/*******************************************************************************
* Copyright (c) 1998, 2010 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.sessions.coordination;
import org.eclipse.persistence.sessions.coordination.ServiceId;
/**
* <p>
* <b>Purpose</b>: A structured message object to announce a new RCM service
* instance becoming available
* <p>
* <b>Description</b>: This object is sent over the multicast by a service wanting
* to join the EclipseLink cluster. It is received by all other services subscribing
* to the same channel. Receipt of this announcement triggers an exchange protocol
* between the sending and receiving services to establish communications with all
* of the other services on the channel.
* <p>
*/
public class ServiceAnnouncement {
/** The id information of the sending service */
ServiceId serviceId;
/**
* INTERNAL:
* Constructor to initialize a new instance when receiving a message
*/
public ServiceAnnouncement(byte[] bytes) {
readFromBytes(bytes);
}
/**
* INTERNAL:
* Constructor to initialize a new instance when creating a message
*/
public ServiceAnnouncement(ServiceId newServiceId) {
this.serviceId = newServiceId;
}
/**
* INTERNAL:
* Initialize the instance fields from the serialized bytes.
*
* Assumptions:
* - Same character converters exist on the reading and storing sides
* - Strings are not greater than 255 bytes (bytes, not characters)
*
* Byte storage:
* - 1 byte to store length of String that is to follow
* - String of 'length' bytes follows
*/
public void readFromBytes(byte[] bytes) {
serviceId = new ServiceId();
int curPos = 0;
// Read the channel
int channelLength = bytes[curPos];
curPos++;
serviceId.setChannel(new String(bytes, curPos, channelLength));
curPos += channelLength;
// Read the id
int idLength = bytes[curPos];
curPos++;
serviceId.setId(new String(bytes, curPos, idLength));
curPos += idLength;
// Read the URL
int urlLength = bytes[curPos];
curPos++;
if (urlLength > 0) {
serviceId.setURL(new String(bytes, curPos, urlLength));
}
}
/**
* INTERNAL:
* Convert the instance attributes to serialized bytes.
*
* Assumptions:
* - Same character converters exist on the reading and storing sides
* - channel, id and converted to bytes < 256 bytes each
*
* Byte storage:
* - 1 byte to store length of String that is to follow
* - String of 'length' bytes follows
*/
public byte[] toBytes() {
byte[] bytes;
int curPos = 0;
// Convert the strings to bytes
byte[] channelBytes = serviceId.getChannel().getBytes();
int channelLength = channelBytes.length;
byte[] idBytes = serviceId.getId().getBytes();
int idLength = idBytes.length;
byte[] urlBytes = null;
int urlLength = 0;
if (serviceId.getURL() == null) {
urlBytes = new byte[]{};
} else {
urlBytes = serviceId.getURL().getBytes();
urlLength = urlBytes.length;
}
// Create the byte array to hold the data
bytes = new byte[channelLength + idLength + urlLength + 3];
// Store the fields in the byte array
bytes[curPos] = (byte)channelLength;
curPos++;
System.arraycopy(channelBytes, 0, bytes, curPos, channelLength);
curPos += channelLength;
bytes[curPos] = (byte)idLength;
curPos++;
System.arraycopy(idBytes, 0, bytes, curPos, idLength);
curPos += idLength;
bytes[curPos] = (byte)urlLength;
curPos++;
System.arraycopy(urlBytes, 0, bytes, curPos, urlLength);
return bytes;
}
/**
* INTERNAL:
* Return the id of the service sending this announcement
*/
public ServiceId getServiceId() {
return serviceId;
}
}