Tech TalkBIBFRAME Working Group

18 August 2015

Allison Jai O’Dell, Metadata Librarian | AJODELL@ufl.edu | (352) 273-2667 | 404 Library East

Linked DataBecause once upon a time folks realized that finding stuff on the interwebs was

difficult without authority control.

Linked Data Principles

• 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.

http://www.w3.org/DesignIssues/LinkedData.html

Use URIs as names for things

• Uniform Resource Identifiers (URIs) are codes that uniquely identify

(that is, name and help locate) resources

• URIs can be of two types:

• Uniform Resource Names (URNs), which uniquely name a resource

• Uniform Resource Locators (URLs), which help locate a resource

• URIs may serve either or both of these functions

• The duality of naming and locating via URIs is important to how

Linked Data works

(and yes, fellow librarians, it’s basically authority control)

Use HTTP URIs so that people can look up those names

• The Hypertext Transfer Protocol (HTTP) is the standard by which

data is communicated on the World Wide Web

• Using HTTP URIs makes an identifier scheme accessible and

communicable on the Web

• An HTTP URI such as: http://www.example.org/vocab#Allison_ODell

can be used as a unique character string to identify Allison O’Dell, and

also, as a Web address for locating information about Allison O’Dell

When someone looks up a URI, provide useful information, using the standards (RDF, SPARQL)

• Because HTTP URIs are on the Web, they take advantage of Web technologies. One can:• Point a browser at an HTTP URI and read the information that is there.

• Run a query against the data, and obtain the information that is there

• An HTTP URI serves three functions: • to uniquely name things

• to help locate things

• to gain information about things

This is where it gets cool.authority control + taxonomy + encyclopedic information + access = awesome

Include links to other URIs, so that they can discover more things

5-star Linked Data

★ make your stuff available on the Web under an open license

★★ make it available as structured data

(e.g., Excel instead of image scan of a table)

★★★ use non-proprietary formats

(e.g., CSV instead of Excel)

★★★★ use URIs to denote things, so that people can point at

your stuff

★★★★★ link your data to other data to provide context

Resource Description Framework (RDF)

• The standard model for creating Linked Data

• Expresses data simply, by naming two things and the relationship

between them – a structure known as a “triple,” because it is a three-

part statement.

“Allison O’Dell” “lives in” “Gainesville, Florida”

• Each part of the triple can be identified by a URI

< http://www.example.org/vocab#Allison_ODell >

< http://www.example.org/vocab#lives_in >

< http://www.example.org/vocab#Gainesville >

Triples = Easy to Link

This is where it gets really cool.triples + graph databases + SPARQL = data merger and inferencing power

Relational Databases (awesome for straightforward stuff)

• Relationships between tables

• Advantages:

• Easier data updates

• Faster processes

• Less storage space

• Disadvantages:

• Tables = rigid structure

• Tables = annoying to query

Graph Databases (awesome for complex stuff)

• Relationships between everything

• Advantages:

• Graph = easy to query

• Allows variation in data and relationships

• Extensible: scales easier

• Inferencing power

• Disadvantages:

• Slow processing

• More storage space

SPARQL

• Query language for RDF data

• More intuitive than SQL:

• Queries based on relationships, rather than on the structure of tables

• Queries can use the underlying taxonomy or data model

online [card] catalogLinked Data puts the card catalog model on the Web