ymanv.forex.websocket.RatesWebSocketHandler.java Source code

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Here is the source code for ymanv.forex.websocket.RatesWebSocketHandler.java

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/**
 * Copyright (C) 2015 https://github.com/ymanv
 *
 * This software is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package ymanv.forex.websocket;

import java.io.IOException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;

import javax.annotation.PostConstruct;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.eventbus.EventBus;
import com.google.common.eventbus.Subscribe;

import ymanv.forex.event.RatesUpdatedEvent;
import ymanv.forex.model.entity.rate.RateEntity;

/**
 * http://docs.spring.io/spring/docs/current/spring-framework-reference/html/
 * websocket.html
 */
@Component
public class RatesWebSocketHandler extends TextWebSocketHandler {

    private static final Logger LOG = LoggerFactory.getLogger(RatesWebSocketHandler.class);

    @Autowired
    private ObjectMapper mapper;

    private final Set<WebSocketSession> sessions = new HashSet<>();

    @Autowired
    private EventBus bus;

    @PostConstruct
    private void registerToBus() {
        bus.register(this);
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session) {
        LOG.debug("Opened new {} in instance {}", session.getClass().getSimpleName(), session.getRemoteAddress());
        sessions.add(session);
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) {
        LOG.debug("Closed {} in instance {}", session.getClass().getSimpleName(), session.getRemoteAddress());
        sessions.remove(session);
    }

    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) throws IOException {
        session.close(CloseStatus.SERVER_ERROR);
    }

    @Subscribe
    public void send(RatesUpdatedEvent event) throws IOException {
        if (sessions.isEmpty()) {
            return;
        }

        String txt = serializeRates(event.getRates());

        for (WebSocketSession wss : new CopyOnWriteArrayList<>(sessions)) {
            wss.sendMessage(new TextMessage(txt));
        }
    }

    @VisibleForTesting
    protected String serializeRates(List<? extends RateEntity> list) throws JsonProcessingException {
        return mapper.writeValueAsString(list);
    }
}