com.buddycloud.channeldirectory.search.handler.similarity.SimilarityQueryHandler.java Source code

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Here is the source code for com.buddycloud.channeldirectory.search.handler.similarity.SimilarityQueryHandler.java

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/*
 * Copyright 2011 buddycloud
 *
 * Licensed 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 com.buddycloud.channeldirectory.search.handler.similarity;

import java.sql.SQLException;
import java.util.List;
import java.util.Properties;

import org.apache.mahout.cf.taste.common.TasteException;
import org.dom4j.Element;
import org.xmpp.packet.IQ;

import com.buddycloud.channeldirectory.search.handler.common.ChannelQueryHandler;
import com.buddycloud.channeldirectory.search.handler.common.mahout.ChannelRecommender;
import com.buddycloud.channeldirectory.search.handler.common.mahout.RecommendationResponse;
import com.buddycloud.channeldirectory.search.handler.response.ChannelData;
import com.buddycloud.channeldirectory.search.rsm.MahoutRSMUtils;
import com.buddycloud.channeldirectory.search.rsm.RSM;
import com.buddycloud.channeldirectory.search.rsm.RSMUtils;
import com.buddycloud.channeldirectory.search.utils.XMPPUtils;

/**
 * Handles queries for user recommendation.
 * A query should contain an user jid, so
 * this handler can return recommended channels 
 * to this given user.
 *  
 */
public class SimilarityQueryHandler extends ChannelQueryHandler {

    private static final int DEFAULT_PAGE = 10;
    private final ChannelRecommender recommender;

    public SimilarityQueryHandler(Properties properties, ChannelRecommender recommender) {
        super("http://buddycloud.com/channel_directory/similar_channels", properties);
        this.recommender = recommender;
    }

    @Override
    public IQ handle(IQ iq) {

        Element queryElement = iq.getElement().element("query");
        Element channelJidElement = queryElement.element("channel-jid");

        if (channelJidElement == null) {
            return XMPPUtils.error(iq, "Query does not contain channel-jid element.", getLogger());
        }

        String channelJid = channelJidElement.getText();

        if (channelJid == null || channelJid.isEmpty()) {
            return XMPPUtils.error(iq, "Channel-jid cannot be empty.", getLogger());
        }

        RSM rsm = RSMUtils.parseRSM(queryElement);
        rsm.setMax(rsm.getMax() != null ? rsm.getMax() : DEFAULT_PAGE);

        List<ChannelData> similarChannels;
        try {
            similarChannels = findSimilarChannels(channelJid, rsm);
        } catch (Exception e) {
            return XMPPUtils.error(iq, "Search could not be performed, service is unavailable.", e, getLogger());
        }

        List<ChannelData> similarChannelsFullData;
        try {
            similarChannelsFullData = retrieveFromSolr(similarChannels);
        } catch (Exception e) {
            return XMPPUtils.error(iq, "Search could not be performed, service is unavailable.", e, getLogger());
        }

        return createIQResponse(iq, similarChannelsFullData, rsm);
    }

    private List<ChannelData> findSimilarChannels(String search, RSM rsm) throws TasteException, SQLException {
        int howMany = MahoutRSMUtils.preprocess(rsm);
        RecommendationResponse recommendationResponse = recommender.getSimilarChannels(search, howMany);
        return MahoutRSMUtils.postprocess(recommendationResponse, rsm);
    }
}