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java.lang.Objectorg.jgroups.Channel
org.jgroups.JChannel
public class JChannel
JChannel is a pure Java implementation of Channel. When a JChannel object is instantiated it automatically sets up the protocol stack.
Properties
Properties are used to configure a channel, and are accepted in several forms; the String form is described here. A property string consists of a number of properties separated by colons. For example:
"<prop1>(arg1=val1):<prop2>(arg1=val1;arg2=val2):<prop3>:<propn>"
Each property relates directly to a protocol layer, which is
implemented as a Java class. When a protocol stack is to be created
based on the above property string, the first property becomes the
bottom-most layer, the second one will be placed on the first, etc.:
the stack is created from the bottom to the top, as the string is
parsed from left to right. Each property has to be the name of a
Java class that resides in the
org.jgroups.protocols
package.
Note that only the base name has to be given, not the fully specified class name (e.g., UDP instead of org.jgroups.protocols.UDP).
Each layer may have 0 or more arguments, which are specified as a list of name/value pairs in parentheses directly after the property. In the example above, the first protocol layer has 1 argument, the second 2, the third none. When a layer is created, these properties (if there are any) will be set in a layer by invoking the layer's setProperties() method
As an example the property string below instructs JGroups to create a JChannel with protocols UDP, PING, FD and GMS:
"UDP(mcast_addr=228.10.9.8;mcast_port=5678):PING:FD:GMS"
The UDP protocol layer is at the bottom of the stack, and it
should use mcast address 228.10.9.8. and port 5678 rather than
the default IP multicast address and port. The only other argument
instructs FD to output debug information while executing.
Property UDP refers to a class UDP
,
which is subsequently loaded and an instance of which is created as protocol layer.
If any of these classes are not found, an exception will be thrown and
the construction of the stack will be aborted.
Field Summary | |
---|---|
protected java.util.Map<java.lang.String,java.lang.Object> |
additional_data
Provides storage for arbitrary objects. |
protected boolean |
closed
|
protected org.jgroups.JChannel.CloserThread |
closer
Thread responsible for closing a channel and potentially reconnecting to it (e.g., when shunned). |
protected boolean |
connected
|
static java.lang.String |
DEFAULT_PROTOCOL_STACK
The default protocol stack used by the default constructor. |
protected java.util.concurrent.ConcurrentMap<java.lang.String,java.lang.Object> |
info
|
protected org.apache.commons.logging.Log |
log
|
protected long |
received_bytes
|
protected long |
received_msgs
|
protected long |
sent_bytes
|
protected long |
sent_msgs
|
protected boolean |
stats
Collect statistics |
Fields inherited from class org.jgroups.Channel |
---|
AUTO_GETSTATE, AUTO_RECONNECT, BLOCK, channel_listeners, GET_STATE_EVENTS, LOCAL, receiver, SUSPECT, up_handler, VIEW |
Constructor Summary | |
---|---|
|
JChannel()
Constructs a JChannel instance with the protocol stack
specified by the DEFAULT_PROTOCOL_STACK member. |
protected |
JChannel(boolean no_op)
Used by subclass to create a JChannel without a protocol stack, don't use as application programmer |
|
JChannel(org.w3c.dom.Element properties)
Constructs a JChannel instance with the protocol stack
configuration contained by the specified XML element. |
|
JChannel(java.io.File properties)
Constructs a JChannel instance with the protocol stack
configuration contained by the specified file. |
|
JChannel(java.lang.Object properties)
Deprecated. Use the constructors with specific parameter types instead. |
|
JChannel(ProtocolStackConfigurator configurator)
Constructs a JChannel instance with the protocol stack
configuration contained by the protocol stack configurator parameter. |
|
JChannel(java.lang.String properties)
Constructs a JChannel instance with the protocol stack
configuration based upon the specified properties parameter. |
|
JChannel(java.net.URL properties)
Constructs a JChannel instance with the protocol stack
configuration indicated by the specified URL. |
Method Summary | |
---|---|
protected void |
_close(boolean disconnect,
boolean close_mq)
Disconnects and closes the channel. |
void |
blockOk()
Called to acknowledge a block() (callback in MembershipListener or
BlockEvent received from call to receive() ). |
protected void |
checkClosed()
health check throws a ChannelClosed exception if the channel is closed |
protected void |
checkClosedOrNotConnected()
|
void |
close()
Destroys the channel. |
void |
closeMessageQueue(boolean flush_entries)
|
void |
connect(java.lang.String cluster_name)
Connects the channel to a group. |
void |
connect(java.lang.String cluster_name,
Address target,
java.lang.String state_id,
long timeout)
Connects this channel to a group and gets a state from a specified state provider. |
void |
disconnect()
Disconnects the channel if it is connected. |
void |
down(Event evt)
Sends a message through the protocol stack if the stack is available |
java.lang.Object |
downcall(Event evt)
Can be used instead of down() when a return value is expected. |
protected java.util.Map<java.lang.String,java.lang.Long> |
dumpChannelStats()
|
java.lang.String |
dumpQueue()
|
java.util.Map<java.lang.String,java.lang.Object> |
dumpStats()
Returns a map of statistics of the various protocols and of the channel itself. |
java.util.Map<java.lang.String,java.lang.Object> |
dumpStats(java.lang.String protocol_name)
|
java.lang.String |
dumpTimerQueue()
|
void |
enableStats(boolean stats)
|
boolean |
flushSupported()
|
boolean |
getAllStates(java.util.Vector targets,
long timeout)
Deprecated. Not really needed - we always want to get the state from a single member, use getState(org.jgroups.Address, long) instead |
java.lang.String |
getChannelName()
Deprecated. Use getClusterName() instead |
java.lang.String |
getClusterName()
Returns the cluster name of the group of which the channel is a member. |
java.util.Map<java.lang.String,java.lang.Object> |
getInfo()
|
Address |
getLocalAddress()
returns the local address of the channel returns null if the channel is closed |
java.lang.String |
getLocalAddressAsString()
|
protected org.apache.commons.logging.Log |
getLog()
|
int |
getNumberOfTasksInTimer()
|
int |
getNumMessages()
Returns the number of messages that are waiting. |
java.lang.Object |
getOpt(int option)
returns the value of an option. |
java.lang.String |
getProperties()
returns the protocol stack configuration in string format. |
ProtocolStack |
getProtocolStack()
Returns the protocol stack. |
long |
getReceivedBytes()
|
long |
getReceivedMessages()
|
long |
getSentBytes()
|
long |
getSentMessages()
|
boolean |
getState(Address target,
long timeout)
Retrieves a full state from the target member. |
boolean |
getState(Address target,
java.lang.String state_id,
long timeout)
Retrieves a substate (or partial state) indicated by state_id from the target member. |
boolean |
getState(Address target,
java.lang.String state_id,
long timeout,
boolean useFlushIfPresent)
Retrieves a substate (or partial state) indicated by state_id from the target member. |
int |
getTimerThreads()
|
View |
getView()
Returns the current view. |
protected void |
init(ProtocolStackConfigurator configurator)
|
boolean |
isConnected()
returns true if the Connect operation has been called successfully |
boolean |
isOpen()
returns true if the Open operation has been called successfully |
void |
open()
Opens the channel. |
java.lang.Object |
peek(long timeout)
Just peeks at the next message, view or block. |
java.lang.String |
printProtocolSpec(boolean include_properties)
Returns a pretty-printed form of all the protocols. |
java.lang.Object |
receive(long timeout)
Deprecated. Use a Receiver instead |
void |
resetStats()
|
void |
returnState(byte[] state)
Called by the application is response to receiving a getState() object when
calling receive() . |
void |
returnState(byte[] state,
java.lang.String state_id)
Returns a substate as indicated by state_id |
void |
send(Address dst,
Address src,
java.io.Serializable obj)
creates a new message with the destination address, and the source address and the object as the message value |
void |
send(Message msg)
Sends a message through the protocol stack. |
void |
setInfo(java.lang.String key,
java.lang.Object value)
|
void |
setOpt(int option,
java.lang.Object value)
Sets a channel option. |
void |
shutdown()
Shuts down the channel without disconnecting |
boolean |
startFlush(boolean automatic_resume)
Will perform a flush of the system, ie. |
boolean |
startFlush(java.util.List<Address> flushParticipants,
boolean automatic_resume)
Performs a partial flush in a cluster for flush participants. |
boolean |
startFlush(long timeout,
boolean automatic_resume)
Will perform a flush of the system, ie. |
boolean |
statsEnabled()
|
void |
stopFlush()
|
void |
stopFlush(java.util.List<Address> flushParticipants)
|
protected void |
stopStack(boolean disconnect,
boolean destroy)
|
java.lang.String |
toString(boolean details)
|
java.lang.Object |
up(Event evt)
Callback method Called by the ProtocolStack when a message is received. |
Methods inherited from class org.jgroups.Channel |
---|
addChannelListener, clearChannelListeners, notifyChannelClosed, notifyChannelConnected, notifyChannelDisconnected, notifyChannelReconnected, notifyChannelShunned, option2String, removeChannelListener, setChannelListener, setReceiver, setUpHandler |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
public static final java.lang.String DEFAULT_PROTOCOL_STACK
protected org.jgroups.JChannel.CloserThread closer
protected volatile boolean connected
protected volatile boolean closed
protected final java.util.Map<java.lang.String,java.lang.Object> additional_data
protected final java.util.concurrent.ConcurrentMap<java.lang.String,java.lang.Object> info
protected final org.apache.commons.logging.Log log
protected boolean stats
protected long sent_msgs
protected long received_msgs
protected long sent_bytes
protected long received_bytes
Constructor Detail |
---|
protected JChannel(boolean no_op)
public JChannel() throws ChannelException
JChannel
instance with the protocol stack
specified by the DEFAULT_PROTOCOL_STACK
member.
ChannelException
- if problems occur during the initialization of
the protocol stack.public JChannel(java.io.File properties) throws ChannelException
JChannel
instance with the protocol stack
configuration contained by the specified file.
properties
- a file containing a JGroups XML protocol stack
configuration.
ChannelException
- if problems occur during the configuration or
initialization of the protocol stack.public JChannel(org.w3c.dom.Element properties) throws ChannelException
JChannel
instance with the protocol stack
configuration contained by the specified XML element.
properties
- a XML element containing a JGroups XML protocol stack
configuration.
ChannelException
- if problems occur during the configuration or
initialization of the protocol stack.public JChannel(java.net.URL properties) throws ChannelException
JChannel
instance with the protocol stack
configuration indicated by the specified URL.
properties
- a URL pointing to a JGroups XML protocol stack
configuration.
ChannelException
- if problems occur during the configuration or
initialization of the protocol stack.public JChannel(java.lang.String properties) throws ChannelException
JChannel
instance with the protocol stack
configuration based upon the specified properties parameter.
properties
- an old style property string, a string representing a
system resource containing a JGroups XML configuration,
a string representing a URL pointing to a JGroups XML
XML configuration, or a string representing a file name
that contains a JGroups XML configuration.
ChannelException
- if problems occur during the configuration and
initialization of the protocol stack.public JChannel(ProtocolStackConfigurator configurator) throws ChannelException
JChannel
instance with the protocol stack
configuration contained by the protocol stack configurator parameter.
All of the public constructors of this class eventually delegate to this method.
configurator
- a protocol stack configurator containing a JGroups
protocol stack configuration.
ChannelException
- if problems occur during the initialization of
the protocol stack.public JChannel(java.lang.Object properties) throws ChannelException
properties
- the protocol stack setup; if null, the default protocol stack will be used.
The properties can also be a java.net.URL object or a string that is a URL spec.
The JChannel will validate any URL object and String object to see if they are a URL.
In case of the parameter being a url, the JChannel will try to load the xml from there.
In case properties is a org.w3c.dom.Element, the ConfiguratorFactory will parse the
DOM tree with the element as its root element.
ChannelException
Method Detail |
---|
public ProtocolStack getProtocolStack()
protected org.apache.commons.logging.Log getLog()
getLog
in class Channel
public java.lang.String getProperties()
public boolean statsEnabled()
public void enableStats(boolean stats)
public void resetStats()
public long getSentMessages()
public long getSentBytes()
public long getReceivedMessages()
public long getReceivedBytes()
public int getNumberOfTasksInTimer()
public int getTimerThreads()
public java.lang.String dumpTimerQueue()
public java.lang.String printProtocolSpec(boolean include_properties)
public void connect(java.lang.String cluster_name) throws ChannelException
connect
in class Channel
cluster_name
- A String
denoting the group name. Cannot be null.
ChannelException
- The protocol stack cannot be started
ChannelClosedException
- The channel is closed and therefore cannot be used any longer.
A new channel has to be created first.Channel.disconnect()
public void connect(java.lang.String cluster_name, Address target, java.lang.String state_id, long timeout) throws ChannelException
This method essentially invokes
connect
and
getState
methods successively.
If FLUSH protocol is in channel's stack definition only one flush is executed for both connecting and
fetching state rather than two flushes if we invoke
connect
and
getState
in succesion.
If the channel is already connected, an error message will be printed to the error log.
If the channel is closed a ChannelClosed exception will be thrown.
cluster_name
- the cluster name to connect to. Cannot be null.target
- the state provider. If null state will be fetched from coordinator, unless this channel is coordinator.state_id
- the substate id for partial state transfer. If null entire state will be transferred.timeout
- the timeout for state transfer.
ChannelException
- The protocol stack cannot be started
ChannelException
- Connecting to cluster was not successful
ChannelClosedException
- The channel is closed and therefore cannot be used any longer.
A new channel has to be created first.
StateTransferException
- State transfer was not successful
public void disconnect()
disconnect
in class Channel
Channel.connect(String)
public void close()
close
in class Channel
public void shutdown()
shutdown
in class Channel
public void open() throws ChannelException
open
in class Channel
ChannelException
public boolean isOpen()
isOpen
in class Channel
public boolean isConnected()
isConnected
in class Channel
public int getNumMessages()
Channel
Channel.receive(long)
. Note that this number could change after
calling this method and before calling receive() (e.g. the latter
method might be called by a different thread).
getNumMessages
in class Channel
public java.lang.String dumpQueue()
dumpQueue
in class Channel
public java.util.Map<java.lang.String,java.lang.Object> dumpStats()
dumpStats
in class Channel
public java.util.Map<java.lang.String,java.lang.Object> dumpStats(java.lang.String protocol_name)
protected java.util.Map<java.lang.String,java.lang.Long> dumpChannelStats()
public void send(Message msg) throws ChannelNotConnectedException, ChannelClosedException
send
in interface Transport
send
in class Channel
msg
- the message to be sent through the protocol stack,
the destination of the message is specified inside the message itself
ChannelNotConnectedException
ChannelClosedException
public void send(Address dst, Address src, java.io.Serializable obj) throws ChannelNotConnectedException, ChannelClosedException
send
in class Channel
dst
- - the destination address of the message, null for all memberssrc
- - the source address of the messageobj
- - the value of the message
ChannelNotConnectedException
ChannelClosedException
send(org.jgroups.Message)
public java.lang.Object receive(long timeout) throws ChannelNotConnectedException, ChannelClosedException, TimeoutException
Receiver
instead
receive
in interface Transport
receive
in class Channel
timeout
- the number of milliseconds to wait if the receive queue is empty. 0 means wait forever
TimeoutException
- if a timeout occured prior to a new message was received
ChannelNotConnectedException
ChannelClosedException
peek(long)
public java.lang.Object peek(long timeout) throws ChannelNotConnectedException, ChannelClosedException, TimeoutException
peek
in class Channel
timeout
- Value in milliseconds. Value <= 0 means wait forever
ChannelNotConnectedException
- The channel must be connected to receive messages.
ChannelClosedException
- The channel is closed and therefore cannot be used any longer.
A new channel has to be created first.
TimeoutException
- Thrown when a timeout has occurred.Channel.receive(long)
public View getView()
getView
in class Channel
public Address getLocalAddress()
getLocalAddress
in class Channel
Send
operation.public java.lang.String getLocalAddressAsString()
public java.lang.String getChannelName()
getClusterName()
instead
getChannelName
in class Channel
public java.lang.String getClusterName()
Channel
connect()
. Calling this method on a closed
channel returns null
.
getClusterName
in class Channel
public void setOpt(int option, java.lang.Object value)
There are certain dependencies between the options that you can set, I will try to describe them here.
Option: Channel.BLOCK
Value: java.lang.Boolean
Result: set to true will set setOpt(VIEW, true) and the JChannel will receive BLOCKS and VIEW events
Option: LOCAL
Value: java.lang.Boolean
Result: set to true the JChannel will receive messages that it self sent out.
Option: AUTO_RECONNECT
Value: java.lang.Boolean
Result: set to true and the JChannel will try to reconnect when it is being closed
Option: AUTO_GETSTATE
Value: java.lang.Boolean
Result: set to true, the AUTO_RECONNECT will be set to true and the JChannel will try to get the state after a close and reconnect happens
setOpt
in class Channel
option
- the parameter option Channel.VIEW, Channel.SUSPECT, etcvalue
- the value to set for this optionpublic java.lang.Object getOpt(int option)
getOpt
in class Channel
option
- the option you want to see the value for
setOpt(int, java.lang.Object)
public void blockOk()
MembershipListener
or
BlockEvent
received from call to receive()
).
After sending blockOk(), no messages should be sent until a new view has been received.
Calling this method on a closed channel has no effect.
blockOk
in class Channel
public boolean getState(Address target, long timeout) throws ChannelNotConnectedException, ChannelClosedException
State transfer is initiated by invoking getState on this channel, state receiver, and sending a GET_STATE message to a target member - state provider. State provider passes GET_STATE message to application that is using the state provider channel which in turn provides an application state to a state receiver. Upon successful installation of a state at state receiver this method returns true.
getState
in class Channel
target
- State provider. If null, coordinator is usedstate_id
- The ID of the substate. If null, the entire state will be
transferredtimeout
- the number of milliseconds to wait for the operation to
complete successfully. 0 waits until the state has been
received
ChannelNotConnectedException
- if channel was not connected at the time state retrieval
was initiated
ChannelClosedException
- if channel was closed at the time state retrieval was
initiated
java.lang.IllegalStateException
- if one of state transfer protocols is not present in this
channel
java.lang.IllegalStateException
- if flush is used in this channel and cluster could not be
flushedExtendedMessageListener.getState(OutputStream)
,
ExtendedMessageListener.setState(InputStream)
,
MessageListener.getState()
,
MessageListener.setState(byte[])
public boolean getState(Address target, java.lang.String state_id, long timeout) throws ChannelNotConnectedException, ChannelClosedException
State transfer is initiated by invoking getState on this channel, state receiver, and sending a GET_STATE message to a target member - state provider. State provider passes GET_STATE message to application that is using the state provider channel which in turn provides an application state to a state receiver. Upon successful installation of a state at state receiver this method returns true.
getState
in class Channel
target
- State provider. If null, coordinator is usedstate_id
- The ID of the substate. If null, the entire state will be
transferredtimeout
- the number of milliseconds to wait for the operation to
complete successfully. 0 waits until the state has been
received
ChannelNotConnectedException
- if channel was not connected at the time state retrieval
was initiated
ChannelClosedException
- if channel was closed at the time state retrieval was
initiated
java.lang.IllegalStateException
- if one of state transfer protocols is not present in this
channel
java.lang.IllegalStateException
- if flush is used in this channel and cluster could not be
flushedExtendedMessageListener.getState(OutputStream)
,
ExtendedMessageListener.setState(InputStream)
,
MessageListener.getState()
,
MessageListener.setState(byte[])
public boolean getState(Address target, java.lang.String state_id, long timeout, boolean useFlushIfPresent) throws ChannelNotConnectedException, ChannelClosedException
State transfer is initiated by invoking getState on this channel, state receiver, and sending a GET_STATE message to a target member - state provider. State provider passes GET_STATE message to application that is using the state provider channel which in turn provides an application state to a state receiver. Upon successful installation of a state at state receiver this method returns true.
target
- State provider. If null, coordinator is usedstate_id
- The ID of the substate. If null, the entire state will be
transferredtimeout
- the number of milliseconds to wait for the operation to
complete successfully. 0 waits until the state has been
receiveduseFlushIfPresent
- whether channel should be flushed prior to state retrieval
ChannelNotConnectedException
- if channel was not connected at the time state retrieval
was initiated
ChannelClosedException
- if channel was closed at the time state retrieval was
initiated
java.lang.IllegalStateException
- if one of state transfer protocols is not present in this
channel
java.lang.IllegalStateException
- if flush is used in this channel and cluster could not be
flushedExtendedMessageListener.getState(OutputStream)
,
ExtendedMessageListener.setState(InputStream)
,
MessageListener.getState()
,
MessageListener.setState(byte[])
public boolean getAllStates(java.util.Vector targets, long timeout) throws ChannelNotConnectedException, ChannelClosedException
getState(org.jgroups.Address, long)
instead
timeout
milliseconds have elapsed. The argument of GET_STATE_OK should be a vector of objects.
getAllStates
in class Channel
targets
- - the target members to receive the state from ( an Address list )timeout
- - the number of milliseconds to wait for the operation to complete successfully
ChannelNotConnectedException
- The channel must be connected to
receive messages.
ChannelClosedException
- The channel is closed and therefore cannot be used
any longer. A new channel has to be created first.public void returnState(byte[] state)
getState()
object when
calling receive()
.
When the application receives a getState() message on the receive() method,
it should call returnState() to reply with the state of the application
returnState
in class Channel
state
- The state of the application as a byte buffer
(to send over the network).public void returnState(byte[] state, java.lang.String state_id)
returnState
in class Channel
state
- state_id
- public java.lang.Object up(Event evt)
Receive
s will dequeue it.
evt
- the event carrying the message from the protocol stackpublic void down(Event evt)
down
in class Channel
evt
- the message to send down, encapsulated in an eventpublic java.lang.Object downcall(Event evt)
Channel
downcall
in class Channel
public java.lang.String toString(boolean details)
protected final void init(ProtocolStackConfigurator configurator) throws ChannelException
ChannelException
protected void checkClosed() throws ChannelClosedException
ChannelClosedException
protected void checkClosedOrNotConnected() throws ChannelNotConnectedException, ChannelClosedException
ChannelNotConnectedException
ChannelClosedException
protected void _close(boolean disconnect, boolean close_mq)
this.disconnect
if the disconnect parameter is true
Queue.close
on mq if the close_mq parameter is true
ProtocolStack.stop
on the protocol stack
ProtocolStack.destroy
on the protocol stack
protected void stopStack(boolean disconnect, boolean destroy)
public final void closeMessageQueue(boolean flush_entries)
public boolean flushSupported()
flushSupported
in class Channel
public boolean startFlush(boolean automatic_resume)
stopFlush()
is called.
In case of flush collisions, random sleep time backoff algorithm is employed and flush is reattempted for numberOfAttempts. Therefore this method is guaranteed to return after timeout x numberOfAttempts miliseconds.
startFlush
in class Channel
automatic_resume
- Call stopFlush()
after the flush
public boolean startFlush(java.util.List<Address> flushParticipants, boolean automatic_resume)
All pending messages are flushed out only for flush participants. Remaining members in a cluster are not included in flush. Flush participants should be a proper subset of a current view.
In case of flush collisions, random sleep time backoff algorithm is employed and flush is reattempted for numberOfAttempts. Therefore this method is guaranteed to return after timeout x numberOfAttempts miliseconds.
startFlush
in class Channel
automatic_resume
- Call stopFlush()
after the flush
public boolean startFlush(long timeout, boolean automatic_resume)
stopFlush()
is called.
In case of flush collisions, random sleep time backoff algorithm is employed and flush is reattempted for numberOfAttempts. Therefore this method is guaranteed to return after timeout x numberOfAttempts miliseconds.
startFlush
in class Channel
timeout
- automatic_resume
- Call stopFlush()
after the flush
public void stopFlush()
stopFlush
in class Channel
public void stopFlush(java.util.List<Address> flushParticipants)
stopFlush
in class Channel
public java.util.Map<java.lang.String,java.lang.Object> getInfo()
getInfo
in class Channel
public void setInfo(java.lang.String key, java.lang.Object value)
setInfo
in class Channel
|
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