org.apache.asterix.api.http.servlet.QueryResultAPIServlet Maven / Gradle / Ivy

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.asterix.api.http.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.JSONArray;
import org.json.JSONObject;

import org.apache.asterix.api.common.SessionConfig;
import org.apache.asterix.result.ResultReader;
import org.apache.asterix.result.ResultUtils;
import org.apache.hyracks.api.client.HyracksConnection;
import org.apache.hyracks.api.client.IHyracksClientConnection;
import org.apache.hyracks.api.dataset.IHyracksDataset;
import org.apache.hyracks.api.dataset.ResultSetId;
import org.apache.hyracks.api.job.JobId;
import org.apache.hyracks.client.dataset.HyracksDataset;

public class QueryResultAPIServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    private static final String HYRACKS_CONNECTION_ATTR = "org.apache.asterix.HYRACKS_CONNECTION";

    private static final String HYRACKS_DATASET_ATTR = "org.apache.asterix.HYRACKS_DATASET";

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
        response.setContentType("text/html");
        response.setCharacterEncoding("utf-8");
        String strHandle = request.getParameter("handle");
        PrintWriter out = response.getWriter();
        ServletContext context = getServletContext();
        IHyracksClientConnection hcc;
        IHyracksDataset hds;

        try {
            HyracksProperties hp = new HyracksProperties();
            String strIP = hp.getHyracksIPAddress();
            int port = hp.getHyracksPort();

            synchronized (context) {
                hcc = (IHyracksClientConnection) context.getAttribute(HYRACKS_CONNECTION_ATTR);
                if (hcc == null) {
                    hcc = new HyracksConnection(strIP, port);
                    context.setAttribute(HYRACKS_CONNECTION_ATTR, hcc);
                }

                hds = (IHyracksDataset) context.getAttribute(HYRACKS_DATASET_ATTR);
                if (hds == null) {
                    hds = new HyracksDataset(hcc, ResultReader.FRAME_SIZE, ResultReader.NUM_READERS);
                    context.setAttribute(HYRACKS_DATASET_ATTR, hds);
                }
            }
            JSONObject handleObj = new JSONObject(strHandle);
            JSONArray handle = handleObj.getJSONArray("handle");
            JobId jobId = new JobId(handle.getLong(0));
            ResultSetId rsId = new ResultSetId(handle.getLong(1));

            ResultReader resultReader = new ResultReader(hcc, hds);
            resultReader.open(jobId, rsId);

            // QQQ The output format is determined by the initial
            // query and cannot be modified here, so calling back to
            // initResponse() is really an error. We need to find a
            // way to send the same OutputFormat value here as was
            // originally determined there. Need to save this value on
            // some object that we can obtain here.
            SessionConfig sessionConfig = RESTAPIServlet.initResponse(request, response);
            ResultUtils.displayResults(resultReader, sessionConfig);

        } catch (Exception e) {
            out.println(e.getMessage());
            e.printStackTrace(out);
        }
    }
}