net.myrrix.web.servlets.EstimateForAnonymousServlet.java Source code

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Here is the source code for net.myrrix.web.servlets.EstimateForAnonymousServlet.java

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/*
 * Copyright Myrrix Ltd
 *
 * 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 net.myrrix.web.servlets;

import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.math3.util.Pair;
import org.apache.mahout.cf.taste.common.NoSuchItemException;
import org.apache.mahout.cf.taste.common.TasteException;

import net.myrrix.common.MyrrixRecommender;
import net.myrrix.common.NotReadyException;

/**
 * <p>Responds to a GET request to
 * {@code /estimateForAnonymous/[toItemID]/[itemID1(=value1)](/[itemID2(=value2)]/...)},
 * and in turn calls {@link MyrrixRecommender#estimateForAnonymous(long, long[], float[])}
 * with the supplied values. That is, 1 or more item IDs are supplied, which may each optionally correspond to
 * a value or else default to 1.</p>
 *
 * <p>Unknown item IDs are ignored, unless all are unknown, in which case a
 * {@link HttpServletResponse#SC_BAD_REQUEST} status is returned.</p>
 *
 * <p>Outputs the result of the method call as a value on one line.</p>
 *
 * @author Sean Owen
 * @since 1.0
 */
public final class EstimateForAnonymousServlet extends AbstractMyrrixServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {

        CharSequence pathInfo = request.getPathInfo();
        if (pathInfo == null) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No path");
            return;
        }
        Iterator<String> pathComponents = SLASH.split(pathInfo).iterator();
        long toItemID;
        Pair<long[], float[]> itemIDsAndValue;
        try {
            toItemID = Long.parseLong(pathComponents.next());
            itemIDsAndValue = RecommendToAnonymousServlet.parseItemValuePairs(pathComponents);
        } catch (NoSuchElementException nsee) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, nsee.toString());
            return;
        } catch (NumberFormatException nfe) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, nfe.toString());
            return;
        }

        if (itemIDsAndValue.getFirst().length == 0) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST, "No items");
            return;
        }

        long[] itemIDs = itemIDsAndValue.getFirst();
        float[] values = itemIDsAndValue.getSecond();

        MyrrixRecommender recommender = getRecommender();
        try {
            float estimate = recommender.estimateForAnonymous(toItemID, itemIDs, values);
            Writer out = response.getWriter();
            out.write(Float.toString(estimate));
            out.write('\n');
        } catch (NotReadyException nre) {
            response.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE, nre.toString());
        } catch (NoSuchItemException nsie) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND, nsie.toString());
        } catch (TasteException te) {
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, te.toString());
            getServletContext().log("Unexpected error in " + getClass().getSimpleName(), te);
        }
    }

}