Graph Data
Linked Data andProperty Graphs
Contents
Example
LD/RDF
PG
SPARQL
Gremlin/Cypher
BIG dataApache Giraph / Bulk Synchronous Processing
Ideally?+arrays+URIs+attributes
Intro
SPARQLMain editor of query language spec (v1, v1.1)
RDFPractical wing of the semantic web
Helped with the syntax specs
Apache JenaImplements SPARQL 1.1
Biases ...
Graphs
A set of vertices (nodes) and edges (arcs)
Except the useful kind have labels on edges
and the nodes are just dots.
Graphs
G = ( V , E )
V Vertexes (Nodes)E Edges (Arcs, Links)
Graphs
Graphs For Information
Alice
Bob
Eve
listensToknows
Graphs For Information
Alice... has a name Alice Hacker... has an employee number
Linked Data / RDF
StandardsWhat it means
Syntaxes for exchanging data
Query language
URI name things globally
Uniform representationLink to another thing is same as link to a
value
Complex structures encoded in the basic mechanism
Schemaless data integration
Linked Data
make your stuff available on the Web (whatever format) 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
http://5stardata.info/
Linked Data / RDF
http://example/alice"Alice
Hacker"foaf:namehttp://example/bobfoaf:knowsprefix person: prefix
foaf:
foaf:name "Alice Hacker" ; foaf:knows .
foaf:name "Bob Tester" ; foaf:knows .
foaf:nameBob Testerfoaf:knows
JSON-LD
Links and semantics for the JSON ecosystem
{ "@context" : "http://example/person.jsonld", "@graph" : [ {
"@id" : "http://example/alice", "knows" : "http://example/bob",
"name" : "Alice Hacker" }, { "@id" : "http://example/bob", "knows"
: "http://example/alice", "name" : "Bob Tester" } ]}
SPARQL Query
prefix person: prefix foaf:
foaf:name "Alice Hacker" ; foaf:knows .
foaf:name "Bob Tester" ; foaf:knows .
PREFIX foaf:
SELECT ?name
WHERE
{ ?person foaf:name "Alice Hacker" ; ?person foaf:knows ?name . }
----------------| name |================| "Bob Tester"
|----------------
Property Graphs
Separates Links and Attributes
Nodes have attributes and so do edges
Different definitions https://github.com/tinkerpop/ is the de
facto standard
Not universal
Data exchange (web publishing) is not an objective
Analysis and schema-less data applications
Build
Graph graph = new TinkerGraph(); Vertex a =
graph.addVertex("alice"); Vertex b = graph.addVertex("bob");
a.setProperty("name","Alice Hacker"); b.setProperty("name","Bob
Coder"); Edge e1 = graph.addEdge("k1", a, b, "knows"); Edge e2 =
graph.addEdge("k2", b, a, "knows") ;
GSON
{ "edges" : [ { "_id" : "k1" , "_inV" : "bob" , "_label" :
"knows" , "_outV" : "alice" , "_type" : "edge" } , { "_id" : "k2" ,
"_inV" : "alice" , "_label" : "knows" , "_outV" : "bob" , "_type" :
"edge" } ] , "mode" : "NORMAL" , "vertices" : [ { "_id" : "bob" ,
"_type" : "vertex" , "name" : "Bob Coder" } , { "_id" : "alice" ,
"_type" : "vertex" , "name" : "Alice Hacker" } ]}
Gremlin
// Groovy to Java@SuppressWarnings("unchecked")Pipe pipe =
Gremlin.compile("g.v('alice').out('knows').name"); for(Object name
: pipe) { System.out.println((String) name);}
g.v('alice').out('knows').name
Cypher Query
Neo4J specific
Property Graph + labels (= types) node names
CREATE (alice { name: 'Alice Hacker'} ) , (bob { name: 'Bob
Tester'} ) , (alice) -[:knows]-> (bob) , (bob) -[:knows]->
(alice)
MATCH (a)-[:knows]->xWHERE a.name = 'Alice Hacker'RETURN
x.name
