JsonSerializer.java

/**
 * 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.storm.multilang;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.ParseException;

import org.apache.storm.task.TopologyContext;
import org.apache.storm.utils.Utils;

/**
 * JsonSerializer implements the JSON multilang protocol.
 */
public class JsonSerializer implements ISerializer {
    //ANY CHANGE TO THIS CODE MUST BE SERIALIZABLE COMPATIBLE OR THERE WILL BE PROBLEMS
    private static final long serialVersionUID = 2548814660410474022L;

    public static final String DEFAULT_CHARSET = "UTF-8";

    private transient BufferedWriter processIn;
    private transient BufferedReader processOut;

    public void initialize(OutputStream processIn, InputStream processOut) {
        try {
            this.processIn = new BufferedWriter(new OutputStreamWriter(processIn, DEFAULT_CHARSET));
            this.processOut = new BufferedReader(new InputStreamReader(processOut, DEFAULT_CHARSET));
        } catch (UnsupportedEncodingException e) {
            throw new RuntimeException(e);
        }
    }

    public Number connect(Map conf, TopologyContext context)
            throws IOException, NoOutputException {
        JSONObject setupInfo = new JSONObject();
        setupInfo.put("pidDir", context.getPIDDir());
        setupInfo.put("conf", conf);
        setupInfo.put("context", context);
        writeMessage(setupInfo);

        Number pid = (Number) ((JSONObject) readMessage()).get("pid");
        return pid;
    }

    public void writeBoltMsg(BoltMsg boltMsg) throws IOException {
        JSONObject obj = new JSONObject();
        obj.put("id", boltMsg.getId());
        obj.put("comp", boltMsg.getComp());
        obj.put("stream", boltMsg.getStream());
        obj.put("task", boltMsg.getTask());
        obj.put("tuple", boltMsg.getTuple());
        writeMessage(obj);
    }

    public void writeSpoutMsg(SpoutMsg msg) throws IOException {
        JSONObject obj = new JSONObject();
        obj.put("command", msg.getCommand());
        obj.put("id", msg.getId());
        writeMessage(obj);
    }

    public void writeTaskIds(List<Integer> taskIds) throws IOException {
        writeMessage(taskIds);
    }

    private void writeMessage(Object msg) throws IOException {
        writeString(JSONValue.toJSONString(msg));
    }

    private void writeString(String str) throws IOException {
        processIn.write(str);
        processIn.write("\nend\n");
        processIn.flush();
    }

    public ShellMsg readShellMsg() throws IOException, NoOutputException {
        JSONObject msg = (JSONObject) readMessage();
        ShellMsg shellMsg = new ShellMsg();

        String command = (String) msg.get("command");
        shellMsg.setCommand(command);

        Object id = msg.get("id");
        shellMsg.setId(id);

        String log = (String) msg.get("msg");
        shellMsg.setMsg(log);

        String stream = (String) msg.get("stream");
        if (stream == null)
            stream = Utils.DEFAULT_STREAM_ID;
        shellMsg.setStream(stream);

        Object taskObj = msg.get("task");
        if (taskObj != null) {
            shellMsg.setTask((Long) taskObj);
        } else {
            shellMsg.setTask(0);
        }

        Object need_task_ids = msg.get("need_task_ids");
        if (need_task_ids == null || ((Boolean) need_task_ids).booleanValue()) {
            shellMsg.setNeedTaskIds(true);
        } else {
            shellMsg.setNeedTaskIds(false);
        }

        shellMsg.setTuple((List) msg.get("tuple"));

        Object anchorObj = msg.get("anchors");
        if (anchorObj != null) {
            if (anchorObj instanceof String) {
                anchorObj = Arrays.asList(anchorObj);
            }
            for (Object o : (List) anchorObj) {
                shellMsg.addAnchor((String) o);
            }
        }
       
        Object nameObj = msg.get("name"); 
        String metricName = null;
        if (nameObj != null && nameObj instanceof String) {
            metricName = (String) nameObj;
        }
        shellMsg.setMetricName(metricName);
        
        Object paramsObj = msg.get("params");
        shellMsg.setMetricParams(paramsObj);

        if (command.equals("log")) {
            Object logLevelObj = msg.get("level");
            if (logLevelObj != null && logLevelObj instanceof Long) {
                long logLevel = (Long)logLevelObj;
                shellMsg.setLogLevel((int)logLevel);
            }
        }

        return shellMsg;
    }

    private Object readMessage() throws IOException, NoOutputException {
        try {
            return JSONValue.parseWithException(readString());
        } catch (ParseException e) {
            throw new IOException(e);
        }
    }

    private String readString() throws IOException, NoOutputException {
        StringBuilder line = new StringBuilder();

        while (true) {
            String subline = processOut.readLine();
            if (subline == null) {
                StringBuilder errorMessage = new StringBuilder();
                errorMessage.append("Pipe to subprocess seems to be broken!");
                if (line.length() == 0) {
                    errorMessage.append(" No output read.\n");
                } else {
                    errorMessage.append(" Currently read output: "
                            + line.toString() + "\n");
                }
                errorMessage.append("Serializer Exception:\n");
                throw new NoOutputException(errorMessage.toString());
            }
            if (subline.equals("end")) {
                break;
            }
            if (line.length() != 0) {
                line.append("\n");
            }
            line.append(subline);
        }
        return line.toString();
    }
}