RepresentationVersionAddedPersistentMessageProcessor.java

package eu.europeana.cloud.service.dls.listeners;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.reflect.TypeToken;
import eu.europeana.cloud.common.model.Representation;
import eu.europeana.cloud.common.web.ParamConstants;
import eu.europeana.cloud.common.model.CompoundDataSetId;
import eu.europeana.cloud.service.dls.solr.SolrDAO;
import eu.europeana.cloud.service.mcs.messages.InsertRepresentationPersistentMessage;
import java.io.IOException;
import java.lang.reflect.Type;
import java.util.Collection;
import org.apache.solr.client.solrj.SolrServerException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

/**
 * Processor that processes messages about adding a new persistent
 * {@link eu.europeana.cloud.common.model.Representation representation} version
 * to a certain {@link eu.europeana.cloud.common.model.Record record}.
 * 
 * It processes messages with
 * <code>records.representations.versions.addPersistent</code> routing key.
 * Message text should be a map serialised to Json, holding
 * {@link Representation} object, and a list of {@link CompoundDataSetId}
 * objects. The list of ids is needed, if there are some
 * {@link eu.europeana.cloud.common.model.DataSet data sets} that have
 * representation name assigned <i>as a whole</i>. In such case
 * {@link eu.europeana.cloud.common.model.DataSet data set} holds a pointer to
 * latest persistent version. So if a new version is persisted, the pointer
 * might need to be updated (not necessarily, because <i>latest</i> property is
 * attributed based on {@link eu.europeana.cloud.common.model.Representation
 * representation} creation time). The list of ids can be empty, but cannot be
 * <code>null</code>.
 * 
 * After processing properly formed message, processor calls
 * {@link eu.europeana.cloud.service.dls.solr.SolrDAO#insertRepresentation(Representation, Collection)
 * SolrDAO.insertRepresentation(Representation,
 * Collection<CompoundDataSetId>)} so that Solr index is updated (the
 * {@link eu.europeana.cloud.common.model.Representation representation} is
 * marked as persistent and {@link eu.europeana.cloud.common.model.DataSet data
 * sets} point to this {@link eu.europeana.cloud.common.model.Representation
 * representation} if appropriate).
 * 
 * If message is malformed, information about error is logged and no call to
 * {@link eu.europeana.cloud.service.dls.solr.SolrDAO} is performed. If call to
 * {@link eu.europeana.cloud.service.dls.solr.SolrDAO} fails, an information is
 * also logged.
 * 
 * Messages for this processor are produced by
 * <code>eu.europeana.cloud.service.mcs.persistent.SolrRepresentationIndexer.insertRepresentation(Representation, Collection<CompoundDataSetId>)</code>
 * method in MCS.
 */
@Component
public class RepresentationVersionAddedPersistentMessageProcessor implements
	MessageProcessor<InsertRepresentationPersistentMessage> {

    private static final Logger LOGGER = LoggerFactory
	    .getLogger(RepresentationVersionAddedPersistentMessageProcessor.class);
    private static final Gson gson = new GsonBuilder().setDateFormat(
	    "yyyy-MM-dd'T'HH:mm:ss.SSSZZ").create();

    @Autowired
    SolrDAO solrDao;

    @Override
    public void processMessage(InsertRepresentationPersistentMessage message) {
        String messageText = message.getPayload();
        
        if (messageText == null || messageText.isEmpty()) {
            LOGGER.error("Message has empty body.");
            return;
        }

        JsonElement jsonElem = gson.fromJson(messageText, JsonElement.class);
        if (jsonElem == null || jsonElem.isJsonNull()) {
            LOGGER.error("Received message with null parameters map.");
            return;
        }
        JsonObject jsonObject = jsonElem.getAsJsonObject();

        JsonElement jsonRepresentation = jsonObject.get(ParamConstants.F_REPRESENTATION);
        Representation representation = gson.fromJson(jsonRepresentation, Representation.class);
        if (representation == null) {
            LOGGER.error("Received representation is null.");
            return;
        }

        Type dataSetIdsType = new TypeToken<Collection<CompoundDataSetId>>() {
        }.getType();
        JsonElement jsonDataSetIds = jsonObject.get(ParamConstants.F_DATASETS);
        Collection<CompoundDataSetId> dataSetIds = gson.fromJson(jsonDataSetIds, dataSetIdsType);
        if (dataSetIds == null) {
            LOGGER.error("Received data set ids list is null.");
            return;
        }

        try {
            solrDao.insertRepresentation(representation, dataSetIds);
        } catch (IOException | SolrServerException ex) {
            LOGGER.error("Cannot insert persistent representation into solr.", ex);
        }
    }
}