nats.codec.ClientFrameDecoder.java Source code

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Here is the source code for nats.codec.ClientFrameDecoder.java

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/*
 *   Copyright (c) 2013 Mike Heath.  All rights reserved.
 *
 *   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 nats.codec;

import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.regex.Pattern;

/**
 * @author Mike Heath
 */
public class ClientFrameDecoder extends AbstractFrameDecoder<ClientFrame> {

    private static final Logger LOGGER = LoggerFactory.getLogger(ClientFrameDecoder.class);

    public static final String CMD_CONNECT = "CONNECT";
    public static final String CMD_PUBLISH = "PUB";
    public static final String CMD_SUBSCRIBE = "SUB";
    public static final String CMD_UNSUBSCRIBE = "UNSUB";

    private static final Pattern PING_PATTERN = Pattern.compile("^PING", Pattern.CASE_INSENSITIVE);
    private static final Pattern PONG_PATTERN = Pattern.compile("^PONG", Pattern.CASE_INSENSITIVE);

    @Override
    protected ClientFrame decodeCommand(ChannelHandlerContext context, String command, ByteBuf in) {
        LOGGER.trace("Decoding '{}'", command);

        // CONNECT
        if (command.startsWith(CMD_CONNECT)) {
            final String body = command.substring(CMD_CONNECT.length()).trim();
            final ConnectBody connectBody = ConnectBody.parse(body);
            return new ClientConnectFrame(connectBody);
        }

        // PING
        if (PING_PATTERN.matcher(command).matches()) {
            return ClientPingFrame.PING;
        }

        // PONG
        if (PONG_PATTERN.matcher(command).matches()) {
            return ClientPongFrame.PONG;
        }

        // PUB
        if (command.startsWith(CMD_PUBLISH)) {
            try {
                final String[] parts = command.substring(CMD_PUBLISH.length()).trim().split("\\s+");
                if (parts.length < 2 || parts.length > 3) {
                    throw new NatsDecodingException(command);
                }
                final String subject = parts[0];
                final int length = Integer.parseInt(parts[parts.length - 1]);
                final String replyTo = (parts.length == 3) ? parts[1] : null;
                final ByteBuf bodyBytes = in.readBytes(length);
                in.skipBytes(ByteBufUtil.CRLF.length);
                final String body = new String(bodyBytes.array());
                return new ClientPublishFrame(subject, body, replyTo);
            } catch (NumberFormatException e) {
                throw new NatsDecodingException(command);
            }
        }

        // SUB
        if (command.startsWith(CMD_SUBSCRIBE)) {
            final String[] parts = command.substring(CMD_SUBSCRIBE.length()).trim().split("\\s+");
            if (parts.length < 2 || parts.length > 3) {
                throw new NatsDecodingException(command);
            }
            final String subject = parts[0];
            final String id = parts[parts.length - 1];
            final String queueGroup = (parts.length == 3) ? parts[1] : null;
            return new ClientSubscribeFrame(id, subject, queueGroup);
        }

        // UNSUB
        if (command.startsWith(CMD_UNSUBSCRIBE)) {
            final String[] parts = command.substring(CMD_UNSUBSCRIBE.length()).trim().split("\\s+");
            if (parts.length < 1 || parts.length > 2) {
                throw new NatsDecodingException(command);
            }
            final String id = parts[0];
            final Integer maxMessages = (parts.length == 2) ? Integer.valueOf(parts[1]) : null;
            return new ClientUnsubscribeFrame(id, maxMessages);
        }

        throw new NatsDecodingException(command);
    }

}