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Initial Usage Analysis

of DBpedia's

Triple Pattern Fragments
Ruben Verborgh,

Erik Mannens & Rik Van de Walle
What role will the Semantic Web play

for the future generation?
Will it be remotely as important

as the Web now is to us?
There used to be no applications

because there was no data.
Linked Data more of less solved

this chicken-and-egg problem.
There are no applications

because data is not queryable.
SPARQL endpoints are unreliable.

Data dumps are not live.
We analyzed DBpedia’s low-cost

Triple Pattern Fragments interface

between Nov 2014 and Feb 2015.
Over 4M requests were made.

There was 1 minute of downtime.
Web interfaces to triples
Four months of fragments
Extending the analysis
Web interfaces to triples
Four months of fragments
Extending the analysis
Web interfaces act as gateways

between clients and databases.
Database Client
Web
interface
The interface hides the database schema.
The interface restricts the kind of queries.
No sane Web developer or admin

would give direct database access.
Database Client
Web
interface
The client must know the database schema.
The client can ask any query.
SPARQL endpoints happily give

direct access to the database.
Triple

store
Client
SPARQL
protocol
The client must know the database schema.
The client can ask any query.
SPARQL interfaces are expensive,

so we have an availability problem.
There are few SPARQL endpoints

because hosting them is expensive.
Many of the endpoints that exist

suffer from low availability.
You already give data for free.

Do you have to pay for query time as well?
Data dumps allow you to set up

your own private SPARQL endpoint.
But then we no longer query the Web…
No usage statistics whatsoever.
Not everybody can do this:

mobile devices, non-technical users, …
The interface hides the database schema.
The interface restricts the kind of queries.
A Triple Pattern Fragments interface

acts as a gateway to an RDF source.
RDF

source
Client
TPF

interface
A Triple Pattern Fragments interface

acts as a gateway to an RDF source.
Client can only ask ?s ?p ?o patterns.
Decompose complex SPARQL queries

on the client client-side.
Low server cost, highly cacheable,

but higher bandwidth and query time.
Web interfaces to triples
Four months of fragments
Extending the analysis
In mid-October 2014, we started

an official TPF interface for DBpedia.
Will this interface be used?
How will clients use it?
Will the availability be sufficient

for live application usage?
The server is deployed virtually,
availability monitored externally.
Amazon Elastic Compute Cloud

c3.2xlarge machine (8 CPU, 15GB RAM)
Compressed HDT format as backend
Pingdom for analysis
4.5 million Triple Pattern Fragments

of DBpedia 2014@en were requested.
The TPF client library consumed most,

followed by crawlers and Chrome.
Turtle as content type is most popular,

but being surpassed by TriG.
Most requests come from Europe,

the US and China are following.
The “type” fragment was popular,

but it’s hard to conclude anything.
A quarter of all requests was cached

(but we could cache everything).
During four months,

the API had 99.9994% availability.
We deeply apologize for

that one minute of downtime

in November.
Web interfaces to triples
Four months of fragments
Extending the analysis
We don’t know exactly

which clients executed queries.
Was the TPF client used standalone?
As a library of another application?
Also hard for SPARQL endpoints.
The analysis did not give insights

in which queries clients executed.
Good for privacy!
We can try reconstructing SPARQL queries,

but maybe clients did something else.
We only know with SPARQL endpoints,

not with data dumps or LD documents.
We could learn from the human Web:

can clients give explicit feedback?
“This is the query I executed.

It took me 5 seconds.”
Potential source of insights,

but clients need a gain.
Will this be representative/truthful?
Web interfaces to triples
Four months of fragments
Extending the analysis
We have a >99.999% available API

to the most popular RDF datasource.
No more excuses not to build apps.
So where are they?
Is something else holding us back?
We need to think differently

on how to build Linked Data apps.
The paradigm of querying a database

and waiting for the results

does not scale to the Web.
Live data requires new interfaces

and new visualizations.
We need developers to build bridges

from data to end users.
Now that the chicken-and-egg problem

and the availability problems are solved,

we need to tackle fundamental questions.
Where are the killer apps

the next generation is waiting for?
Initial Usage Analysis

of DBpedia's

Triple Pattern Fragments
@RubenVerborgh

ruben.verborgh.org

linkeddatafragments.org

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Initial Usage Analysis of DBpedia's Triple Pattern Fragments

  • 1. Initial Usage Analysis
 of DBpedia's
 Triple Pattern Fragments Ruben Verborgh,
 Erik Mannens & Rik Van de Walle
  • 2.
  • 3. What role will the Semantic Web play
 for the future generation? Will it be remotely as important
 as the Web now is to us?
  • 4. There used to be no applications
 because there was no data. Linked Data more of less solved
 this chicken-and-egg problem.
  • 5. There are no applications
 because data is not queryable. SPARQL endpoints are unreliable.
 Data dumps are not live.
  • 6. We analyzed DBpedia’s low-cost
 Triple Pattern Fragments interface
 between Nov 2014 and Feb 2015. Over 4M requests were made.
 There was 1 minute of downtime.
  • 7. Web interfaces to triples Four months of fragments Extending the analysis
  • 8. Web interfaces to triples Four months of fragments Extending the analysis
  • 9. Web interfaces act as gateways
 between clients and databases. Database Client Web interface The interface hides the database schema. The interface restricts the kind of queries.
  • 10. No sane Web developer or admin
 would give direct database access. Database Client Web interface The client must know the database schema. The client can ask any query.
  • 11. SPARQL endpoints happily give
 direct access to the database. Triple
 store Client SPARQL protocol The client must know the database schema. The client can ask any query.
  • 12. SPARQL interfaces are expensive,
 so we have an availability problem. There are few SPARQL endpoints
 because hosting them is expensive. Many of the endpoints that exist
 suffer from low availability. You already give data for free.
 Do you have to pay for query time as well?
  • 13. Data dumps allow you to set up
 your own private SPARQL endpoint. But then we no longer query the Web… No usage statistics whatsoever. Not everybody can do this:
 mobile devices, non-technical users, …
  • 14. The interface hides the database schema. The interface restricts the kind of queries. A Triple Pattern Fragments interface
 acts as a gateway to an RDF source. RDF
 source Client TPF
 interface
  • 15. A Triple Pattern Fragments interface
 acts as a gateway to an RDF source. Client can only ask ?s ?p ?o patterns. Decompose complex SPARQL queries
 on the client client-side. Low server cost, highly cacheable,
 but higher bandwidth and query time.
  • 16.
  • 17.
  • 18. Web interfaces to triples Four months of fragments Extending the analysis
  • 19. In mid-October 2014, we started
 an official TPF interface for DBpedia. Will this interface be used? How will clients use it? Will the availability be sufficient
 for live application usage?
  • 20. The server is deployed virtually, availability monitored externally. Amazon Elastic Compute Cloud
 c3.2xlarge machine (8 CPU, 15GB RAM) Compressed HDT format as backend Pingdom for analysis
  • 21. 4.5 million Triple Pattern Fragments
 of DBpedia 2014@en were requested.
  • 22. The TPF client library consumed most,
 followed by crawlers and Chrome.
  • 23. Turtle as content type is most popular,
 but being surpassed by TriG.
  • 24. Most requests come from Europe,
 the US and China are following.
  • 25. The “type” fragment was popular,
 but it’s hard to conclude anything.
  • 26. A quarter of all requests was cached
 (but we could cache everything).
  • 27. During four months,
 the API had 99.9994% availability. We deeply apologize for
 that one minute of downtime
 in November.
  • 28. Web interfaces to triples Four months of fragments Extending the analysis
  • 29. We don’t know exactly
 which clients executed queries. Was the TPF client used standalone? As a library of another application? Also hard for SPARQL endpoints.
  • 30. The analysis did not give insights
 in which queries clients executed. Good for privacy! We can try reconstructing SPARQL queries,
 but maybe clients did something else. We only know with SPARQL endpoints,
 not with data dumps or LD documents.
  • 31. We could learn from the human Web:
 can clients give explicit feedback? “This is the query I executed.
 It took me 5 seconds.” Potential source of insights,
 but clients need a gain. Will this be representative/truthful?
  • 32. Web interfaces to triples Four months of fragments Extending the analysis
  • 33. We have a >99.999% available API
 to the most popular RDF datasource. No more excuses not to build apps. So where are they? Is something else holding us back?
  • 34. We need to think differently
 on how to build Linked Data apps. The paradigm of querying a database
 and waiting for the results
 does not scale to the Web. Live data requires new interfaces
 and new visualizations.
  • 35. We need developers to build bridges
 from data to end users. Now that the chicken-and-egg problem
 and the availability problems are solved,
 we need to tackle fundamental questions. Where are the killer apps
 the next generation is waiting for?
  • 36. Initial Usage Analysis
 of DBpedia's
 Triple Pattern Fragments @RubenVerborgh
 ruben.verborgh.org
 linkeddatafragments.org