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Commit 6aa1154

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Olaf Hartig
committed
adjusted the data source implementations to i) the introduction of the parser interface and ii) the changes of the request processor interface
1 parent 2b153bb commit 6aa1154

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9 files changed

+406
-318
lines changed

9 files changed

+406
-318
lines changed

‎src/org/linkeddatafragments/datasource/DataSource.java

Lines changed: 6 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,9 @@
11
package org.linkeddatafragments.datasource;
22

3-
import javax.servlet.http.HttpServletRequest;
4-
5-
import org.linkeddatafragments.config.ConfigReader;
3+
import org.linkeddatafragments.fragments.IFragmentRequestParser;
64
import org.linkeddatafragments.fragments.LinkedDataFragmentRequest;
5+
import org.linkeddatafragments.fragments.tpf.TPFRequestParser;
76
import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
8-
import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequestImpl;
97

108
/**
119
*
@@ -32,21 +30,16 @@ public String getTitle() {
3230
};
3331

3432
/**
35-
* This implementation assumes that the given request is a
36-
* {@link TriplePatternFragmentRequest}.
33+
* This implementation assumes that requests are
34+
* {@link TriplePatternFragmentRequest}s.
3735
*
3836
* Data sources for other types of {@link LinkedDataFragmentRequest}s must
3937
* override this method accordingly.
4038
*/
4139
@Override
42-
public IFragmentRequestProcessor getRequestProcessor(
43-
final HttpServletRequest request,
44-
final ConfigReader config )
40+
public IFragmentRequestParser getRequestParser()
4541
{
46-
final TriplePatternFragmentRequest r =
47-
new TriplePatternFragmentRequestImpl( request, config );
48-
49-
return getRequestProcessor( r );
42+
return new TPFRequestParser();
5043
}
5144

5245
@Override

‎src/org/linkeddatafragments/datasource/IDataSource.java

Lines changed: 5 additions & 13 deletions
Original file line numberDiff line numberDiff line change
@@ -2,10 +2,7 @@
22

33
import java.io.Closeable;
44

5-
import javax.servlet.http.HttpServletRequest;
6-
7-
import org.linkeddatafragments.config.ConfigReader;
8-
import org.linkeddatafragments.fragments.LinkedDataFragmentRequest;
5+
import org.linkeddatafragments.fragments.IFragmentRequestParser;
96

107
/**
118
* A data source of Linked Data Fragments.
@@ -20,17 +17,12 @@ public interface IDataSource extends Closeable {
2017
public String getDescription();
2118

2219
/**
23-
* Returns a data source specific processor for the given request of a
24-
* Linked Data Fragment.
20+
* Returns a data source specific {@link IFragmentRequestParser}.
2521
*/
26-
IFragmentRequestProcessor getRequestProcessor(
27-
final HttpServletRequest request,
28-
final ConfigReader config );
22+
IFragmentRequestParser getRequestParser();
2923

3024
/**
31-
* Returns a data source specific processor for the given request of a
32-
* Linked Data Fragment.
25+
* Returns a data source specific {@link IFragmentRequestProcessor}.
3326
*/
34-
IFragmentRequestProcessor getRequestProcessor(
35-
final LinkedDataFragmentRequest request );
27+
IFragmentRequestProcessor getRequestProcessor();
3628
}

‎src/org/linkeddatafragments/datasource/hdt/HdtBasedRequestProcessorForTPFs.java

Lines changed: 138 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,138 @@
1+
package org.linkeddatafragments.datasource.hdt;
2+
3+
import java.io.IOException;
4+
5+
import org.linkeddatafragments.datasource.AbstractJenaBasedRequestProcessorForTriplePatterns;
6+
import org.linkeddatafragments.datasource.IFragmentRequestProcessor;
7+
import org.linkeddatafragments.fragments.LinkedDataFragment;
8+
import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
9+
import org.rdfhdt.hdt.enums.TripleComponentRole;
10+
import org.rdfhdt.hdt.hdt.HDT;
11+
import org.rdfhdt.hdt.hdt.HDTManager;
12+
import org.rdfhdt.hdt.triples.IteratorTripleID;
13+
import org.rdfhdt.hdt.triples.TripleID;
14+
import org.rdfhdt.hdtjena.NodeDictionary;
15+
16+
import com.hp.hpl.jena.graph.Triple;
17+
import com.hp.hpl.jena.rdf.model.Model;
18+
import com.hp.hpl.jena.rdf.model.ModelFactory;
19+
import com.hp.hpl.jena.rdf.model.Property;
20+
import com.hp.hpl.jena.rdf.model.RDFNode;
21+
import com.hp.hpl.jena.rdf.model.Resource;
22+
23+
/**
24+
* Implementation of {@link IFragmentRequestProcessor} that processes
25+
* {@link TriplePatternFragmentRequest}s over data stored in HDT.
26+
*
27+
* @author Ruben Verborgh
28+
* @author <a href="http://olafhartig.de">Olaf Hartig</a>
29+
*/
30+
public class HdtBasedRequestProcessorForTPFs
31+
extends AbstractJenaBasedRequestProcessorForTriplePatterns
32+
{
33+
protected final HDT datasource;
34+
protected final NodeDictionary dictionary;
35+
36+
/**
37+
* Creates the request processor.
38+
*
39+
* @param hdtFile the HDT datafile
40+
* @throws IOException if the file cannot be loaded
41+
*/
42+
public HdtBasedRequestProcessorForTPFs( String hdtFile ) throws IOException
43+
{
44+
datasource = HDTManager.mapIndexedHDT( hdtFile, null ); // listener=null
45+
dictionary = new NodeDictionary( datasource.getDictionary() );
46+
}
47+
48+
@Override
49+
protected Worker getWorker( final TriplePatternFragmentRequest request )
50+
throws IllegalArgumentException
51+
{
52+
return new Worker( request );
53+
}
54+
55+
56+
protected class Worker
57+
extends AbstractJenaBasedRequestProcessorForTriplePatterns.Worker
58+
{
59+
public Worker( final TriplePatternFragmentRequest request ) {
60+
super( request );
61+
}
62+
63+
@Override
64+
protected LinkedDataFragment createFragment( final Resource subject,
65+
final Property predicate,
66+
final RDFNode object,
67+
final long offset,
68+
final long limit )
69+
{
70+
// look up the result from the HDT datasource)
71+
int subjectId = subject == null ? 0 : dictionary.getIntID(subject.asNode(), TripleComponentRole.SUBJECT);
72+
int predicateId = predicate == null ? 0 : dictionary.getIntID(predicate.asNode(), TripleComponentRole.PREDICATE);
73+
int objectId = object == null ? 0 : dictionary.getIntID(object.asNode(), TripleComponentRole.OBJECT);
74+
75+
if (subjectId < 0 || predicateId < 0 || objectId < 0) {
76+
return createEmptyTriplePatternFragment();
77+
}
78+
79+
final Model triples = ModelFactory.createDefaultModel();
80+
IteratorTripleID matches = datasource.getTriples().search(new TripleID(subjectId, predicateId, objectId));
81+
boolean hasMatches = matches.hasNext();
82+
83+
if (hasMatches) {
84+
// try to jump directly to the offset
85+
boolean atOffset;
86+
if (matches.canGoTo()) {
87+
try {
88+
matches.goTo(offset);
89+
atOffset = true;
90+
} // if the offset is outside the bounds, this page has no matches
91+
catch (IndexOutOfBoundsException exception) {
92+
atOffset = false;
93+
}
94+
} // if not possible, advance to the offset iteratively
95+
else {
96+
matches.goToStart();
97+
for (int i = 0; !(atOffset = i == offset) && matches.hasNext(); i++) {
98+
matches.next();
99+
}
100+
}
101+
// try to add `limit` triples to the result model
102+
if (atOffset) {
103+
for (int i = 0; i < limit && matches.hasNext(); i++) {
104+
triples.add(triples.asStatement(toTriple(matches.next())));
105+
}
106+
}
107+
}
108+
109+
// estimates can be wrong; ensure 0 is returned if there are no results,
110+
// and always more than actual results
111+
final long estimatedTotal = triples.size() > 0 ?
112+
Math.max(offset + triples.size() + 1, matches.estimatedNumResults())
113+
: hasMatches ?
114+
Math.max(matches.estimatedNumResults(), 1)
115+
: 0;
116+
117+
// create the fragment
118+
final boolean isLastPage = ( estimatedTotal < offset + limit );
119+
return createTriplePatternFragment( triples, estimatedTotal, isLastPage );
120+
}
121+
122+
} // end of Worker
123+
124+
/**
125+
* Converts the HDT triple to a Jena Triple.
126+
*
127+
* @param tripleId the HDT triple
128+
* @return the Jena triple
129+
*/
130+
private Triple toTriple(TripleID tripleId) {
131+
return new Triple(
132+
dictionary.getNode(tripleId.getSubject(), TripleComponentRole.SUBJECT),
133+
dictionary.getNode(tripleId.getPredicate(), TripleComponentRole.PREDICATE),
134+
dictionary.getNode(tripleId.getObject(), TripleComponentRole.OBJECT)
135+
);
136+
}
137+
138+
}

‎src/org/linkeddatafragments/datasource/hdt/HdtDataSource.java

Lines changed: 4 additions & 107 deletions
Original file line numberDiff line numberDiff line change
@@ -2,25 +2,8 @@
22

33
import java.io.IOException;
44

5-
import org.linkeddatafragments.datasource.AbstractRequestProcessorForTriplePatterns;
65
import org.linkeddatafragments.datasource.DataSource;
76
import org.linkeddatafragments.datasource.IFragmentRequestProcessor;
8-
import org.linkeddatafragments.fragments.LinkedDataFragment;
9-
import org.linkeddatafragments.fragments.LinkedDataFragmentRequest;
10-
import org.linkeddatafragments.fragments.tpf.TriplePatternFragmentRequest;
11-
import org.rdfhdt.hdt.enums.TripleComponentRole;
12-
import org.rdfhdt.hdt.hdt.HDT;
13-
import org.rdfhdt.hdt.hdt.HDTManager;
14-
import org.rdfhdt.hdt.triples.IteratorTripleID;
15-
import org.rdfhdt.hdt.triples.TripleID;
16-
import org.rdfhdt.hdtjena.NodeDictionary;
17-
18-
import com.hp.hpl.jena.graph.Triple;
19-
import com.hp.hpl.jena.rdf.model.Model;
20-
import com.hp.hpl.jena.rdf.model.ModelFactory;
21-
import com.hp.hpl.jena.rdf.model.Property;
22-
import com.hp.hpl.jena.rdf.model.RDFNode;
23-
import com.hp.hpl.jena.rdf.model.Resource;
247

258
/**
269
* An HDT data source of Basic Linked Data Fragments.
@@ -30,8 +13,7 @@
3013
*/
3114
public class HdtDataSource extends DataSource {
3215

33-
private final HDT datasource;
34-
private final NodeDictionary dictionary;
16+
protected final HdtBasedRequestProcessorForTPFs requestProcessor;
3517

3618
/**
3719
* Creates a new HdtDataSource.
@@ -43,98 +25,13 @@ public class HdtDataSource extends DataSource {
4325
*/
4426
public HdtDataSource(String title, String description, String hdtFile) throws IOException {
4527
super(title, description);
46-
datasource = HDTManager.mapIndexedHDT(hdtFile, null);
47-
dictionary = new NodeDictionary(datasource.getDictionary());
28+
requestProcessor = new HdtBasedRequestProcessorForTPFs( hdtFile );
4829
}
4930

5031
@Override
51-
public IFragmentRequestProcessor getRequestProcessor(
52-
final LinkedDataFragmentRequest request )
32+
public IFragmentRequestProcessor getRequestProcessor()
5333
{
54-
if ( ! (request instanceof TriplePatternFragmentRequest) )
55-
throw new IllegalArgumentException();
56-
57-
return new MyProcessor( (TriplePatternFragmentRequest) request );
58-
}
59-
60-
protected class MyProcessor extends AbstractRequestProcessorForTriplePatterns
61-
{
62-
public MyProcessor( final TriplePatternFragmentRequest request ) {
63-
super( request );
34+
return requestProcessor;
6435
}
6536

66-
@Override
67-
protected LinkedDataFragment createFragment( final Resource subject,
68-
final Property predicate,
69-
final RDFNode object,
70-
final long offset,
71-
final long limit )
72-
{
73-
// look up the result from the HDT datasource)
74-
int subjectId = subject == null ? 0 : dictionary.getIntID(subject.asNode(), TripleComponentRole.SUBJECT);
75-
int predicateId = predicate == null ? 0 : dictionary.getIntID(predicate.asNode(), TripleComponentRole.PREDICATE);
76-
int objectId = object == null ? 0 : dictionary.getIntID(object.asNode(), TripleComponentRole.OBJECT);
77-
78-
if (subjectId < 0 || predicateId < 0 || objectId < 0) {
79-
return createEmptyTriplePatternFragment();
80-
}
81-
82-
final Model triples = ModelFactory.createDefaultModel();
83-
IteratorTripleID matches = datasource.getTriples().search(new TripleID(subjectId, predicateId, objectId));
84-
boolean hasMatches = matches.hasNext();
85-
86-
if (hasMatches) {
87-
// try to jump directly to the offset
88-
boolean atOffset;
89-
if (matches.canGoTo()) {
90-
try {
91-
matches.goTo(offset);
92-
atOffset = true;
93-
} // if the offset is outside the bounds, this page has no matches
94-
catch (IndexOutOfBoundsException exception) {
95-
atOffset = false;
96-
}
97-
} // if not possible, advance to the offset iteratively
98-
else {
99-
matches.goToStart();
100-
for (int i = 0; !(atOffset = i == offset) && matches.hasNext(); i++) {
101-
matches.next();
102-
}
103-
}
104-
// try to add `limit` triples to the result model
105-
if (atOffset) {
106-
for (int i = 0; i < limit && matches.hasNext(); i++) {
107-
triples.add(triples.asStatement(toTriple(matches.next())));
108-
}
109-
}
110-
}
111-
112-
// estimates can be wrong; ensure 0 is returned if there are no results,
113-
// and always more than actual results
114-
final long estimatedTotal = triples.size() > 0
115-
? Math.max(offset + triples.size() + 1, matches.estimatedNumResults())
116-
: hasMatches
117-
? Math.max(matches.estimatedNumResults(), 1)
118-
: 0;
119-
120-
// create the fragment
121-
final boolean isLastPage = ( estimatedTotal < offset + limit );
122-
return createTriplePatternFragment( triples, estimatedTotal, isLastPage );
123-
}
124-
125-
} // end of MyProcessor
126-
127-
/**
128-
* Converts the HDT triple to a Jena Triple.
129-
*
130-
* @param tripleId the HDT triple
131-
* @return the Jena triple
132-
*/
133-
private Triple toTriple(TripleID tripleId) {
134-
return new Triple(
135-
dictionary.getNode(tripleId.getSubject(), TripleComponentRole.SUBJECT),
136-
dictionary.getNode(tripleId.getPredicate(), TripleComponentRole.PREDICATE),
137-
dictionary.getNode(tripleId.getObject(), TripleComponentRole.OBJECT)
138-
);
139-
}
14037
}

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