GroupChannel (Apache Tomcat 8.0.15 API Documentation)

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<Object>`	`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<Object>`	`membershipListeners` A list of membership listeners that subscribe to membership announcements
`protected boolean`	`optionCheck` If set to true, the GroupChannel will check to make sure that

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.

Constructors
Constructor and Description
`GroupChannel()` Creates a GroupChannel.

Method Summary

Methods
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
`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`	`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, getLocalMember, getMember, getMembers, getNext, getOptionFlag, getPrevious, hasMembers, okToProcess, sendMessage, 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
  - 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<Object> membershipListeners
```
    A list of membership listeners that subscribe to membership announcements
  - channelListeners
```
protected final List<Object> 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
- 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
  - 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 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

Class GroupChannel

Nested Class Summary

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

Field Summary

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

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

Constructor Summary

Method Summary

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

Methods inherited from class java.lang.Object

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

Field Detail

heartbeat

heartbeatSleeptime

hbthread

coordinator

interceptors

membershipListeners

channelListeners

optionCheck

Constructor Detail

GroupChannel

Method Detail

addInterceptor

heartbeat

send

send

messageReceived

sendNoRpcChannelReply

memberAdded

memberDisappeared

setupDefaultStack

checkOptionFlags

start

stop

getFirstInterceptor

getChannelReceiver

getChannelSender

getMembershipService

setChannelReceiver

setChannelSender

setMembershipService

addMembershipListener

removeMembershipListener

addChannelListener

removeChannelListener

getInterceptors

setOptionCheck

setHeartbeatSleeptime

setHeartbeat

getOptionCheck

getHeartbeat

getHeartbeatSleeptime