de.hofuniversity.iisys.neo4j.websock.query.encoding.StringTransferUtil.java Source code

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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 de.hofuniversity.iisys.neo4j.websock.query.encoding;

import javax.websocket.MessageHandler;
import javax.websocket.RemoteEndpoint.Basic;

import org.json.JSONObject;

import de.hofuniversity.iisys.neo4j.websock.query.IMessageHandler;
import de.hofuniversity.iisys.neo4j.websock.query.WebsockQuery;
import de.hofuniversity.iisys.neo4j.websock.util.JsonConverter;

/**
 * Utility receiving text data and forwarding it to a message handler and
 * encoding and sending messages using the configured format.
 */
public class StringTransferUtil implements MessageHandler.Whole<String>, Cloneable {
    private final Basic fRemote;
    private final IMessageHandler fHandler;

    /**
     * Creates a text transfer utility, sending data over the given basic
     * remote, forwarding incoming text data to the given message handler.
     *
     * @param remote remote to send data with
     * @param handler handler to forward incoming data to
     */
    public StringTransferUtil(Basic remote, IMessageHandler handler) {
        if (remote == null) {
            throw new NullPointerException("websocket remote was null");
        }
        if (handler == null) {
            throw new NullPointerException("query handler was null");
        }

        fRemote = remote;
        fHandler = handler;
    }

    @Override
    public void onMessage(final String message) {
        fHandler.onMessage(message);
    }

    /**
     * Converts text data into a WebsockQuery. First, the converter for the
     * configured format is used, then all others are tried. If all converters
     * fail, a RuntimeException is thrown.
     *
     * @param message text data to convert
     * @return converted WebsockQuery
     */
    public WebsockQuery convert(final String message) throws Exception {
        //currently, only uncompressed JSON is supported
        JSONObject json = new JSONObject(message);
        WebsockQuery query = JsonConverter.fromJson(json);

        return query;
    }

    /**
     * Converts a WebsockQuery to the configured format and sends it.
     *
     * @param message message to send
     * @throws Exception if conversion or sending fail
     */
    public void sendMessage(final WebsockQuery message) throws Exception {
        JSONObject json = JsonConverter.toJson(message);
        fRemote.sendText(json.toString());
    }

    /**
     * Sets the format to send messages in and the primary format to try
     * decoding incoming messages with.
     * Unknown formats are ignored and logged.
     *
     * @param format encoding to use for messages (bson/json)
     * @param compression which type of compression to use
     */
    public void setFormat(String format, String compression) {
        //currently, only uncompressed JSON is supported
    }

    /**
     * @return independent transfer utility using the same connection and
     *  current configuration
     */
    public StringTransferUtil clone() {
        return new StringTransferUtil(fRemote, fHandler);
    }
}