Package org.apache.catalina.tribes.group.interceptors

Class OrderInterceptor

java.lang.Object

org.apache.catalina.tribes.group.ChannelInterceptorBase

org.apache.catalina.tribes.group.interceptors.OrderInterceptor

All Implemented Interfaces:

ChannelInterceptor, Heartbeat, MembershipListener

public class OrderInterceptor
extends ChannelInterceptorBase

The order interceptor guarantees that messages are received in the same order they were sent. This interceptor works best with the ack=true setting.
There is no point in using this with the replicationMode="fastasynchqueue" as this mode guarantees ordering.
If you are using the mode ack=false replicationMode=pooled, and have a lot of concurrent threads, this interceptor can really slow you down, as many messages will be completely out of order and the queue might become rather large. If this is the case, then you might want to set the value OrderInterceptor.maxQueue = 25 (meaning that we will never keep more than 25 messages in our queue)
Configuration Options
OrderInterceptor.expire=<milliseconds> - if a message arrives out of order, how long before we act on it default=3000ms
OrderInterceptor.maxQueue=<max queue size> - how much can the queue grow to ensure ordering. This setting is useful to avoid OutOfMemoryErrorsdefault=Integer.MAX_VALUE
OrderInterceptor.forwardExpired=<boolean> - this flag tells the interceptor what to do when a message has expired or the queue has grown larger than the maxQueue value. true means that the message is sent up the stack to the receiver that will receive and out of order message false means, forget the message and reset the message counter. default=true

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	OrderInterceptor.Counter
protected static class	OrderInterceptor.MessageOrder

Nested classes/interfaces inherited from interface org.apache.catalina.tribes.ChannelInterceptor

ChannelInterceptor.InterceptorEvent

Field Summary

Fields

Modifier and Type	Field	Description
protected static final StringManager	sm

Fields inherited from class org.apache.catalina.tribes.group.ChannelInterceptorBase

optionFlag

Constructor Summary

Constructors

Constructor	Description
OrderInterceptor()

Method Summary

Modifier and Type	Method	Description
long	getExpire()
boolean	getForwardExpired()
protected OrderInterceptor.Counter	getInCounter(Member mbr)
int	getMaxQueue()
protected OrderInterceptor.Counter	getOutCounter(Member mbr)
protected int	incCounter(Member mbr)
void	memberAdded(Member member)	A member was added to the group
void	memberDisappeared(Member member)	A member was removed from the group If the member left voluntarily, the Member.getCommand will contain the Member.SHUTDOWN_PAYLOAD data
void	messageReceived(ChannelMessage msg)	the messageReceived is invoked when a message is received.
protected boolean	processIncoming(OrderInterceptor.MessageOrder order)
protected void	processLeftOvers(Member member, boolean force)
void	sendMessage(Member[] destination, ChannelMessage msg, InterceptorPayload payload)	The sendMessage method is called when a message is being sent to one more destinations.
void	setExpire(long expire)
void	setForwardExpired(boolean forwardExpired)
void	setMaxQueue(int maxQueue)

Methods inherited from class org.apache.catalina.tribes.group.ChannelInterceptorBase

fireInterceptorEvent, getChannel, getLocalMember, getMember, getMembers, getNext, getOptionFlag, getPrevious, hasMembers, heartbeat, okToProcess, setChannel, setNext, setOptionFlag, setPrevious, start, stop

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

sm

protected static final StringManager sm

Constructor Details

OrderInterceptor

public OrderInterceptor()

Method Details

sendMessage

public void sendMessage(Member[] destination,
 ChannelMessage msg,
 InterceptorPayload payload)
                 throws ChannelException

Description copied from interface: ChannelInterceptor

The sendMessage method is called when a message is being sent to one more destinations. The interceptor can modify any of the parameters and then pass on the message down the stack by invoking getNext().sendMessage(destination,msg,payload)
Alternatively the interceptor can stop the message from being sent by not invoking getNext().sendMessage(destination,msg,payload)
If the message is to be sent asynchronous the application can be notified of completion and errors by passing in an error handler attached to a payload object.
The ChannelMessage.getAddress contains Channel.getLocalMember, and can be overwritten to simulate a message sent from another node.

Specified by:

sendMessage in interface ChannelInterceptor

Overrides:

sendMessage in class ChannelInterceptorBase

Parameters:

destination - Member[] - the destination for this message

msg - ChannelMessage - the message to be sent

payload - InterceptorPayload - the payload, carrying an error handler and future useful data, can be null

Throws:

ChannelException - if a serialization error happens.

See Also:

• ErrorHandler
• InterceptorPayload

messageReceived

public void messageReceived(ChannelMessage msg)

Description copied from interface: ChannelInterceptor

the messageReceived is invoked when a message is received. ChannelMessage.getAddress() is the sender, or the reply-to address if it has been overwritten.

Specified by:

messageReceived in interface ChannelInterceptor

Overrides:

messageReceived in class ChannelInterceptorBase

Parameters:

msg - ChannelMessage

processLeftOvers

protected void processLeftOvers(Member member,
 boolean force)

processIncoming

protected boolean processIncoming(OrderInterceptor.MessageOrder order)

Parameters:

order - MessageOrder

Returns:

boolean - true if a message expired and was processed

memberAdded

public void memberAdded(Member member)

Description copied from interface: MembershipListener

A member was added to the group

Specified by:

memberAdded in interface MembershipListener

Overrides:

memberAdded in class ChannelInterceptorBase

Parameters:

member - Member - the member that was added

memberDisappeared

public void memberDisappeared(Member member)

Description copied from interface: MembershipListener

A member was removed from the group
If the member left voluntarily, the Member.getCommand will contain the Member.SHUTDOWN_PAYLOAD data

Specified by:

memberDisappeared in interface MembershipListener

Overrides:

memberDisappeared in class ChannelInterceptorBase

Parameters:

member - Member

See Also:

• Member.SHUTDOWN_PAYLOAD

incCounter

protected int incCounter(Member mbr)

getInCounter

protected OrderInterceptor.Counter getInCounter(Member mbr)

getOutCounter

protected OrderInterceptor.Counter getOutCounter(Member mbr)

setExpire

public void setExpire(long expire)

setForwardExpired

public void setForwardExpired(boolean forwardExpired)

setMaxQueue

public void setMaxQueue(int maxQueue)

getExpire

public long getExpire()

getForwardExpired

public boolean getForwardExpired()

getMaxQueue

public int getMaxQueue()