org.apache.catalina.tribes.group

Class GroupChannel

java.lang.Object

org.apache.catalina.tribes.group.ChannelInterceptorBase

org.apache.catalina.tribes.group.GroupChannel

All Implemented Interfaces:

Channel, ChannelInterceptor, Heartbeat, ManagedChannel, MembershipListener

public class GroupChannel
extends ChannelInterceptorBase
implements ManagedChannel

The default implementation of a Channel.
The GroupChannel manages the replication channel. It coordinates message being sent and received with membership announcements. The channel has an chain of interceptors that can modify the message or perform other logic.
It manages a complete group, both membership and replication.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GroupChannel.HeartbeatThread Title: Internal heartbeat thread Description: if Channel.getHeartbeat()==true then a thread of this class is created
static class	GroupChannel.InterceptorIterator Title: Interceptor Iterator Description: An iterator to loop through the interceptors in a channel

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

ChannelInterceptor.InterceptorEvent

Field Summary

Fields

Modifier and Type	Field and Description
protected List<ChannelListener>	channelListeners A list of channel listeners that subscribe to incoming messages
protected ChannelCoordinator	coordinator The ChannelCoordinator coordinates the bottom layer components: - MembershipService - ChannelSender - ChannelReceiver
protected GroupChannel.HeartbeatThread	hbthread Internal heartbeat thread
protected boolean	heartbeat Flag to determine if the channel manages its own heartbeat If set to true, the channel will start a local thread for the heart beat.
protected long	heartbeatSleeptime If heartbeat == true then how often do we want this heartbeat to run. default is one minute
protected ChannelInterceptor	interceptors The first interceptor in the interceptor stack.
protected List<MembershipListener>	membershipListeners A list of membership listeners that subscribe to membership announcements
protected String	name the name of this channel.
protected boolean	optionCheck If set to true, the GroupChannel will check to make sure that
protected static StringManager	sm

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

optionFlag

Fields inherited from interface org.apache.catalina.tribes.Channel

DEFAULT, MBR_RX_SEQ, MBR_TX_SEQ, SEND_OPTIONS_ASYNCHRONOUS, SEND_OPTIONS_BYTE_MESSAGE, SEND_OPTIONS_DEFAULT, SEND_OPTIONS_MULTICAST, SEND_OPTIONS_SECURE, SEND_OPTIONS_SYNCHRONIZED_ACK, SEND_OPTIONS_UDP, SEND_OPTIONS_USE_ACK, SND_RX_SEQ, SND_TX_SEQ

Constructor Summary

Constructors

Constructor and Description
GroupChannel() Creates a GroupChannel.

Method Summary

Modifier and Type	Method and Description
void	addChannelListener(ChannelListener channelListener) Adds a channel listener to the channel.
void	addInterceptor(ChannelInterceptor interceptor) Adds an interceptor to the stack for message processing Interceptors are ordered in the way they are added.
void	addMembershipListener(MembershipListener membershipListener) Adds a membership listener to the channel.
protected void	checkOptionFlags() Validates the option flags that each interceptor is using and reports an error if two interceptor share the same flag.
ChannelReceiver	getChannelReceiver() Returns the channel receiver component
ChannelSender	getChannelSender() Returns the channel sender component
ChannelInterceptor	getFirstInterceptor() Returns the first interceptor of the stack.
boolean	getHeartbeat()
long	getHeartbeatSleeptime() Returns the sleep time in milliseconds that the internal heartbeat will sleep in between invocations of Channel.heartbeat()
Iterator<ChannelInterceptor>	getInterceptors() Returns an iterator of all the interceptors in this stack
MembershipService	getMembershipService() Returns the membership service component
String	getName() Return the name of this channel.
boolean	getOptionCheck()
void	heartbeat() Sends a heartbeat through the interceptor stack.
void	memberAdded(Member member) memberAdded gets invoked by the interceptor below the channel and the channel will broadcast it to the membership listeners
void	memberDisappeared(Member member) memberDisappeared gets invoked by the interceptor below the channel and the channel will broadcast it to the membership listeners
void	messageReceived(ChannelMessage msg) Callback from the interceptor stack.
void	removeChannelListener(ChannelListener channelListener) Removes a channel listener from the channel.
void	removeMembershipListener(MembershipListener membershipListener) Removes a membership listener from the channel.
UniqueId	send(Member[] destination, Serializable msg, int options) Send a message to the destinations specified
UniqueId	send(Member[] destination, Serializable msg, int options, ErrorHandler handler) Send a message to one or more members in the cluster
protected void	sendNoRpcChannelReply(RpcMessage msg, Member destination) Sends a NoRpcChannelReply message to a member This method gets invoked by the channel if a RPC message comes in and no channel listener accepts the message.
void	setChannelReceiver(ChannelReceiver clusterReceiver) Sets the channel receiver component
void	setChannelSender(ChannelSender clusterSender) Sets the channel sender component
void	setHeartbeat(boolean heartbeat) Enables or disables local heartbeat.
void	setHeartbeatSleeptime(long heartbeatSleeptime) Configure local heartbeat sleep time Only used when getHeartbeat()==true
void	setMembershipService(MembershipService membershipService) Sets the membership component
void	setName(String name) Set the name of this channel
void	setOptionCheck(boolean optionCheck) Enables/disables the option check Setting this to true, will make the GroupChannel perform a conflict check on the interceptors.
protected void	setupDefaultStack() Sets up the default implementation interceptor stack if no interceptors have been added
void	start(int svc) Starts the channel.
void	stop(int svc) Stops the channel.

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

fireInterceptorEvent, getChannel, getLocalMember, getMember, getMembers, getNext, getOptionFlag, getPrevious, hasMembers, okToProcess, sendMessage, setChannel, setNext, setOptionFlag, setPrevious

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.catalina.tribes.Channel

getLocalMember, getMember, getMembers, hasMembers

Field Detail

sm

protected static final StringManager sm

heartbeat

protected boolean heartbeat

Flag to determine if the channel manages its own heartbeat If set to true, the channel will start a local thread for the heart beat.

heartbeatSleeptime

protected long heartbeatSleeptime

If heartbeat == true then how often do we want this heartbeat to run. default is one minute

hbthread

protected GroupChannel.HeartbeatThread hbthread

Internal heartbeat thread

coordinator

protected final ChannelCoordinator coordinator

The ChannelCoordinator coordinates the bottom layer components:
- MembershipService
- ChannelSender
- ChannelReceiver

interceptors

protected ChannelInterceptor interceptors

The first interceptor in the interceptor stack. The interceptors are chained in a linked list, so we only need a reference to the first one

membershipListeners

protected final List<MembershipListener> membershipListeners

A list of membership listeners that subscribe to membership announcements

channelListeners

protected final List<ChannelListener> channelListeners

A list of channel listeners that subscribe to incoming messages

optionCheck

protected boolean optionCheck

If set to true, the GroupChannel will check to make sure that

name

protected String name

the name of this channel.

Constructor Detail

GroupChannel

public GroupChannel()

Creates a GroupChannel. This constructor will also add the first interceptor in the GroupChannel.
The first interceptor is always the channel itself.

Method Detail

addInterceptor

public void addInterceptor(ChannelInterceptor interceptor)

Adds an interceptor to the stack for message processing
Interceptors are ordered in the way they are added.
channel.addInterceptor(A);
channel.addInterceptor(C);
channel.addInterceptor(B);
Will result in a interceptor stack like this:
A -> C -> B
The complete stack will look like this:
Channel -> A -> C -> B -> ChannelCoordinator

Specified by:

addInterceptor in interface Channel

Parameters:

interceptor - ChannelInterceptorBase

heartbeat

public void heartbeat()

Sends a heartbeat through the interceptor stack.
Invoke this method from the application on a periodic basis if you have turned off internal heartbeats channel.setHeartbeat(false)

Specified by:

heartbeat in interface Channel

Specified by:

heartbeat in interface ChannelInterceptor

Specified by:

heartbeat in interface Heartbeat

Overrides:

heartbeat in class ChannelInterceptorBase

See Also:

Channel.setHeartbeat(boolean)

send

public UniqueId send(Member[] destination,
                     Serializable msg,
                     int options)
              throws ChannelException

Send a message to the destinations specified

Specified by:

send in interface Channel

Parameters:

destination - Member[] - destination.length > 0

msg - Serializable - the message to send

options - sender options, options can trigger guarantee levels and different interceptors to react to the message see class documentation for the Channel object.

Returns:

UniqueId - the unique Id that was assigned to this message

Throws:

ChannelException - - if an error occurs processing the message

See Also:

Channel

send

public UniqueId send(Member[] destination,
                     Serializable msg,
                     int options,
                     ErrorHandler handler)
              throws ChannelException

Description copied from interface: Channel

Send a message to one or more members in the cluster

Specified by:

send in interface Channel

Parameters:

destination - Member[] - destination.length > 0

msg - Serializable - the message to send

options - sender options, options can trigger guarantee levels and different interceptors to react to the message see class documentation for the Channel object.

handler - - callback object for error handling and completion notification, used when a message is sent asynchronously using the Channel.SEND_OPTIONS_ASYNCHRONOUS flag enabled.

Returns:

UniqueId - the unique Id that was assigned to this message

Throws:

ChannelException - - if an error occurs processing the message

See Also:

Channel

messageReceived

public void messageReceived(ChannelMessage msg)

Callback from the interceptor stack.
When a message is received from a remote node, this method will be invoked by the previous interceptor.
This method can also be used to send a message to other components within the same application, but its an extreme case, and you're probably better off doing that logic between the applications itself.

Specified by:

messageReceived in interface ChannelInterceptor

Overrides:

messageReceived in class ChannelInterceptorBase

Parameters:

msg - ChannelMessage

sendNoRpcChannelReply

protected void sendNoRpcChannelReply(RpcMessage msg,
                                     Member destination)

Sends a NoRpcChannelReply message to a member
This method gets invoked by the channel if a RPC message comes in and no channel listener accepts the message. This avoids timeout

Parameters:

msg - RpcMessage

destination - Member - the destination for the reply

memberAdded

public void memberAdded(Member member)

memberAdded gets invoked by the interceptor below the channel and the channel will broadcast it to the membership listeners

Specified by:

memberAdded in interface MembershipListener

Overrides:

memberAdded in class ChannelInterceptorBase

Parameters:

member - Member - the new member

memberDisappeared

public void memberDisappeared(Member member)

memberDisappeared gets invoked by the interceptor below the channel and the channel will broadcast it to the membership listeners

Specified by:

memberDisappeared in interface MembershipListener

Overrides:

memberDisappeared in class ChannelInterceptorBase

Parameters:

member - Member - the member that left or crashed

See Also:

Member.SHUTDOWN_PAYLOAD

setupDefaultStack

protected void setupDefaultStack()
                          throws ChannelException

Sets up the default implementation interceptor stack if no interceptors have been added

Throws:

ChannelException - Cluster error

checkOptionFlags

protected void checkOptionFlags()
                         throws ChannelException

Validates the option flags that each interceptor is using and reports an error if two interceptor share the same flag.

Throws:

ChannelException - Error with option flag

start

public void start(int svc)
           throws ChannelException

Starts the channel.

Specified by:

start in interface Channel

Specified by:

start in interface ChannelInterceptor

Overrides:

start in class ChannelInterceptorBase

Parameters:

svc - int - what service to start

Throws:

ChannelException - Start error

See Also:

Channel.start(int)

stop

public void stop(int svc)
          throws ChannelException

Stops the channel.

Specified by:

stop in interface Channel

Specified by:

stop in interface ChannelInterceptor

Overrides:

stop in class ChannelInterceptorBase

Parameters:

svc - int

Throws:

ChannelException - Stop error

See Also:

Channel.stop(int)

getFirstInterceptor

public ChannelInterceptor getFirstInterceptor()

Returns the first interceptor of the stack. Useful for traversal.

Returns:

ChannelInterceptor

getChannelReceiver

public ChannelReceiver getChannelReceiver()

Returns the channel receiver component

Specified by:

getChannelReceiver in interface ManagedChannel

Returns:

ChannelReceiver

See Also:

ChannelReceiver

getChannelSender

public ChannelSender getChannelSender()

Returns the channel sender component

Specified by:

getChannelSender in interface ManagedChannel

Returns:

ChannelSender

See Also:

ChannelSender

getMembershipService

public MembershipService getMembershipService()

Returns the membership service component

Specified by:

getMembershipService in interface ManagedChannel

Returns:

MembershipService

See Also:

MembershipService

setChannelReceiver

public void setChannelReceiver(ChannelReceiver clusterReceiver)

Sets the channel receiver component

Specified by:

setChannelReceiver in interface ManagedChannel

Parameters:

clusterReceiver - ChannelReceiver

See Also:

ChannelReceiver

setChannelSender

public void setChannelSender(ChannelSender clusterSender)

Sets the channel sender component

Specified by:

setChannelSender in interface ManagedChannel

Parameters:

clusterSender - ChannelSender

See Also:

ChannelSender

setMembershipService

public void setMembershipService(MembershipService membershipService)

Sets the membership component

Specified by:

setMembershipService in interface ManagedChannel

Parameters:

membershipService - MembershipService

See Also:

MembershipService

addMembershipListener

public void addMembershipListener(MembershipListener membershipListener)

Adds a membership listener to the channel.
Membership listeners are uniquely identified using the equals(Object) method

Specified by:

addMembershipListener in interface Channel

Parameters:

membershipListener - MembershipListener

See Also:

MembershipListener

removeMembershipListener

public void removeMembershipListener(MembershipListener membershipListener)

Removes a membership listener from the channel.
Membership listeners are uniquely identified using the equals(Object) method

Specified by:

removeMembershipListener in interface Channel

Parameters:

membershipListener - MembershipListener

See Also:

MembershipListener

addChannelListener

public void addChannelListener(ChannelListener channelListener)

Adds a channel listener to the channel.
Channel listeners are uniquely identified using the equals(Object) method

Specified by:

addChannelListener in interface Channel

Parameters:

channelListener - ChannelListener

See Also:

ChannelListener, Heartbeat

removeChannelListener

public void removeChannelListener(ChannelListener channelListener)

Removes a channel listener from the channel.
Channel listeners are uniquely identified using the equals(Object) method

Specified by:

removeChannelListener in interface Channel

Parameters:

channelListener - ChannelListener

See Also:

ChannelListener

getInterceptors

public Iterator<ChannelInterceptor> getInterceptors()

Returns an iterator of all the interceptors in this stack

Specified by:

getInterceptors in interface ManagedChannel

Returns:

Iterator

See Also:

Channel.addInterceptor(ChannelInterceptor)

setOptionCheck

public void setOptionCheck(boolean optionCheck)

Enables/disables the option check
Setting this to true, will make the GroupChannel perform a conflict check on the interceptors. If two interceptors are using the same option flag and throw an error upon start.

Parameters:

optionCheck - boolean

setHeartbeatSleeptime

public void setHeartbeatSleeptime(long heartbeatSleeptime)

Configure local heartbeat sleep time
Only used when getHeartbeat()==true

Parameters:

heartbeatSleeptime - long - time in milliseconds to sleep between heartbeats

setHeartbeat

public void setHeartbeat(boolean heartbeat)

Enables or disables local heartbeat. if setHeartbeat(true) is invoked then the channel will start an internal thread to invoke Channel.heartbeat() every getHeartbeatSleeptime milliseconds

Specified by:

setHeartbeat in interface Channel

Parameters:

heartbeat - boolean

See Also:

Channel.heartbeat()

getOptionCheck

public boolean getOptionCheck()

Returns:

boolean

See Also:

setOptionCheck(boolean)

getHeartbeat

public boolean getHeartbeat()

Returns:

boolean

See Also:

setHeartbeat(boolean)

getHeartbeatSleeptime

public long getHeartbeatSleeptime()

Returns the sleep time in milliseconds that the internal heartbeat will sleep in between invocations of Channel.heartbeat()

Returns:

long

getName

public String getName()

Description copied from interface: Channel

Return the name of this channel.

Specified by:

getName in interface Channel

Returns:

channel name

setName

public void setName(String name)

Description copied from interface: Channel

Set the name of this channel

Specified by:

setName in interface Channel

Parameters:

name - The new channel name