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.

Author:

Filip Hanik

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 ChannelCoordinator coordinator

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

interceptors

protected ChannelInterceptor interceptors

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

membershipListeners

protected java.util.ArrayList membershipListeners

A list of membership listeners that subscribe to membership announcements

channelListeners

protected java.util.ArrayList 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

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.

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,
                     java.io.Serializable msg,
                     int options)
              throws ChannelException

Send a message to the destinations specified

Specified by:

send in interface Channel

Parameters:

destination - Member[] - destination.length > 1

msg - Serializable - the message to send

options - int - 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,
                     java.io.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 > 1

msg - Serializable - the message to send

options - int - 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

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

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

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

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 java.util.Iterator 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 invokations of Channel.heartbeat()

Returns:

long