001/** 002 * Copyright (C) 2007 - 2016, Jens Lehmann 003 * 004 * This file is part of DL-Learner. 005 * 006 * DL-Learner is free software; you can redistribute it and/or modify 007 * it under the terms of the GNU General Public License as published by 008 * the Free Software Foundation; either version 3 of the License, or 009 * (at your option) any later version. 010 * 011 * DL-Learner is distributed in the hope that it will be useful, 012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 014 * GNU General Public License for more details. 015 * 016 * You should have received a copy of the GNU General Public License 017 * along with this program. If not, see <http://www.gnu.org/licenses/>. 018 */ 019package org.dllearner.algorithms.pattern; 020 021import org.aksw.jena_sparql_api.core.QueryExecutionFactory; 022import org.aksw.jena_sparql_api.pagination.core.PaginationUtils; 023import org.apache.jena.query.ParameterizedSparqlString; 024import org.apache.jena.query.Query; 025import org.apache.jena.rdf.model.Model; 026import org.apache.jena.rdf.model.ModelFactory; 027import org.dllearner.kb.SparqlEndpointKS; 028import org.semanticweb.owlapi.model.OWLClass; 029 030import java.util.concurrent.TimeUnit; 031 032/** 033 * @author Lorenz Buehmann 034 * 035 */ 036public class TimeBasedFragmentExtractor implements FragmentExtractor{ 037 038 public static final FragmentExtractionStrategy extractionStrategy = FragmentExtractionStrategy.TIME; 039 private SparqlEndpointKS ks; 040 private QueryExecutionFactory qef; 041 042 private long maxExecutionTimeInMilliseconds; 043 private long startTime; 044 045 public TimeBasedFragmentExtractor(SparqlEndpointKS ks, int maxExecutionTimeInMilliseconds, TimeUnit timeUnit) { 046 this.ks = ks; 047 this.maxExecutionTimeInMilliseconds = timeUnit.toMillis(maxExecutionTimeInMilliseconds); 048 049 qef = ks.getQueryExecutionFactory(); 050 } 051 052 /* (non-Javadoc) 053 * @see org.dllearner.algorithms.pattern.FragmentExtractor#extractFragment(org.dllearner.core.owl.NamedClass) 054 */ 055 @Override 056 public Model extractFragment(OWLClass cls, int maxFragmentDepth) { 057 startTime = System.currentTimeMillis(); 058 Model fragment = ModelFactory.createDefaultModel(); 059 060 Query query = buildConstructQuery(cls, maxFragmentDepth); 061 062 long pageSize = PaginationUtils.adjustPageSize(qef, 10000); 063 query.setLimit(pageSize); 064 int offset = 0; 065 while(getRemainingRuntime() > 0){ 066 query.setOffset(offset);System.out.println(query); 067 Model model = qef.createQueryExecution(query).execConstruct(); 068 fragment.add(model); 069 offset += pageSize; 070 } 071 return fragment; 072 } 073 074 private Query buildConstructQuery(OWLClass cls, int depth){ 075 StringBuilder sb = new StringBuilder(); 076 int maxVarCnt = 0; 077 sb.append("CONSTRUCT {\n"); 078 sb.append("?s").append("?p0 ").append("?o0").append(".\n"); 079 for(int i = 1; i < depth-1; i++){ 080 sb.append("?o").append(i-1).append(" ").append("?p").append(i).append(" ").append("?o").append(i).append(".\n"); 081 maxVarCnt++; 082 } 083 sb.append("?o").append(maxVarCnt).append(" a ?type.\n"); 084 sb.append("}\n"); 085 sb.append("WHERE {\n"); 086 sb.append("?s a ?cls."); 087 sb.append("?s").append("?p0 ").append("?o0").append(".\n"); 088 for(int i = 1; i < depth-1; i++){ 089 sb.append("OPTIONAL{\n"); 090 sb.append("?o").append(i-1).append(" ").append("?p").append(i).append(" ").append("?o").append(i).append(".\n"); 091 } 092 sb.append("OPTIONAL{?o").append(maxVarCnt).append(" a ?type}.\n"); 093 for(int i = 1; i < depth-1; i++){ 094 sb.append("}"); 095 } 096 097 sb.append("}\n"); 098 ParameterizedSparqlString template = new ParameterizedSparqlString(sb.toString()); 099 template.setIri("cls", cls.toStringID()); 100 return template.asQuery(); 101 } 102 103 private long getRemainingRuntime(){ 104 return maxExecutionTimeInMilliseconds - (System.currentTimeMillis() - startTime); 105 } 106 107}