nats.codec.ServerFrameDecoder.java Source code

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Here is the source code for nats.codec.ServerFrameDecoder.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.Matcher;
import java.util.regex.Pattern;

/**
 * Decodes frames sent from the server.
 *
 * @author Mike Heath
 */
public class ServerFrameDecoder extends AbstractFrameDecoder<ServerFrame> {

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

    // Regular expressions used for parsing server messages
    private static final Pattern MSG_PATTERN = Pattern
            .compile("^MSG\\s+(\\S+)\\s+(\\S+)\\s+((\\S+)[^\\S\\r\\n]+)?(\\d+)", Pattern.CASE_INSENSITIVE);
    private static final Pattern OK_PATTERN = Pattern.compile("^\\+OK\\s*", Pattern.CASE_INSENSITIVE);
    private static final Pattern ERR_PATTERN = Pattern.compile("^-ERR\\s*('.+')?", Pattern.CASE_INSENSITIVE);
    private static final Pattern PING_PATTERN = Pattern.compile("^PING", Pattern.CASE_INSENSITIVE);
    private static final Pattern PONG_PATTERN = Pattern.compile("^PONG", Pattern.CASE_INSENSITIVE);
    private static final Pattern INFO_PATTERN = Pattern.compile("^INFO\\s+([^\\r\\n]+)", Pattern.CASE_INSENSITIVE);

    public ServerFrameDecoder() {
        super();
    }

    public ServerFrameDecoder(int maxMessageSize) {
        super(maxMessageSize);
    }

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

        Matcher matcher = MSG_PATTERN.matcher(command);
        if (matcher.matches()) {
            final String subject = matcher.group(1);
            final String id = matcher.group(2);
            final String replyTo = matcher.group(4);
            final int length = Integer.valueOf(matcher.group(5));
            if (length > getMaxMessageSize()) {
                throwTooLongFrameException(context);
            }
            final ByteBuf bodyBytes = in.readBytes(length);
            final String body = new String(bodyBytes.array());
            in.skipBytes(ByteBufUtil.CRLF.length);
            return new ServerPublishFrame(id, subject, replyTo, body);
        }
        matcher = INFO_PATTERN.matcher(command);
        if (matcher.matches()) {
            return new ServerInfoFrame(matcher.group(1));
        }
        matcher = OK_PATTERN.matcher(command);
        if (matcher.matches()) {
            return ServerOkFrame.OK_MESSAGE;
        }
        matcher = ERR_PATTERN.matcher(command);
        if (matcher.matches()) {
            return new ServerErrorFrame(matcher.group(1));
        }
        if (PING_PATTERN.matcher(command).matches()) {
            return ServerPingFrame.PING;
        }
        if (PONG_PATTERN.matcher(command).matches()) {
            return ServerPongFrame.PONG;
        }
        throw new NatsDecodingException(command);
    }
}