Copyright 2007

LarKC Data Layer

Early adopter’s workshop

Objectives

To provide a standard API for RDF persistence To implement different strategies of data passing

(by value vs. by reference) To realize efficient RDF statement meta-data

association To offer utility model to simplify common RDF data

management tasks

ORDI Data Model

RDF model states universal-true Named graphs do not ensure the required

flexibility to model complex context/meta-data Provenance of the information Author / time stamp created / selection

Isolate data from the meta-data on RDF model level

ORDI Data Model Semantics

Neutral in terms of semantics Well defined data model operations

add – asserts new RDF statement remove – retract an RDF statement associate – add statement to a labelled group deassociate – remote statement from a labelled

group

ORDI Data Model Example

Operationsadd(a:alice, foaf:name, “Alice”, ng:g1)

add(b:bob, foaf:knows, a:alice, ng:g2, {l:l1})

add(a:alice, foaf:name, “Alice”, ng:g2)

associate(a:alice, foaf:name, “Alice”, ng:g1, l:l2)

associate(a:alice, foaf:name, “Alice”, ng:g2, l:l2)

associate(a:alice, foaf:name, “Alice”, ng:g2, l:l3)

remove(a:alice, foaf:name, “Alice”, ng:g2)

Alice

foaf:name

foaf:knows

foaf:name

b:bob

a:alice

ng:g1

ng:g2

L1

L2

L2

L3

Used Concepts in the Data Model

NG1 NG3

NG4 NG5

NG2

Labelled groupsof statements Labelled groups

of statements

Supported Sets of Statements

RDF data types Description Example

Set of statement RDF statements s1, p1, o1, ng1s2, p2, o2s3, p3, o3, ng3, {group1}

RDF graph Named graph s1, p1, o1, ng1, {group1}s2, p2, o2, ng1, {group2}s3, p3, o3, ng1

Dataset SPARQL dataset represents a collection of graphs

s1, p1, o1, ng1s2, p2, o2, ng2s3, p3, o3, ng3

Labelled group of statements

RDF group of statements

s1, p1, o1, ng1, {group1}s2, p2, o2, ng2, {group1}s3, p3, o3, ng3, {group1}

Java Interfaces to Implement the RDF Types

Java Interfaces to Create the RDF Types

The Different Implementations

Name Purpose Cost to pass 106 RDF statements

Set of statements Services to return RDF data (e.g., SPARQL construct and describe queries)

350MB memory

Named graph in memory Pass named graphs between plug-ins

350MB memory

HTTP published RDF graph Load chunks of RDF from URL

few KBs + time to load the data

Named graph retrieved from a SPARQL endpoint

Pass named graphs using a SPARQL endpoint

few KBs + time to transfer the data + to filter the dataset with SPARQL

SPARQL dataset Constrain RDF data exposed by a SPARQL endpoint with a list of graph names

few KBs + time to transfer the data + to filter the dataset with SPARQL

Labelled group of statements Pass arbitrary sets of RDF statements between plug-ins (e.g., graph priming)

few KBs + time to associate the statements + time to filter the labelled group

Questions?