This document describes LDCache, a cache for Linked Data-driven web applications. LDCache solves problems with relying on third party data sources like availability and alignment issues. It pre-fetches and caches RDF data based on a configuration to follow certain predicates and resources to a specified depth. Developers can then query the cache to retrieve consistent RDF data in various formats.

1. LDCache
A cache for Linked Data-driven Web applications
Developers Workshop at ISWC 2014
2014-10-19
Hannes Ebner, PhD
hannes@metasolutions.se
metasolutions.se

2. Overview
● Background
● Problem
● Solution
● Usage

3. Background (1/3)

4. Background (2/3)

5. Background (3/3)

6. Problem
Nobel Laureate
DBpedia
Freebase
YAGO
Nobel Prize
VIAF
...
Bio2RDF
Linked Life Data
...

7. Solution (1/2)

8. Solution (2/2)
● A Linked Data Cache: LDCache
● LDCache solves several problems
○ Reliability issues of third party data sources
○ Streamlining multiple dereferenciation steps
○ RDF format alignment
○ Offloading to a CDN

9. Usage (1/2)
● Java
○ Web container or standalone
● Simple JSON-based configuration
○ Root-resource(s) to start from
○ Predicates to follow
○ The maximum depth for graph traversal
○ Whitelist of destination prefixes
○ Whitelist of literal languages
○ ...
● Only pre-fetched resources are returned
● LDCache is not a caching proxy

10. Usage (2/2)
GET http://{ldc-base}/?
url=http://data.nobelprize.org/resource/laureate/6&
follow=dbp:doctoralStudent,owl:sameAs,dbp:spouse&
followDepth=3&
includeDestinations=http://dbpedia.org/&
format=application/ld+json

11. LDCache
License Apache License 2.0
Documentation http://entrystore.org/ldcache/
Source code https://bitbucket.org/metasolutions/ldcache/
Slides http://ebner.se/20141019
Paper http://ceur-ws.org/Vol-1268/paper12.pdf
Contact hannes@metasolutions.se