MET-6139 Move rdf convertion classes from metis-framework. #14
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| package eu.europeana.metis.schema.convert; | ||
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| import static eu.europeana.metis.schema.convert.model.RdfXpathConstants.EDM_HAS_VIEW; | ||
| import static eu.europeana.metis.schema.convert.model.RdfXpathConstants.EDM_IS_SHOWN_AT; | ||
| import static eu.europeana.metis.schema.convert.model.RdfXpathConstants.EDM_IS_SHOWN_BY; | ||
| import static eu.europeana.metis.schema.convert.model.RdfXpathConstants.EDM_OBJECT; | ||
| import static eu.europeana.metis.schema.convert.model.RdfXpathConstants.EDM_WEBRESOURCE; | ||
| import static eu.europeana.metis.schema.convert.model.RdfXpathConstants.SVCS_SERVICE; | ||
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| import eu.europeana.metis.schema.convert.model.DeserializationOperation; | ||
| import eu.europeana.metis.schema.convert.model.RdfDeserializationException; | ||
| import eu.europeana.metis.schema.convert.model.RdfResourceEntry; | ||
| import eu.europeana.metis.schema.convert.model.ResourceInfo; | ||
| import eu.europeana.metis.schema.convert.model.UrlType; | ||
| import eu.europeana.metis.schema.convert.model.XPathExpressionWrapper; | ||
| import eu.europeana.metis.schema.jibx.RDF; | ||
| import java.io.ByteArrayInputStream; | ||
| import java.io.IOException; | ||
| import java.io.InputStream; | ||
| import java.nio.charset.StandardCharsets; | ||
| import java.util.Collections; | ||
| import java.util.HashMap; | ||
| import java.util.HashSet; | ||
| import java.util.List; | ||
| import java.util.Map; | ||
| import java.util.Map.Entry; | ||
| import java.util.Optional; | ||
| import java.util.Set; | ||
| import java.util.stream.Collectors; | ||
| import java.util.stream.IntStream; | ||
| import javax.xml.XMLConstants; | ||
| import javax.xml.parsers.DocumentBuilderFactory; | ||
| import javax.xml.parsers.ParserConfigurationException; | ||
| import org.jibx.runtime.BindingDirectory; | ||
| import org.jibx.runtime.IBindingFactory; | ||
| import org.jibx.runtime.IUnmarshallingContext; | ||
| import org.jibx.runtime.JiBXException; | ||
| import org.w3c.dom.Document; | ||
| import org.w3c.dom.Node; | ||
| import org.w3c.dom.NodeList; | ||
| import org.xml.sax.SAXException; | ||
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| public class RdfDeserializer { | ||
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| private static final String UTF8 = StandardCharsets.UTF_8.name(); | ||
| private static final String OEMBED_NAMESPACE = "https://oembed.com/"; | ||
| private static final String XPATH_OEMBED_SERVICES = | ||
| SVCS_SERVICE + "[dcterms:conformsTo/@rdf:resource = \"" + OEMBED_NAMESPACE + "\"]"; | ||
| private static final String XPATH_OEMBED_WEB_RESOURCES = EDM_WEBRESOURCE | ||
| + "[svcs:has_service/@rdf:resource = " + XPATH_OEMBED_SERVICES + "/@rdf:about]"; | ||
| private static final String XPATH_IS_OEMBED_RESOURCE_CONDITION = "[. = " | ||
| + XPATH_OEMBED_WEB_RESOURCES + "/@rdf:about]"; | ||
| private static final String OEMBED_XPATH_CONDITION_IS_SHOWN_BY = | ||
| EDM_IS_SHOWN_BY + XPATH_IS_OEMBED_RESOURCE_CONDITION; | ||
| private static final String OEMBED_XPATH_CONDITION_HAS_VIEW = | ||
| EDM_HAS_VIEW + XPATH_IS_OEMBED_RESOURCE_CONDITION; | ||
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| private final XPathExpressionWrapper getObjectExpression = new XPathExpressionWrapper(xPath -> xPath.compile(EDM_OBJECT)); | ||
| private final XPathExpressionWrapper getHasViewExpression = new XPathExpressionWrapper(xPath -> xPath.compile(EDM_HAS_VIEW)); | ||
| private final XPathExpressionWrapper getIsShownAtExpression = new XPathExpressionWrapper( | ||
| xPath -> xPath.compile(EDM_IS_SHOWN_AT)); | ||
| private final XPathExpressionWrapper getIsShownByExpression = new XPathExpressionWrapper( | ||
| xPath -> xPath.compile(EDM_IS_SHOWN_BY)); | ||
| private final XPathExpressionWrapper getOEmbedExpression = new XPathExpressionWrapper( | ||
| xPath -> xPath.compile(OEMBED_XPATH_CONDITION_HAS_VIEW + " | " + OEMBED_XPATH_CONDITION_IS_SHOWN_BY)); | ||
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| private final IBindingFactory rdfBindingFactory; | ||
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| /** | ||
| * Default constructor | ||
| */ | ||
| public RdfDeserializer() { | ||
| this(RDF.class); | ||
| } | ||
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| /** | ||
| * Constructor supplying class type for the binding factory. | ||
| * <p>At the current state this is used for assisting testing</p> | ||
| * | ||
| * @param classType the class object type | ||
| * @param <T> the class type | ||
| */ | ||
| <T> RdfDeserializer(Class<T> classType) { | ||
| try { | ||
| rdfBindingFactory = BindingDirectory.getFactory(classType); | ||
| } catch (JiBXException e) { | ||
| throw new IllegalStateException("No binding factory available.", e); | ||
| } | ||
| } | ||
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| /** | ||
| * Convert a UTF-8 encoded XML to {@link RDF} | ||
| * | ||
| * @param xml the xml string | ||
| * @return the RDF object | ||
| * @throws RdfDeserializationException if during unmarshalling there is a failure | ||
| */ | ||
| public RDF deserialize(String xml) throws RdfDeserializationException { | ||
| try (final InputStream inputStream = new ByteArrayInputStream( | ||
| xml.getBytes(StandardCharsets.UTF_8))) { | ||
| return deserialize(inputStream); | ||
| } catch (IOException e) { | ||
| throw new RdfDeserializationException("Unexpected issue with byte stream.", e); | ||
| } | ||
| } | ||
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| /** | ||
| * Convert a UTF-8 encoded XML to {@link RDF} | ||
| * | ||
| * @param inputStream The xml. The stream is not closed. | ||
| * @return the RDF object | ||
| * @throws RdfDeserializationException if during unmarshalling there is a failure | ||
| */ | ||
| public RDF deserialize(InputStream inputStream) throws RdfDeserializationException { | ||
| try { | ||
| final IUnmarshallingContext context = rdfBindingFactory.createUnmarshallingContext(); | ||
| return (RDF) context.unmarshalDocument(inputStream, UTF8); | ||
| } catch (JiBXException e) { | ||
| throw new RdfDeserializationException( | ||
| "Something went wrong with converting to or from the RDF format.", e); | ||
| } | ||
| } | ||
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| public Document deserializeToDocument(InputStream inputStream) throws RdfDeserializationException { | ||
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| // Parse document to schema-agnostic XML document (but make parsing namespace-aware). | ||
| try { | ||
| final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); | ||
| factory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true); | ||
| factory.setFeature("http://apache.org/xml/features/disallow-doctype-decl", true); | ||
| factory.setNamespaceAware(true); | ||
| return factory.newDocumentBuilder().parse(inputStream); | ||
| } catch (SAXException | IOException | ParserConfigurationException e) { | ||
| throw new RdfDeserializationException("Problem with deserializing record to XML document.", e); | ||
| } | ||
| } | ||
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| public RdfResourceEntry getMainThumbnailResource(byte[] input) throws RdfDeserializationException { | ||
| return performDeserialization(input, this::getMainThumbnailResource); | ||
| } | ||
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| public RdfResourceEntry getMainThumbnailResource(InputStream inputStream) | ||
| throws RdfDeserializationException { | ||
| return getMainThumbnailResource(deserializeToDocument(inputStream)).orElse(null); | ||
| } | ||
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| public Optional<RdfResourceEntry> getMainThumbnailResource(Document document) | ||
| throws RdfDeserializationException { | ||
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| // Get the entries of the required types. | ||
| final Map<String, ResourceInfo> resourceEntries = getResourceEntries(document, | ||
| Collections.singleton(UrlType.URL_TYPE_FOR_MAIN_THUMBNAIL_RESOURCE)); | ||
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| // If there is not exactly one, we return an empty optional. | ||
| if (resourceEntries.size() != 1) { | ||
| return Optional.empty(); | ||
| } | ||
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| // So there is exactly one. Convert and return. | ||
| return Optional.of(convertToResourceEntries(resourceEntries).get(0)); | ||
| } | ||
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| public List<RdfResourceEntry> convertToResourceEntries( | ||
| Map<String, ResourceInfo> urlWithTypes) { | ||
| return urlWithTypes.entrySet().stream().map(RdfDeserializer::convertToResourceEntry) | ||
| .toList(); | ||
| } | ||
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| private static RdfResourceEntry convertToResourceEntry(Map.Entry<String, ResourceInfo> entry) { | ||
| return new RdfResourceEntry(entry.getKey(), entry.getValue().urlTypes(), | ||
| entry.getValue().configuredForOembed()); | ||
| } | ||
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| /** | ||
| * Gets resource entries. | ||
| * | ||
| * @param document the document | ||
| * @param allowedUrlTypes the allowed url types | ||
| * @return the resource entries | ||
| * @throws RdfDeserializationException the rdf deserialization exception | ||
| */ | ||
| public Map<String, ResourceInfo> getResourceEntries(Document document, | ||
| Set<UrlType> allowedUrlTypes) throws RdfDeserializationException { | ||
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| // Get the resources and their types. | ||
| final Map<String, Set<UrlType>> urls = new HashMap<>(); | ||
| for (UrlType type : allowedUrlTypes) { | ||
| final Set<String> urlsForType = getUrls(document, type); | ||
| for (String url : urlsForType) { | ||
| urls.computeIfAbsent(url, k -> new HashSet<>()).add(type); | ||
| } | ||
| } | ||
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| // For each resource, check whether they are configured for oEmbed. | ||
| final Map<String, ResourceInfo> result = HashMap.newHashMap(urls.size()); | ||
| final Set<String> oEmbedUrls = getOEmbedUrls(document); | ||
| for (Entry<String, Set<UrlType>> entry : urls.entrySet()) { | ||
| boolean isConfiguredForOembed = oEmbedUrls.contains(entry.getKey()); | ||
| result.put(entry.getKey(), new ResourceInfo(entry.getValue(), isConfiguredForOembed)); | ||
| } | ||
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| // Done | ||
| return result; | ||
| } | ||
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| private Set<String> getUrls(Document document, UrlType type) throws RdfDeserializationException { | ||
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| // Determine the right expression to apply. | ||
| final XPathExpressionWrapper expression = | ||
| switch (type) { | ||
| case OBJECT -> getObjectExpression; | ||
| case HAS_VIEW -> getHasViewExpression; | ||
| case IS_SHOWN_AT -> getIsShownAtExpression; | ||
| case IS_SHOWN_BY -> getIsShownByExpression; | ||
| }; | ||
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| // Evaluate the expression and convert the node list to a set of attribute values. | ||
| final NodeList nodes = expression.evaluate(document); | ||
| return IntStream.range(0, nodes.getLength()).mapToObj(nodes::item).map(Node::getNodeValue) | ||
| .collect(Collectors.toSet()); | ||
| } | ||
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| private Set<String> getOEmbedUrls(Document document) throws RdfDeserializationException { | ||
| final NodeList oEmbedNodes = getOEmbedExpression.evaluate(document); | ||
| return IntStream.range(0, oEmbedNodes.getLength()) | ||
| .mapToObj(oEmbedNodes::item) | ||
| .map(Node::getNodeValue) | ||
| .collect(Collectors.toSet()); | ||
| } | ||
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| public <R> R performDeserialization(byte[] input, DeserializationOperation<R> operation) | ||
| throws RdfDeserializationException { | ||
| try (InputStream inputStream = new ByteArrayInputStream(input)) { | ||
| return operation.performDeserialization(inputStream); | ||
| } catch (IOException e) { | ||
| throw new RdfDeserializationException("Problem with reading byte array - Shouldn't happen.", e); | ||
| } | ||
| } | ||
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| } | ||
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