Class Channel
- java.lang.Object
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- org.jgroups.Channel
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
@Deprecated public class Channel extends java.lang.Object implements java.io.Closeable
Deprecated.UseJChannel
insteadA channel represents a group communication endpoint (like BSD datagram sockets). A client joins a group by connecting the channel to a group and leaves it by disconnecting. Messages sent over the channel are received by all group members that are connected to the same group (that is, all members that have the same group name). The FSM for a channel is roughly as follows: a channel is created (unconnected). The channel is connected to a group (connected). Messages can now be sent and received. The channel is disconnected from the group (unconnected). The channel could now be connected to a different group again. The channel is closed (closed). Only a single sender is allowed to be connected to a channel at a time, but there can be more than one channel in an application. Messages can be sent to the group members using the send method and messages can be received setting aReceiver
insetReceiver(Receiver)
and implementing theMessageListener.receive(Message)
callback.A channel instance is created using the public constructor.
Various degrees of sophistication in message exchange can be achieved using building blocks on top of channels; e.g., light-weight groups, synchronous message invocation, or remote method calls. Channels are on the same abstraction level as sockets, and should really be simple to use. Higher-level abstractions are all built on top of channels.- Since:
- 2.0
- Author:
- Bela Ban
- See Also:
DatagramPacket
,MulticastSocket
,JChannel
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
Channel.State
Deprecated.
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Method Summary
All Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description void
addChannelListener(ChannelListener listener)
Deprecated.Adds a ChannelListener instance that will be notified when a channel event such as connect, disconnect or close occurs.void
clearChannelListeners()
Deprecated.Clears all installed ChannelListener instancesvoid
close()
Deprecated.Destroys the channel and its associated resources (e.g., the protocol stack).void
connect(java.lang.String cluster_name)
Deprecated.Connects the channel to a group.void
connect(java.lang.String cluster_name, Address target, long timeout)
Deprecated.Connects this channel to a group and gets a state from a specified state provider.void
disconnect()
Deprecated.Disconnects the channel if it is connected.java.lang.Object
down(Event evt)
Deprecated.Enables access to event mechanism of a channel and is normally not used by clients directly.java.util.Map<java.lang.String,java.util.Map<java.lang.String,java.lang.Object>>
dumpStats()
Deprecated.Returns a map of statistics of the various protocols and of the channel itself.boolean
flushSupported()
Deprecated.Address
getAddress()
Deprecated.Returns the channel's own address.java.lang.String
getClusterName()
Deprecated.Returns the cluster name of the group of which the channel is a member.boolean
getDiscardOwnMessages()
Deprecated.Returns true if this channel will discard its own messages, false otherwisejava.lang.String
getName()
Deprecated.Returns the logical name of this channel if set.java.lang.String
getName(Address member)
Deprecated.Returns the logical name of a given member.java.lang.String
getProperties()
Deprecated.ProtocolStack
getProtocolStack()
Deprecated.Receiver
getReceiver()
Deprecated.Returns a receiver for this channel if it has been installed usingsetReceiver(Receiver)
, null otherwiseSocketFactory
getSocketFactory()
Deprecated.java.lang.String
getState()
Deprecated.void
getState(Address target, long timeout)
Deprecated.Retrieves the full state from the target member.UpHandler
getUpHandler()
Deprecated.Returns UpHandler installed for this channelView
getView()
Deprecated.Gets the current view.boolean
isClosed()
Deprecated.Determines whether the channel is in the closed state.boolean
isConnected()
Deprecated.Determines whether the channel is connected to a group.boolean
isConnecting()
Deprecated.Determines whether the channel is in the connecting state; this meansconnect(String)
has been called, but hasn't returned yetboolean
isOpen()
Deprecated.Determines whether the channel is open; ie.Channel
name(java.lang.String name)
Deprecated.Names a channel, same assetName(String)
void
removeChannelListener(ChannelListener listener)
Deprecated.Removes a ChannelListener previously installedvoid
send(Address dst, byte[] buf)
Deprecated.Sends a message.void
send(Address dst, byte[] buf, int offset, int length)
Deprecated.Sends a message to a destination.void
send(Address dst, java.lang.Object obj)
Deprecated.Helper method to create a Message with given parameters and invokesend(Message)
.void
send(Message msg)
Deprecated.Sends a message.void
setDiscardOwnMessages(boolean flag)
Deprecated.When set to true, all messages sent by a member A will be discarded by A.void
setName(java.lang.String name)
Deprecated.Sets the logical name for the channel.void
setReceiver(Receiver r)
Deprecated.Sets the receiver for this channel.void
setSocketFactory(SocketFactory factory)
Deprecated.void
setUpHandler(UpHandler up_handler)
Deprecated.Sets this channel event handler to be a recipient off all events .void
startFlush(boolean automatic_resume)
Deprecated.Performs the flush of the cluster, ie.void
startFlush(java.util.List<Address> flushParticipants, boolean automatic_resume)
Deprecated.Performs the flush of the cluster but only for the specified flush participants.void
stopFlush()
Deprecated.Stops the current flush of the cluster.void
stopFlush(java.util.List<Address> flushParticipants)
Deprecated.Stops the current flush of the cluster for the specified flush participants.
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Field Detail
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ch
protected final JChannel ch
Deprecated.
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Constructor Detail
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Channel
public Channel(JChannel ch)
Deprecated.
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Method Detail
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getState
public java.lang.String getState()
Deprecated.
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getProtocolStack
public ProtocolStack getProtocolStack()
Deprecated.
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getSocketFactory
public SocketFactory getSocketFactory()
Deprecated.
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setSocketFactory
public void setSocketFactory(SocketFactory factory)
Deprecated.
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connect
public void connect(java.lang.String cluster_name) throws java.lang.Exception
Deprecated.Connects the channel to a group. The client is now able to receive group messages, views and to send messages to (all or single) group members. This is a null operation if already connected.All channels with the same name form a group, that means all messages sent to the group will be received by all channels connected to the same cluster name.
- Parameters:
cluster_name
- The name of the channel to connect to.- Throws:
java.lang.Exception
- The protocol stack cannot be startedjava.lang.IllegalStateException
- The channel is closed
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connect
public void connect(java.lang.String cluster_name, Address target, long timeout) throws java.lang.Exception
Deprecated.Connects this channel to a group and gets a state from a specified state provider. This method essentially invokesconnect
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 succession. If the channel is closed an exception will be thrown.
- Parameters:
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.timeout
- the timeout for state transfer.- Throws:
java.lang.Exception
- Connecting to the cluster or state transfer was not successfuljava.lang.IllegalStateException
- The channel is closed and therefore cannot be used
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disconnect
public void disconnect()
Deprecated.Disconnects the channel if it is connected. If the channel is closed or disconnected, this operation is ignored
The channel can then be connected to the same or a different cluster again.- See Also:
connect(String)
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close
public void close()
Deprecated.Destroys the channel and its associated resources (e.g., the protocol stack). After a channel has been closed, invoking methods on it throws theChannelClosed
exception (or results in a null operation). It is a null operation if the channel is already closed.If the channel is connected to a group,
disconnect()
will be called first.- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
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isOpen
public boolean isOpen()
Deprecated.Determines whether the channel is open; ie. the protocol stack has been created (may not be connected though).- Returns:
- true is channel is open, false otherwise
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isConnected
public boolean isConnected()
Deprecated.Determines whether the channel is connected to a group.- Returns:
- true if channel is connected to cluster (group) and can send/receive messages, false otherwise
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isConnecting
public boolean isConnecting()
Deprecated.Determines whether the channel is in the connecting state; this meansconnect(String)
has been called, but hasn't returned yet- Returns:
- true if the channel is in the connecting state, false otherwise
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isClosed
public boolean isClosed()
Deprecated.Determines whether the channel is in the closed state.- Returns:
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dumpStats
public java.util.Map<java.lang.String,java.util.Map<java.lang.String,java.lang.Object>> dumpStats()
Deprecated.Returns a map of statistics of the various protocols and of the channel itself.- Returns:
- Map
. A map where the keys are the protocols ("channel" pseudo key is used for the channel itself") and the values are property maps.
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send
public void send(Message msg) throws java.lang.Exception
Deprecated.Sends a message. The message contains- a destination address (Address). A
null
address sends the message to all group members. - a source address. Can be left empty as it will be assigned automatically
- a byte buffer. The message contents.
- several additional fields. They can be used by application programs (or patterns). E.g. a message ID, flags etc
- Parameters:
msg
- The message to be sent. Destination and buffer should be set. A null destination means to send to all group members.- Throws:
java.lang.IllegalStateException
- thrown if the channel is disconnected or closedjava.lang.Exception
- a destination address (Address). A
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send
public void send(Address dst, java.lang.Object obj) throws java.lang.Exception
Deprecated.Helper method to create a Message with given parameters and invokesend(Message)
.- Parameters:
dst
- Destination address for message. If null, message will be sent to all current group membersobj
- A serializable object. Will be marshalled into the byte buffer of the Message. If it is not serializable, an exception will be thrown- Throws:
java.lang.Exception
- exception thrown if message sending was not successful
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send
public void send(Address dst, byte[] buf) throws java.lang.Exception
Deprecated.Sends a message. Seesend(Address,byte[],int,int)
for details- Parameters:
dst
- destination address for message. If null, message will be sent to all current group membersbuf
- buffer message payload- Throws:
java.lang.Exception
- exception thrown if message sending was not successful
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send
public void send(Address dst, byte[] buf, int offset, int length) throws java.lang.Exception
Deprecated.Sends a message to a destination.- Parameters:
dst
- The destination address. If null, the message will be sent to all cluster nodes (= group members)buf
- The buffer to be sentoffset
- The offset into the bufferlength
- The length of the data to be sent. Has to be <= buf.length - offset. This will sendlength
bytes starting atoffset
- Throws:
java.lang.Exception
- If send() failed
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down
public java.lang.Object down(Event evt)
Deprecated.Enables access to event mechanism of a channel and is normally not used by clients directly.- Parameters:
evt
- sends an Event to a specific protocol layer and receives a response.- Returns:
- a response from a particular protocol layer targeted by Event parameter
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getView
public View getView()
Deprecated.Gets the current view. The view may only be available after a successfulconnect()
. The result of calling this method on an unconnected channel is implementation defined (may return null). Calling this method on a closed channel returns a null view.- Returns:
- The current view.
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getAddress
public Address getAddress()
Deprecated.Returns the channel's own address. The result of calling this method on an unconnected channel is implementation defined (may return null). Calling this method on a closed channel returns null. Addresses can be used as destination in thesend()
operation.- Returns:
- The channel's address (opaque)
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getName
public java.lang.String getName()
Deprecated.Returns the logical name of this channel if set.- Returns:
- The logical name or null (if not set)
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getName
public java.lang.String getName(Address member)
Deprecated.Returns the logical name of a given member. The lookup is from the local cache of logical address / logical name mappings and no remote communication is performed.- Parameters:
member
-- Returns:
- The logical name for
member
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setName
public void setName(java.lang.String name)
Deprecated.Sets the logical name for the channel. The name will stay associated with this channel for the channel's lifetime (until close() is called). This method should be called before calling connect().- Parameters:
name
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name
public Channel name(java.lang.String name)
Deprecated.Names a channel, same assetName(String)
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getClusterName
public java.lang.String getClusterName()
Deprecated.Returns the cluster name of the group of which the channel is a member. This is the object that was the argument toconnect()
. Calling this method on a closed channel returnsnull
.- Returns:
- The cluster name
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getProperties
public java.lang.String getProperties()
Deprecated.
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setUpHandler
public void setUpHandler(UpHandler up_handler)
Deprecated.Sets this channel event handler to be a recipient off all events . These will not be received by the channel (except connect/disconnect, state retrieval and the like). This can be used by building blocks on top of a channel; thus the channel is used as a pass-through medium, and the building blocks take over some of the channel's tasks. However, tasks such as connection management and state transfer is still handled by the channel.- Parameters:
up_handler
- handler to handle channel events
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getUpHandler
public UpHandler getUpHandler()
Deprecated.Returns UpHandler installed for this channel- Returns:
- the installed UpHandler implementation
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addChannelListener
public void addChannelListener(ChannelListener listener)
Deprecated.Adds a ChannelListener instance that will be notified when a channel event such as connect, disconnect or close occurs.- Parameters:
listener
- to be notified
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removeChannelListener
public void removeChannelListener(ChannelListener listener)
Deprecated.Removes a ChannelListener previously installed- Parameters:
listener
- to be removed
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clearChannelListeners
public void clearChannelListeners()
Deprecated.Clears all installed ChannelListener instances
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setReceiver
public void setReceiver(Receiver r)
Deprecated.Sets the receiver for this channel. Receiver will in turn handle all messages, view changes, implement state transfer logic and so on.- Parameters:
r
- the receiver instance for this channel- See Also:
Receiver
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getReceiver
public Receiver getReceiver()
Deprecated.Returns a receiver for this channel if it has been installed usingsetReceiver(Receiver)
, null otherwise- Returns:
- a receiver installed on this channel
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setDiscardOwnMessages
public void setDiscardOwnMessages(boolean flag)
Deprecated.When set to true, all messages sent by a member A will be discarded by A.- Parameters:
flag
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getDiscardOwnMessages
public boolean getDiscardOwnMessages()
Deprecated.Returns true if this channel will discard its own messages, false otherwise- Returns:
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flushSupported
public boolean flushSupported()
Deprecated.
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startFlush
public void startFlush(java.util.List<Address> flushParticipants, boolean automatic_resume) throws java.lang.Exception
Deprecated.Performs the flush of the cluster but only for the specified flush participants. All pending messages are flushed out but only for the flush participants. The remaining members in the cluster are not included in the flush. The list of flush participants should be a proper subset of the current view. If this flush is not automatically resumed it is an obligation of the application to invoke the matchingstopFlush(List)
method with the same list of members used instartFlush(List, boolean)
.- Parameters:
automatic_resume
- if true callstopFlush()
after the flush- Throws:
java.lang.Exception
- See Also:
startFlush(boolean)
,Util#startFlush(Channel, List, int, long, long)
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startFlush
public void startFlush(boolean automatic_resume) throws java.lang.Exception
Deprecated.Performs the flush of the cluster, ie. all pending application messages are flushed out of the cluster and all members ack their reception. After this call returns, no member will be allowed to send any messages untilstopFlush()
is called. In the case of flush collisions (another member attempts flush at roughly the same time) start flush will fail by throwing an Exception. Applications can re-attempt flushing after certain back-off period. JGroups provides a helper random sleep time backoff algorithm for flush using Util class.- Parameters:
automatic_resume
- if true callstopFlush()
after the flush- Throws:
java.lang.Exception
- See Also:
Util#startFlush(Channel, List, int, long, long)
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stopFlush
public void stopFlush()
Deprecated.Stops the current flush of the cluster. Cluster members are unblocked and allowed to send new and pending messages.- See Also:
startFlush(boolean)
,startFlush(List, boolean)
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stopFlush
public void stopFlush(java.util.List<Address> flushParticipants)
Deprecated.Stops the current flush of the cluster for the specified flush participants. Flush participants are unblocked and allowed to send new and pending messages.It is an obligation of the application to invoke the matching
startFlush(List, boolean)
method with the same list of members prior to invocation of this method.- Parameters:
flushParticipants
- the flush participants
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getState
public void getState(Address target, long timeout) throws java.lang.Exception
Deprecated.Retrieves the full state from the target member.State transfer is initiated by invoking getState on this channel. The state provider in turn invokes
StateListener.getState(java.io.OutputStream)
callback and sends a state to this node, the state receiver. After the state arrives to the state receiverStateListener.setState(java.io.InputStream)
callback is invoked to install the state.- Parameters:
target
- The state provider. If null the coordinator is used by defaulttimeout
- The number of milliseconds to wait for the operation to complete successfully. 0 waits until the state has been received- Throws:
java.lang.IllegalStateException
- The channel was closed or disconnected, or the flush (if present) failedStateTransferException
- raised if there was a problem during the state transferjava.lang.Exception
- See Also:
StateListener.getState(java.io.OutputStream)
,StateListener.setState(java.io.InputStream)
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