org.openhealthtools.openatna.syslog.GenericMessageFactory.java Source code

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Here is the source code for org.openhealthtools.openatna.syslog.GenericMessageFactory.java

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/**
 *  Copyright (c) 2009-2011 University of Cardiff and others
 *
 *  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.
 *
 *  Contributors:
 *    University of Cardiff - initial API and implementation
 *    -
 */

package org.openhealthtools.openatna.syslog;

import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.openhealthtools.openatna.syslog.bsd.BsdMessageFactory;
import org.openhealthtools.openatna.syslog.protocol.ProtocolMessageFactory;

/**
 * Determies whether the message is BSD or RFC 5424 based on the first few bytes
 * of the message, and calls the appropriate MessageFactory.
 *
 * @author Andrew Harrison
 * @version $Revision:$
 * @created Aug 19, 2009: 11:48:37 AM
 * @date $Date:$ modified by $Author:$
 */

public class GenericMessageFactory extends SyslogMessageFactory {

    static Log log = LogFactory.getLog("org.openhealthtools.openatna.syslog.GenericMessageFactory");

    private static BsdMessageFactory bsdFactory = new BsdMessageFactory();
    private static ProtocolMessageFactory protFactory = new ProtocolMessageFactory();

    /**
     * returns true if this is a BSD syslog message.
     * Relies on the 5424 VERSION value being '1'
     * otherwise false
     *
     * @param bytes
     * @return
     * @throws org.openhealthtools.openatna.syslog.SyslogException
     *
     */
    private boolean isBSD(byte[] bytes) throws SyslogException {
        try {
            boolean isBSD = true;
            String s = new String(bytes);
            int close = s.indexOf('>');
            if (close > 1 && close < bytes.length - 2) {
                char next = s.charAt(close + 1);
                if (next == Constants.VERSION) {
                    next = s.charAt(close + 2);
                    if (next == ' ') {
                        isBSD = false;
                    }
                }
            }
            return isBSD;
        } catch (Exception e) {
            throw new SyslogException(e);
        }
    }

    public SyslogMessage read(InputStream in) throws SyslogException {
        try {
            PushbackInputStream pin = new PushbackInputStream(in, 7);
            byte[] bytes = new byte[7];
            pin.read(bytes);

            boolean bsd = isBSD(bytes);
            pin.unread(bytes);
            if (bsd) {
                log.debug("message is BSD style");
                return bsdFactory.read(pin);
            } else {
                log.debug("message RFC 5424");
                return protFactory.read(pin);
            }
        } catch (IOException e) {
            throw new SyslogException(e);
        }
    }
}