com.buddycloud.channeldirectory.search.handler.recommendation.RecommendationQueryHandler.java Source code

Introduction

Here is the source code for com.buddycloud.channeldirectory.search.handler.recommendation.RecommendationQueryHandler.java

Source

/*
 * 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.recommendation;

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 RecommendationQueryHandler extends ChannelQueryHandler {

    private static final int DEFAULT_PAGE = 10;

    private final ChannelRecommender recommender;

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

    @Override
    public IQ handle(IQ iq) {

        Element queryElement = iq.getElement().element("query");
        Element userJidElement = queryElement.element("user-jid");

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

        String userJid = userJidElement.getText();

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

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

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

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

        return createIQResponse(iq, recommendedChannelsFullData, rsm);
    }

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