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/** Notice of modification as required by the LGPL
* This file was modified by Gemstone Systems Inc. on
* $Date$
**/
// $Id: TOTAL.java,v 1.11 2005/08/08 12:45:44 belaban Exp $
package com.gemstone.org.jgroups.protocols;
import com.gemstone.org.jgroups.oswego.concurrent.ReadWriteLock;
import com.gemstone.org.jgroups.oswego.concurrent.WriterPreferenceReadWriteLock;
import com.gemstone.org.jgroups.Address;
import com.gemstone.org.jgroups.Event;
import com.gemstone.org.jgroups.Message;
import com.gemstone.org.jgroups.View;
import com.gemstone.org.jgroups.stack.AckSenderWindow;
import com.gemstone.org.jgroups.stack.Protocol;
import com.gemstone.org.jgroups.util.ExternalStrings;
import com.gemstone.org.jgroups.util.TimeScheduler;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.*;
/**
* Implements the total ordering layer using a message sequencer
*
*
* The protocol guarantees that all bcast sent messages will be delivered in
* the same order to all members. For that it uses a sequencer which assignes
* monotonically increasing sequence ID to broadcasts. Then all group members
* deliver the bcasts in ascending sequence ID order.
*
*
* -
* When a bcast message comes down to this layer, it is placed in the pending
* down queue. A bcast request is sent to the sequencer.
* -
* When the sequencer receives a bcast request, it creates a bcast reply
* message and assigns to it a monotonically increasing seqID and sends it back
* to the source of the bcast request.
* -
* When a broadcast reply is received, the corresponding bcast message is
* assigned the received seqID. Then it is broadcasted.
* -
* Received bcasts are placed in the up queue. The queue is sorted according
* to the seqID of the bcast. Any message at the head of the up queue with a
* seqID equal to the next expected seqID is delivered to the layer above.
* -
* Unicast messages coming from the layer below are forwarded above.
* -
* Unicast messages coming from the layer above are forwarded below.
*
*
* Please note that once a BLOCK_OK is acknowledged messages
* coming from above are discarded! Either the application must stop
* sending messages when a BLOCK event is received from the
* channel or a QUEUE layer should be placed above this one. Received messages
* are still delivered above though.
*
* bcast requests are retransmitted periodically until a bcast reply is
* received. In case a BCAST_REP is on its way during a BCAST_REQ
* retransmission, then the next BCAST_REP will be to a non-existing
* BCAST_REQ. So, a nulll BCAST message is sent to fill the created gap in
* the seqID of all members.
*
* @author [email protected]
*/
public class TOTAL extends Protocol {
/**
* The header processed by the TOTAL layer and intended for TOTAL
* inter-stack communication
*/
public static class Header extends com.gemstone.org.jgroups.Header {
// Header types
/**
* Null value for the tag
*/
public static final int NULL_TYPE=-1;
/**
* Request to broadcast by the source
*/
public static final int REQ=0;
/**
* Reply to broadcast request.
*/
public static final int REP=1;
/**
* Unicast message
*/
public static final int UCAST=2;
/**
* Broadcast Message
*/
public static final int BCAST=3;
/**
* The header's type tag
*/
public int type;
/**
* The ID used by the message source to match replies from the
* sequencer
*/
public long localSequenceID;
/**
* The ID imposing the total order of messages
*/
public long sequenceID;
/**
* used for externalization
*/
public Header() {
}
/**
* Create a header for the TOTAL layer
*
* @param type the header's type
* @param localSeqID the ID used by the sender of broadcasts to match
* requests with replies from the sequencer
* @param seqID the ID imposing the total order of messages
* @throws IllegalArgumentException if the provided header type is
* unknown
*/
public Header(int type, long localSeqID, long seqID) {
super();
switch(type) {
case REQ:
case REP:
case UCAST:
case BCAST:
this.type=type;
break;
default:
this.type=NULL_TYPE;
throw new IllegalArgumentException("type");
}
this.localSequenceID=localSeqID;
this.sequenceID=seqID;
}
/**
* For debugging purposes
*/
@Override // GemStoneAddition
public String toString() {
StringBuffer buffer=new StringBuffer();
String typeName;
buffer.append("[TOTAL.Header");
switch(type) {
case REQ:
typeName="REQ";
break;
case REP:
typeName="REP";
break;
case UCAST:
typeName="UCAST";
break;
case BCAST:
typeName="BCAST";
break;
case NULL_TYPE:
typeName="NULL_TYPE";
break;
default:
typeName="";
break;
}
buffer.append(", type=" + typeName);
buffer.append(", " + "localID=" + localSequenceID);
buffer.append(", " + "seqID=" + sequenceID);
buffer.append(']');
return (buffer.toString());
}
/**
* Manual serialization
*/
public void writeExternal(ObjectOutput out) throws IOException {
out.writeInt(type);
out.writeLong(localSequenceID);
out.writeLong(sequenceID);
}
/**
* Manual deserialization
*/
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
type=in.readInt();
localSequenceID=in.readLong();
sequenceID=in.readLong();
}
}
/**
* The retransmission listener - It is called by the
* AckSenderWindow when a retransmission should occur
*/
private class Command implements AckSenderWindow.RetransmitCommand {
Command() {
}
public void retransmit(long seqNo, Message msg) {
_retransmitBcastRequest(seqNo);
}
// GemstoneAddition
public long getMaxRetransmissionBurst() {
return 0;
}
}
/**
* Protocol name
*/
private static final String PROT_NAME="TOTAL";
/**
* Property names
*/
private static final String TRACE_PROP="trace";
/**
* Average time between broadcast request retransmissions
*/
private final long[] AVG_RETRANSMIT_INTERVAL=new long[]{1000, 2000, 3000, 4000};
/**
* Null value for the IDs
*/
private static final long NULL_ID=-1;
// Layer sending states
/**
* No group has been joined yet
*/
private static final int NULL_STATE=-1;
/**
* When set, all messages are sent/received
*/
private static final int RUN=0;
/**
* When set, only session-specific messages are sent/received, i.e. only
* messages essential to the session's integrity
*/
private static final int FLUSH=1;
/**
* No message is sent to the layer below
*/
private static final int BLOCK=2;
/**
* The state lock allowing multiple reads or a single write
*/
private final ReadWriteLock stateLock=new WriterPreferenceReadWriteLock();
/**
* Protocol layer message-sending state
*/
private int state=NULL_STATE;
/**
* The address of this stack
*/
private Address addr=null;
/**
* The address of the sequencer
*/
private Address sequencerAddr=null;
/**
* The sequencer's seq ID. The ID of the most recently broadcast reply
* message
*/
private long sequencerSeqID=NULL_ID;
/**
* The local sequence ID, i.e. the ID sent with the last broadcast request
* message. This is increased with every broadcast request sent to the
* sequencer and it's used to match the requests with the sequencer's
* replies
*/
private long localSeqID=NULL_ID;
/**
* The total order sequence ID. This is the ID of the most recently
* delivered broadcast message. As the sequence IDs are increasing without
* gaps, this is used to detect missing broadcast messages
*/
private long seqID=NULL_ID;
/**
* The list of unanswered broadcast requests to the sequencer. The entries
* are stored in increasing local sequence ID, i.e. in the order they were
*
* sent localSeqID -> Broadcast msg to be sent.
*/
private SortedMap reqTbl;
/**
* The list of received broadcast messages that haven't yet been delivered
* to the layer above. The entries are stored in increasing sequence ID,
* i.e. in the order they must be delivered above
*
* seqID -> Received broadcast msg
*/
private SortedMap upTbl;
/**
* Retranmitter for pending broadcast requests
*/
private AckSenderWindow retransmitter;
/**
* Print addresses in host_ip:port form to bypass DNS
*/
private String _addrToString(Object addr) {
return (
addr == null ? "" :
((addr instanceof com.gemstone.org.jgroups.stack.IpAddress) ?
(((com.gemstone.org.jgroups.stack.IpAddress)addr).getIpAddress(
).getHostAddress() + ':' +
((com.gemstone.org.jgroups.stack.IpAddress)addr).getPort()) :
addr.toString())
);
}
/**
* @return this protocol's name
*/
private String _getName() {
return (PROT_NAME);
}
/**
* Configure the protocol based on the given list of properties
*
* @param properties the list of properties to use to setup this layer
* @return false if there was any unrecognized property or a property with
* an invalid value
*/
private boolean _setProperties(Properties properties) {
String value;
// trace
// Parse & remove property but ignore it; use Trace.trace instead
value=properties.getProperty(TRACE_PROP);
if(value != null) properties.remove(TRACE_PROP);
if(properties.size() > 0) {
if(log.isErrorEnabled())
log.error("The following properties are not " +
"recognized: " + properties.toString());
return (false);
}
return (true);
}
/**
* Events that some layer below must handle
*
* @return the set of Events that must be handled by some layer
* below
*/
Vector _requiredDownServices() {
Vector services=new Vector();
return (services);
}
/**
* Events that some layer above must handle
*
* @return the set of Events that must be handled by some
* layer above
*/
Vector _requiredUpServices() {
Vector services=new Vector();
return (services);
}
/**
* Extract as many messages as possible from the pending up queue and send
* them to the layer above
*/
private void _deliverBcast() {
Message msg;
Header header;
synchronized(upTbl) {
while((msg=(Message)upTbl.remove(Long.valueOf(seqID + 1))) != null) {
header=(Header)msg.removeHeader(getName());
if(header.localSequenceID != NULL_ID) passUp(new Event(Event.MSG, msg));
++seqID;
}
} // synchronized(upTbl)
}
/**
* Add all undelivered bcasts sent by this member in the req queue and then
* replay this queue
*/
private void _replayBcast() {
Iterator it;
Message msg;
Header header;
// i. Remove all undelivered bcasts sent by this member and place them
// again in the pending bcast req queue
synchronized(upTbl) {
if(upTbl.size() > 0)
if(log.isInfoEnabled()) log.info(ExternalStrings.TOTAL_REPLAYING_UNDELIVERED_BCASTS);
it=upTbl.entrySet().iterator();
while(it.hasNext()) {
msg=(Message)((Map.Entry)it.next()).getValue();
it.remove();
if(!msg.getSrc().equals(addr)) {
if(log.isInfoEnabled())
log.info("During replay: " +
"discarding BCAST[" +
((TOTAL.Header)msg.getHeader(getName())).sequenceID +
"] from " + _addrToString(msg.getSrc()));
continue;
}
header=(Header)msg.removeHeader(getName());
if(header.localSequenceID == NULL_ID) continue;
_sendBcastRequest(msg, header.localSequenceID);
}
} // synchronized(upTbl)
}
/**
* Send a unicast message: Add a UCAST header
*
* @param msg the message to unicast
* @return the message to send
*/
private Message _sendUcast(Message msg) {
msg.putHeader(getName(), new Header(Header.UCAST, NULL_ID, NULL_ID));
return (msg);
}
/**
* Replace the original message with a broadcast request sent to the
* sequencer. The original bcast message is stored locally until a reply to
* bcast is received from the sequencer. This function has the side-effect
* of increasing the localSeqID
*
* @param msg the message to broadcast
*/
private void _sendBcastRequest(Message msg) {
_sendBcastRequest(msg, ++localSeqID);
}
/**
* Replace the original message with a broadcast request sent to the
* sequencer. The original bcast message is stored locally until a reply
* to bcast is received from the sequencer
*
* @param msg the message to broadcast
* @param id the local sequence ID to use
*/
private void _sendBcastRequest(Message msg, long id) {
// i. Store away the message while waiting for the sequencer's reply
// ii. Send a bcast request immediatelly and also schedule a
// retransmission
synchronized(reqTbl) {
reqTbl.put(Long.valueOf(id), msg);
}
_transmitBcastRequest(id);
retransmitter.add(id, msg);
}
/**
* Send the bcast request with the given localSeqID
*
* @param seqID the local sequence id of the
*/
private void _transmitBcastRequest(long seqID) {
Message reqMsg;
// i. If NULL_STATE, then ignore, just transient state before
// shutting down the retransmission thread
// ii. If blocked, be patient - reschedule
// iii. If the request is not pending any more, acknowledge it
// iv. Create a broadcast request and send it to the sequencer
if(state == NULL_STATE) {
if(log.isInfoEnabled()) log.info(ExternalStrings.TOTAL_TRANSMIT_BCAST_REQ_0__IN_NULL_STATE, seqID);
return;
}
if(state == BLOCK) return;
synchronized(reqTbl) {
if(!reqTbl.containsKey(Long.valueOf(seqID))) {
retransmitter.ack(seqID);
return;
}
}
reqMsg=new Message(sequencerAddr, addr, new byte[0]);
reqMsg.putHeader(getName(), new Header(Header.REQ, seqID, NULL_ID));
passDown(new Event(Event.MSG, reqMsg));
}
/**
* Receive a unicast message: Remove the UCAST header
*
* @param msg the received unicast message
*/
private void _recvUcast(Message msg) {
msg.removeHeader(getName());
}
/**
* Receive a broadcast message: Put it in the pending up queue and then
* try to deliver above as many messages as possible
*
* @param msg the received broadcast message
*/
private void _recvBcast(Message msg) {
Header header=(Header)msg.getHeader(getName());
// i. Put the message in the up pending queue only if it's not
// already there, as it seems that the event may be received
// multiple times before a view change when all members are
// negotiating a common set of stable msgs
//
// ii. Deliver as many messages as possible
synchronized(upTbl) {
if(header.sequenceID <= seqID)
return;
upTbl.put(Long.valueOf(header.sequenceID), msg);
}
_deliverBcast();
}
/**
* Received a bcast request - Ignore if not the sequencer, else send a
* bcast reply
*
* @param msg the broadcast request message
*/
private void _recvBcastRequest(Message msg) {
Header header;
Message repMsg;
// i. If blocked, discard the bcast request
// ii. Assign a seqID to the message and send it back to the requestor
if(!addr.equals(sequencerAddr)) {
if(log.isErrorEnabled())
log.error("Received bcast request " +
"but not a sequencer");
return;
}
if(state == BLOCK) {
if(log.isInfoEnabled()) log.info(ExternalStrings.TOTAL_BLOCKED_DISCARD_BCAST_REQ);
return;
}
header=(Header)msg.getHeader(getName());
++sequencerSeqID;
repMsg=new Message(msg.getSrc(), addr, new byte[0]);
repMsg.putHeader(getName(), new Header(Header.REP, header.localSequenceID,
sequencerSeqID));
passDown(new Event(Event.MSG, repMsg));
}
/**
* Received a bcast reply - Match with the pending bcast request and move
* the message in the list of messages to be delivered above
*
* @param header the header of the bcast reply
*/
private void _recvBcastReply(Header header) {
Message msg;
long id;
// i. If blocked, discard the bcast reply
//
// ii. Assign the received seqID to the message and broadcast it
//
// iii.
// - Acknowledge the message to the retransmitter
// - If non-existent BCAST_REQ, send a fake bcast to avoid seqID gaps
// - If localID == NULL_ID, it's a null BCAST, else normal BCAST
// - Set the seq ID of the message to the one sent by the sequencer
if(state == BLOCK) {
if(log.isInfoEnabled()) log.info(ExternalStrings.TOTAL_BLOCKED_DISCARD_BCAST_REP);
return;
}
synchronized(reqTbl) {
msg=(Message)reqTbl.remove(Long.valueOf(header.localSequenceID));
}
if(msg != null) {
retransmitter.ack(header.localSequenceID);
id=header.localSequenceID;
}
else {
if(log.isInfoEnabled())
log.info("Bcast reply to " +
"non-existent BCAST_REQ[" + header.localSequenceID +
"], Sending NULL bcast");
id=NULL_ID;
msg=new Message(null, addr, new byte[0]);
}
msg.putHeader(getName(), new Header(Header.BCAST, id, header.sequenceID));
passDown(new Event(Event.MSG, msg));
}
/**
* Resend the bcast request with the given localSeqID
*
* @param seqID the local sequence id of the
*/
protected/*GemStoneAddition*/ void _retransmitBcastRequest(long seqID) {
// *** Get a shared lock
try {
stateLock.readLock().acquire();
try {
if(log.isInfoEnabled()) log.info(ExternalStrings.TOTAL_RETRANSMIT_BCAST_REQ_0, seqID);
_transmitBcastRequest(seqID);
}
finally {
stateLock.readLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
log.error(ExternalStrings.TOTAL_FAILED_ACQUIRING_A_READ_LOCK, e);
}
}
/* Up event handlers
* If the return value is true the event travels further up the stack
* else it won't be forwarded
*/
/**
* Prepare for a VIEW_CHANGE: switch to flushing state
*
* @return true if the event is to be forwarded further up
*/
private boolean _upBlock() {
// *** Get an exclusive lock
try {
stateLock.writeLock().acquire();
try {
state=FLUSH;
// *** Revoke the exclusive lock
}
finally {
stateLock.writeLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
log.error(ExternalStrings.TOTAL_FAILED_ACQUIRING_THE_WRITE_LOCK, e);
}
return (true);
}
/**
* Handle an up MSG event
*
* @param event the MSG event
* @return true if the event is to be forwarded further up
*/
private boolean _upMsg(Event event) {
Message msg;
Object obj;
Header header;
// *** Get a shared lock
try {
stateLock.readLock().acquire();
try {
// If NULL_STATE, shouldn't receive any msg on the up queue!
if(state == NULL_STATE) {
if(log.isErrorEnabled()) log.error(ExternalStrings.TOTAL_UP_MSG_IN_NULL_STATE);
return (false);
}
// Peek the header:
//
// (UCAST) A unicast message - Send up the stack
// (BCAST) A broadcast message - Handle specially
// (REQ) A broadcast request - Handle specially
// (REP) A broadcast reply from the sequencer - Handle specially
msg=(Message)event.getArg();
if(!((obj=msg.getHeader(getName())) instanceof TOTAL.Header)) {
if(log.isErrorEnabled()) log.error(ExternalStrings.TOTAL_NO_TOTALHEADER_FOUND);
return (false);
}
header=(Header)obj;
switch(header.type) {
case Header.UCAST:
_recvUcast(msg);
return (true);
case Header.BCAST:
_recvBcast(msg);
return (false);
case Header.REQ:
_recvBcastRequest(msg);
return (false);
case Header.REP:
_recvBcastReply(header);
return (false);
default:
if(log.isErrorEnabled()) log.error(ExternalStrings.TOTAL_UNKNOWN_HEADER_TYPE);
return (false);
}
// ** Revoke the shared lock
}
finally {
stateLock.readLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
if(log.isErrorEnabled()) log.error(e.getMessage());
}
return (true);
}
/**
* Set the address of this group member
*
* @param event the SET_LOCAL_ADDRESS event
* @return true if event should be forwarded further up
*/
private boolean _upSetLocalAddress(Event event) {
// *** Get an exclusive lock
try {
stateLock.writeLock().acquire();
try {
addr=(Address)event.getArg();
}
finally {
stateLock.writeLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt();
log.error(e.getMessage());
}
return (true);
}
/**
* Handle view changes
*
* param event the VIEW_CHANGE event
*
* @return true if the event should be forwarded to the layer above
*/
private boolean _upViewChange(Event event) {
Object oldSequencerAddr;
// *** Get an exclusive lock
try {
stateLock.writeLock().acquire();
try {
state=RUN;
// i. See if this member is the sequencer
// ii. If this is the sequencer, reset the sequencer's sequence ID
// iii. Reset the last received sequence ID
//
// iv. Replay undelivered bcasts: Put all the undelivered bcasts
// sent by us back to the req queue and discard the rest
oldSequencerAddr=sequencerAddr;
sequencerAddr=
(Address)((View)event.getArg()).getMembers().elementAt(0);
if(addr.equals(sequencerAddr)) {
sequencerSeqID=NULL_ID;
if((oldSequencerAddr == null) ||
(!addr.equals(oldSequencerAddr)))
if(log.isInfoEnabled()) log.info(ExternalStrings.TOTAL_IM_THE_NEW_SEQUENCER);
}
seqID=NULL_ID;
_replayBcast();
// *** Revoke the exclusive lock
}
finally {
stateLock.writeLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
log.error(e.getMessage());
}
return (true);
}
/*
* Down event handlers
* If the return value is true the event travels further down the stack
* else it won't be forwarded
*/
/**
* Blocking confirmed - No messages should come from above until a
* VIEW_CHANGE event is received. Switch to blocking state.
*
* @return true if event should travel further down
*/
private boolean _downBlockOk() {
// *** Get an exclusive lock
try {
stateLock.writeLock().acquire();
try {
state=BLOCK;
}
finally {
stateLock.writeLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
log.error(e.getMessage());
}
return (true);
}
/**
* A MSG event travelling down the stack. Forward unicast messages, treat
* specially the broadcast messages.
*
* If in BLOCK state, i.e. it has replied to a
* BLOCk_OK and hasn't yet received a
* VIEW_CHANGE event, messages are discarded
*
* If in FLUSH state, forward unicast but queue broadcasts
*
* @param event the MSG event
* @return true if event should travel further down
*/
private boolean _downMsg(Event event) {
Message msg;
// *** Get a shared lock
try {
stateLock.readLock().acquire();
try {
// i. Discard all msgs, if in NULL_STATE
// ii. Discard all msgs, if blocked
if(state == NULL_STATE) {
if(log.isErrorEnabled()) log.error(ExternalStrings.TOTAL_DISCARD_MSG_IN_NULL_STATE);
return (false);
}
if(state == BLOCK) {
if(log.isErrorEnabled()) log.error(ExternalStrings.TOTAL_BLOCKED_DISCARD_MSG);
return (false);
}
msg=(Message)event.getArg();
if(msg.getDest() == null) {
_sendBcastRequest(msg);
return (false);
}
else {
msg=_sendUcast(msg);
event.setArg(msg);
}
// ** Revoke the shared lock
}
finally {
stateLock.readLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
log.error(e.getMessage());
}
return (true);
}
/**
* Prepare this layer to receive messages from above
*/
@Override // GemStoneAddition
public void start() throws Exception {
TimeScheduler timer;
timer=stack != null ? stack.timer : null;
if(timer == null)
throw new Exception("TOTAL.start(): timer is null");
reqTbl=new TreeMap();
upTbl=new TreeMap();
retransmitter=new AckSenderWindow(new Command(), AVG_RETRANSMIT_INTERVAL);
}
/**
* Handle the stop() method travelling down the stack.
*
* The local addr is set to null, since after a Start->Stop->Start
* sequence this member's addr is not guaranteed to be the same
*/
@Override // GemStoneAddition
public void stop() {
try {
stateLock.writeLock().acquire();
try {
state=NULL_STATE;
retransmitter.reset();
reqTbl.clear();
upTbl.clear();
addr=null;
}
finally {
stateLock.writeLock().release();
}
}
catch(InterruptedException e) {
Thread.currentThread().interrupt(); // GemStoneAddition
log.error(e.getMessage());
}
}
/**
* Process an event coming from the layer below
*
* @param event the event to process
*/
private void _up(Event event) {
switch(event.getType()) {
case Event.BLOCK:
if(!_upBlock()) return;
break;
case Event.MSG:
if(!_upMsg(event)) return;
break;
case Event.SET_LOCAL_ADDRESS:
if(!_upSetLocalAddress(event)) return;
break;
case Event.VIEW_CHANGE:
if(!_upViewChange(event)) return;
break;
default:
break;
}
passUp(event);
}
/**
* Process an event coming from the layer above
*
* @param event the event to process
*/
private void _down(Event event) {
switch(event.getType()) {
case Event.BLOCK_OK:
if(!_downBlockOk()) return;
break;
case Event.MSG:
if(!_downMsg(event)) return;
break;
default:
break;
}
passDown(event);
}
/**
* Create the TOTAL layer
*/
public TOTAL() {
}
// Methods deriving from Protocol
// javadoc inherited from superclass
@Override // GemStoneAddition
public String getName() {
return (_getName());
}
// javadoc inherited from superclass
@Override // GemStoneAddition
public boolean setProperties(Properties properties) {
return (_setProperties(properties));
}
// javadoc inherited from superclass
@Override // GemStoneAddition
public Vector requiredDownServices() {
return (_requiredDownServices());
}
// javadoc inherited from superclass
@Override // GemStoneAddition
public Vector requiredUpServices() {
return (_requiredUpServices());
}
// javadoc inherited from superclass
@Override // GemStoneAddition
public void up(Event event) {
_up(event);
}
// javadoc inherited from superclass
@Override // GemStoneAddition
public void down(Event event) {
_down(event);
}
}