set of techniques for expressing, exposing, and publishing data, (b) a set of best practices for publishing and connecting structured data on the Web, and (c) using Web technologies to connect data that is related but stored in different locations.






Linked Data is a set of techniques for the publication of data on the Web using standard formats and interfaces. Data that conforms to those techniques is also called Linked Data.




Linked Data

  • One practical application of these technologies to real-world data
  • A style of publishing and interlinking structured data on the Web so that it can be interlinked and become more useful
  • Builds upon existing well established Web technologies such as HTTP, RDF and URIs
    • Applying the Linked Data principles to legacy data sources integrates data

The term Linked Data was coined by Sir Tim Berners-Lee in his Linked Data Web architecture note 

The Wikipedia definition of Linked Data is, "Linked Data is a term used to describe a method of exposing, sharing, and connecting data on the Semantic Web. The practice emphasizes Web access to data using existing Web technologies such as URIs and HTTP.“

Linked Data builds upon existing well established HTTP technology. Valuable and good quality data exist in legacy database systems can be exploit to realize a Web of Data.


Linked Data makes the Web a HUGE database

  • Data is more useful if it links to related data, documents, and descriptions
  • Data becomes Linked Data when it links to related resources

There is a huge volume of data exists on the Web. However, many times the data is buried in in database silos in organizations. 

Linked data is about making data available in standard ways so that others can use and link to. This is essential to connect the data we have into a web. It is the unexpected reuse of information which is the value added by the web.


Basics of Linked Data

  • Use URIs as names for things 
  • Use HTTP URIs so that people can look up those names
  • When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL) 
  • Include links to other URIs, so that they can discover more things

Berners-Lee outlined these four rules of Linked Data in his design issues notes.

These rules are broad guiding principles on how to publish and interlink data in a human and machine readable way by using Semantic Web technologies.



Linked Data 5-star scheme

  • Make your stuff available on the Web (*)
  • Make it available as structured data (**)
  • Use non-proprietary formats (***)
  • Use URIs to identify things, so that people can point at your stuff (****)
  • Link your data to other data to provide context (*****)

 In 2010 Tim Berners-Lee introduced a 5 star rating to his Linked Data design issues page to encourage data publishers along the road to good Linked Data.

The goal is to encourage data owners to publish their data according to Linked Data principles by asking: Is our linked open data 5 star?

The first star is assigned for the big first step of making the data available on the Web (in whatever format).

All following stars are intended to make the data easier to discover, use, and understand.

The second star is assigned for making the data available in a machine readable, structured way (this can even be an Excel spreadsheet).

The third star is for using non-proprietary formats (e.g., the Open Document Format; ODS instead of XLS).

The fourth star is for using open W3C standards such as RDF to identify resources.

The fifth star is for linking your own data to other datasets.

Again, the motivation here is to have a simple stack of consecutive steps that reward improved access to data by additional stars.

Five Stars of Linked Data Vocabulary Use [http://geog.ucsb.edu/~jano/swj653.pdf]


Linked Data

  • Machine-actionable data
    • Describing ➨ identifying
      • “Record” ➨ Graph
    • Mapping ➨ linking
    • String to things
“From Strings to Things” Michael Panzer 
http://rbms.info/conferences2/preconfdocs/2012/plenary_2_panzer.pdfF


Relationship between Linked Data and the Semantic Web
  • Semantic Web is a vision of a “Web of Data”
  • Linked Data is a means to achieve that vision
  • Semantic Web is What and Linked Data is How


Current state of Linked Data in libraries

  • Developing use cases
  • Structuring, cleaning and releasing data
  • Developing new frameworks and tools
  • Exploration, prototypes and proofs of concept
  • Learning!









SEE ALSO


REFERENCES

1. Library of Congress, "Semantic Web and Linked Data Quiz," https://www.loc.gov/catworkshop/bibframe/Training/part1a/index.htm (accessed February 11, 2020).

2. Library of Congress, "The Semantic Web and Linked Data Concepts: A Basic Overview," https://www.loc.gov/catworkshop/bibframe/Module1-Part1.pptx (accessed February 11, 2020).

3. Tim Berners-Lee, James Hendler and Ora Lassila, "The Semantic Web", Scientific American, May 2001, p. 29-37.

4. W3C. What is the Semantic Web? Downloaded February 12, 2014 from http://www.w3.org/2001/sw/

5. Wikipedia, "Semantic Web," https://en.wikipedia.org/wiki/Semantic_Web (accessed May 19, 2020)


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