Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.jena.rdfconnection; import static java.util.Objects.requireNonNull; import java.io.File; import java.io.InputStream; import java.util.Objects; import java.util.function.Supplier; import org.apache.http.HttpEntity; import org.apache.http.client.HttpClient; import org.apache.http.entity.EntityTemplate; import org.apache.http.protocol.HttpContext; import org.apache.jena.atlas.io.IO; import org.apache.jena.atlas.lib.InternalErrorException; import org.apache.jena.atlas.web.HttpException; import org.apache.jena.atlas.web.TypedInputStream; import org.apache.jena.graph.Graph; import org.apache.jena.query.*; import org.apache.jena.rdf.model.Model; import org.apache.jena.rdf.model.ModelFactory; import org.apache.jena.riot.*; import org.apache.jena.riot.web.HttpCaptureResponse; import org.apache.jena.riot.web.HttpOp; import org.apache.jena.riot.web.HttpResponseLib; import org.apache.jena.sparql.ARQException; import org.apache.jena.sparql.core.DatasetGraph; import org.apache.jena.sparql.core.Transactional; import org.apache.jena.sparql.core.TransactionalLock; import org.apache.jena.sparql.engine.http.QueryEngineHTTP; import org.apache.jena.system.Txn; import org.apache.jena.update.UpdateFactory; import org.apache.jena.update.UpdateRequest; import org.apache.jena.web.HttpSC; /** * Implementation of the {@link RDFConnection} interface using remote SPARQL operations. */ public class RDFConnectionRemote implements RDFConnection { // Adds a Builder to help with HTTP details. private static final String fusekiDftSrvQuery = "sparql"; private static final String fusekiDftSrvUpdate = "update"; private static final String fusekiDftSrvGSP = "data"; private boolean isOpen = true; protected final String destination; protected final String svcQuery; protected final String svcUpdate; protected final String svcGraphStore; protected final Transactional txnLifecycle; protected final HttpClient httpClient; protected final HttpContext httpContext; // On-the-wire settings. protected final RDFFormat outputQuads; protected final RDFFormat outputTriples; protected final String acceptGraph; protected final String acceptDataset; protected final String acceptSparqlResults; protected final String acceptSelectResult; protected final String acceptAskResult; // Whether to check SPARQL queries given as strings by parsing them. protected final boolean parseCheckQueries; // Whether to check SPARQL updates given as strings by parsing them. protected final boolean parseCheckUpdates; /** Create a {@link RDFConnectionRemoteBuilder}. */ public static RDFConnectionRemoteBuilder create() { return new RDFConnectionRemoteBuilder(); } /** * Create a {@link RDFConnectionRemoteBuilder} initialized with the * settings of another {@code RDFConnectionRemote}. */ public static RDFConnectionRemoteBuilder create(RDFConnectionRemote base) { return new RDFConnectionRemoteBuilder(base); } /** * Create connection that will use the {@link HttpClient} using URL of the dataset and * default service names * * @deprecated Use {@link RDFConnectionRemoteBuilder}. */ @Deprecated public RDFConnectionRemote(HttpClient httpClient, String destination) { this(httpClient, requireNonNull(destination), fusekiDftSrvQuery, fusekiDftSrvUpdate, fusekiDftSrvGSP); } /** * Create connection, using URL of the dataset and default service names * * @deprecated Use {@link RDFConnectionRemoteBuilder} or an * {@link RDFConnectionFactory} operation. */ @Deprecated public RDFConnectionRemote(String destination) { this(requireNonNull(destination), fusekiDftSrvQuery, fusekiDftSrvUpdate, fusekiDftSrvGSP); } /** * Create connection, using full URLs for services. Pass a null for "no service * endpoint". * * @deprecated Use {@link RDFConnectionRemoteBuilder} or an * {@link RDFConnectionFactory} operation. */ @Deprecated public RDFConnectionRemote(String sQuery, String sUpdate, String sGSP) { this(null, sQuery, sUpdate, sGSP); } /** * Create connection, using URL of the dataset and names for the services. Short names * are expanded against the destination. Absolute URIs are left unchanged. * * @deprecated Use {@link RDFConnectionRemoteBuilder} or an * {@link RDFConnectionFactory} operation. */ @Deprecated public RDFConnectionRemote(String destination, String sQuery, String sUpdate, String sGSP) { this(null, destination, sQuery, sUpdate, sGSP); } /** * Create connection, using URL of the dataset and names for the services. Short names * are expanded against the destination. Absolute URIs are left unchanged. * * @deprecated Use {@link RDFConnectionRemoteBuilder} or an * {@link RDFConnectionFactory} operation. */ @Deprecated public RDFConnectionRemote(HttpClient httpClient, String destination, String sQuery, String sUpdate, String sGSP) { this(null, httpClient, null, destination, sQuery, sUpdate, sGSP, RDFFormat.NQUADS, RDFFormat.NTRIPLES, WebContent.defaultGraphAcceptHeader, WebContent.defaultDatasetAcceptHeader, null, QueryEngineHTTP.defaultSelectHeader(), QueryEngineHTTP.defaultAskHeader(), true, true); } // Used by the builder. protected RDFConnectionRemote(Transactional txnLifecycle, HttpClient httpClient, HttpContext httpContext, String destination, String queryURL, String updateURL, String gspURL, RDFFormat outputQuads, RDFFormat outputTriples, String acceptDataset, String acceptGraph, String acceptSparqlResults, String acceptSelectResult, String acceptAskResult, boolean parseCheckQueries, boolean parseCheckUpdates) { this.httpClient = httpClient; this.httpContext = httpContext; this.destination = destination; this.svcQuery = queryURL; this.svcUpdate = updateURL; this.svcGraphStore = gspURL; if (txnLifecycle == null) txnLifecycle = TransactionalLock.createMRPlusSW(); this.txnLifecycle = txnLifecycle; this.outputQuads = outputQuads; this.outputTriples = outputTriples; this.acceptDataset = acceptDataset; this.acceptGraph = acceptGraph; this.acceptSparqlResults = acceptSparqlResults; this.acceptSelectResult = acceptSelectResult; this.acceptAskResult = acceptAskResult; this.parseCheckQueries = parseCheckQueries; this.parseCheckUpdates = parseCheckUpdates; } /** Return the {@link HttpClient} in-use. */ public HttpClient getHttpClient() { return httpClient; } /** Return the {@link HttpContext} in-use. */ public HttpContext getHttpContext() { return httpContext; } /** Return the destination URL for the connection. */ public String getDestination() { return destination; } @Override public QueryExecution query(String queryString) { Objects.requireNonNull(queryString); return queryExec(null, queryString); } @Override public QueryExecution query(Query query) { Objects.requireNonNull(query); return queryExec(query, null); } private QueryExecution queryExec(Query query, String queryString) { checkQuery(); if (query == null && queryString == null) throw new InternalErrorException("Both query and query string are null"); if (query == null) { if (parseCheckQueries) QueryFactory.create(queryString); } // Use the query string as provided if possible, otherwise serialize the query. String queryStringToSend = (queryString != null) ? queryString : query.toString(); return exec(() -> { QueryExecution qExec = new QueryEngineHTTP(svcQuery, queryStringToSend, httpClient, httpContext); QueryEngineHTTP qEngine = (QueryEngineHTTP) qExec; // Set the accept header - use the most specific method. if (query != null) { if (query.isSelectType() && acceptSelectResult != null) qEngine.setAcceptHeader(acceptSelectResult); if (query.isAskType() && acceptAskResult != null) qEngine.setAcceptHeader(acceptAskResult); if ((query.isConstructType() || query.isDescribeType()) && acceptGraph != null) qEngine.setAcceptHeader(acceptGraph); if (query.isConstructQuad()) qEngine.setDatasetContentType(acceptDataset); } // Use the general one. if (qEngine.getAcceptHeader() == null && acceptSparqlResults != null) qEngine.setAcceptHeader(acceptSparqlResults); // Makre sure it was set somehow. if (qEngine.getAcceptHeader() == null) throw new JenaConnectionException("No Accept header"); return qExec; }); } @Override public void update(String updateString) { Objects.requireNonNull(updateString); updateExec(null, updateString); } @Override public void update(UpdateRequest update) { Objects.requireNonNull(update); updateExec(update, null); } private void updateExec(UpdateRequest update, String updateString) { checkUpdate(); if (update == null && updateString == null) throw new InternalErrorException("Both update request and update string are null"); if (update == null) { if (parseCheckUpdates) UpdateFactory.create(updateString); } // Use the update string as provided if possible, otherwise serialize the update. String updateStringToSend = (updateString != null) ? updateString : update.toString(); exec(() -> HttpOp.execHttpPost(svcUpdate, WebContent.contentTypeSPARQLUpdate, updateStringToSend, this.httpClient, this.httpContext)); } @Override public Model fetch(String graphName) { checkGSP(); String url = LibRDFConn.urlForGraph(svcGraphStore, graphName); Graph graph = fetch$(url); return ModelFactory.createModelForGraph(graph); } @Override public Model fetch() { checkGSP(); return fetch(null); } private Graph fetch$(String url) { HttpCaptureResponse<Graph> graph = HttpResponseLib.graphHandler(); exec(() -> HttpOp.execHttpGet(url, acceptGraph, graph, this.httpClient, this.httpContext)); return graph.get(); } @Override public void load(String graph, String file) { checkGSP(); upload(graph, file, false); } @Override public void load(String file) { checkGSP(); upload(null, file, false); } @Override public void load(Model model) { doPutPost(model, null, false); } @Override public void load(String graphName, Model model) { doPutPost(model, graphName, false); } @Override public void put(String graph, String file) { checkGSP(); upload(graph, file, true); } @Override public void put(String file) { checkGSP(); upload(null, file, true); } @Override public void put(String graphName, Model model) { checkGSP(); doPutPost(model, graphName, true); } @Override public void put(Model model) { checkGSP(); doPutPost(model, null, true); } /** Send a file to named graph (or "default" or null for the default graph). * <p> * The Content-Type is inferred from the file extension. * <p> * "Replace" means overwrite existing data, othewise the date is added to the target. */ protected void upload(String graph, String file, boolean replace) { // if triples Lang lang = RDFLanguages.filenameToLang(file); if (RDFLanguages.isQuads(lang)) throw new ARQException("Can't load quads into a graph"); if (!RDFLanguages.isTriples(lang)) throw new ARQException("Not an RDF format: " + file + " (lang=" + lang + ")"); String url = LibRDFConn.urlForGraph(svcGraphStore, graph); doPutPost(url, file, lang, replace); } /** Send a file to named graph (or "default" or null for the defaultl graph). * <p> * The Content-Type is taken from the given {@code Lang}. * <p> * "Replace" means overwrite existing data, othewise the date is added to the target. */ protected void doPutPost(String url, String file, Lang lang, boolean replace) { File f = new File(file); long length = f.length(); InputStream source = IO.openFile(file); // Charset. exec(() -> { if (replace) HttpOp.execHttpPut(url, lang.getContentType().getContentType(), source, length, httpClient, this.httpContext); else HttpOp.execHttpPost(url, lang.getContentType().getContentType(), source, length, null, null, httpClient, this.httpContext); }); } /** Send a model to named graph (or "default" or null for the defaultl graph). * <p> * The Content-Type is taken from the given {@code Lang}. * <p> * "Replace" means overwrite existing data, othewise the date is added to the target. */ protected void doPutPost(Model model, String name, boolean replace) { String url = LibRDFConn.urlForGraph(svcGraphStore, name); exec(() -> { Graph graph = model.getGraph(); if (replace) HttpOp.execHttpPut(url, graphToHttpEntity(graph), httpClient, this.httpContext); else HttpOp.execHttpPost(url, graphToHttpEntity(graph), null, null, httpClient, this.httpContext); }); } @Override public void delete(String graph) { checkGSP(); String url = LibRDFConn.urlForGraph(svcGraphStore, graph); exec(() -> HttpOp.execHttpDelete(url)); } @Override public void delete() { checkGSP(); delete(null); } @Override public Dataset fetchDataset() { if (destination == null) throw new ARQException("Dataset operations not available - no dataset URL provided"); Dataset ds = DatasetFactory.createTxnMem(); Txn.executeWrite(ds, () -> { TypedInputStream s = exec(() -> HttpOp.execHttpGet(destination, acceptDataset)); Lang lang = RDFLanguages.contentTypeToLang(s.getContentType()); RDFDataMgr.read(ds, s, lang); }); return ds; } @Override public void loadDataset(String file) { if (destination == null) throw new ARQException("Dataset operations not available - no dataset URl provided"); doPutPostDataset(file, false); } @Override public void loadDataset(Dataset dataset) { if (destination == null) throw new ARQException("Dataset operations not available - no dataset URl provided"); doPutPostDataset(dataset, false); } @Override public void putDataset(String file) { if (destination == null) throw new ARQException("Dataset operations not available - no dataset URl provided"); doPutPostDataset(file, true); } @Override public void putDataset(Dataset dataset) { if (destination == null) throw new ARQException("Dataset operations not available - no dataset URl provided"); doPutPostDataset(dataset, true); } /** Do a PUT or POST to a dataset, sending the contents of the file. * <p> * The Content-Type is inferred from the file extension. * <p> * "Replace" implies PUT, otherwise a POST is used. */ protected void doPutPostDataset(String file, boolean replace) { Lang lang = RDFLanguages.filenameToLang(file); File f = new File(file); long length = f.length(); exec(() -> { InputStream source = IO.openFile(file); if (replace) HttpOp.execHttpPut(destination, lang.getContentType().getContentType(), source, length, httpClient, httpContext); else HttpOp.execHttpPost(destination, lang.getContentType().getContentType(), source, length, null, null, httpClient, httpContext); }); } /** Do a PUT or POST to a dataset, sending the contents of a daatsets. * The Content-Type is {@code application/n-quads}. * <p> * "Replace" implies PUT, otherwise a POST is used. */ protected void doPutPostDataset(Dataset dataset, boolean replace) { exec(() -> { DatasetGraph dsg = dataset.asDatasetGraph(); if (replace) HttpOp.execHttpPut(destination, datasetToHttpEntity(dsg), httpClient, null); else HttpOp.execHttpPost(destination, datasetToHttpEntity(dsg), httpClient, null); }); } protected void checkQuery() { checkOpen(); if (svcQuery == null) throw new ARQException("No query service defined for this RDFConnection"); } protected void checkUpdate() { checkOpen(); if (svcUpdate == null) throw new ARQException("No update service defined for this RDFConnection"); } protected void checkGSP() { checkOpen(); if (svcGraphStore == null) throw new ARQException("No SPARQL Graph Store service defined for this RDFConnection"); } protected void checkDataset() { checkOpen(); if (destination == null) throw new ARQException("Dataset operations not available - no dataset URL provided"); } protected void checkOpen() { if (!isOpen) throw new ARQException("closed"); } @Override public void close() { isOpen = false; } @Override public boolean isClosed() { return !isOpen; } /** Create an HttpEntity for the graph */ protected HttpEntity graphToHttpEntity(Graph graph) { return graphToHttpEntity(graph, outputTriples); } /** Create an HttpEntity for the graph */ protected HttpEntity graphToHttpEntity(Graph graph, RDFFormat syntax) { EntityTemplate entity = new EntityTemplate((out) -> RDFDataMgr.write(out, graph, syntax)); String ct = syntax.getLang().getContentType().getContentType(); entity.setContentType(ct); return entity; } /** Create an HttpEntity for the dataset */ protected HttpEntity datasetToHttpEntity(DatasetGraph dataset) { return datasetToHttpEntity(dataset, outputQuads); } /** Create an HttpEntity for the dataset */ protected HttpEntity datasetToHttpEntity(DatasetGraph dataset, RDFFormat syntax) { EntityTemplate entity = new EntityTemplate((out) -> RDFDataMgr.write(out, dataset, syntax)); String ct = syntax.getLang().getContentType().getContentType(); entity.setContentType(ct); return entity; } /** Convert HTTP status codes to exceptions */ static protected void exec(Runnable action) { try { action.run(); } catch (HttpException ex) { handleHttpException(ex, false); } } /** Convert HTTP status codes to exceptions */ static protected <X> X exec(Supplier<X> action) { try { return action.get(); } catch (HttpException ex) { handleHttpException(ex, true); return null; } } private static void handleHttpException(HttpException ex, boolean ignore404) { if (ex.getResponseCode() == HttpSC.NOT_FOUND_404 && ignore404) return; throw ex; } @Override public void begin() { txnLifecycle.begin(); } @Override public void begin(TxnType txnType) { txnLifecycle.begin(txnType); } @Override public void begin(ReadWrite mode) { txnLifecycle.begin(mode); } @Override public boolean promote(Promote promote) { return txnLifecycle.promote(promote); } @Override public void commit() { txnLifecycle.commit(); } @Override public void abort() { txnLifecycle.abort(); } @Override public boolean isInTransaction() { return txnLifecycle.isInTransaction(); } @Override public void end() { txnLifecycle.end(); } @Override public ReadWrite transactionMode() { return txnLifecycle.transactionMode(); } @Override public TxnType transactionType() { return txnLifecycle.transactionType(); } }