Class SocketAppender
- All Implemented Interfaces:
Appender,OptionHandler
LoggingEvent objects to a remote a log server, usually a SocketNode.
The SocketAppender has the following properties:
- If sent to a
SocketNode, remote logging is non-intrusive as far as the log event is concerned. In other words, the event will be logged with the same time stamp,NDC, location info as if it were logged locally by the client. - SocketAppenders do not use a layout. They ship a serialized
LoggingEventobject to the server side. - Remote logging uses the TCP protocol. Consequently, if the server is
reachable, then log events will eventually arrive at the server.
- If the remote server is down, the logging requests are simply dropped.
However, if and when the server comes back up, then event transmission is
resumed transparently. This transparent reconneciton is performed by a
connector thread which periodically attempts to connect to the
server.
- Logging events are automatically buffered by the native TCP
implementation. This means that if the link to server is slow but still
faster than the rate of (log) event production by the client, the client will
not be affected by the slow network connection. However, if the network
connection is slower then the rate of event production, then the client can
only progress at the network rate. In particular, if the network link to the
the server is down, the client will be blocked.
On the other hand, if the network link is up, but the server is down, the client will not be blocked when making log requests but the log events will be lost due to server unavailability.
- Even if a
SocketAppenderis no longer attached to any category, it will not be garbage collected in the presence of a connector thread. A connector thread exists only if the connection to the server is down. To avoid this garbage collection problem, you shouldclose()the theSocketAppenderexplicitly. See also next item.Long lived applications which create/destroy many
SocketAppenderinstances should be aware of this garbage collection problem. Most other applications can safely ignore it. - If the JVM hosting the
SocketAppenderexits before theSocketAppenderis closed either explicitly or subsequent to garbage collection, then there might be untransmitted data in the pipe which might be lost. This is a common problem on Windows based systems.To avoid lost data, it is usually sufficient to
close()theSocketAppendereither explicitly or by calling theLogManager.shutdown()method before exiting the application.
- Since:
- 0.8.4
- Author:
- Ceki Gülcü
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final intThe default port number of remote logging server (4560).static final StringThe MulticastDNS zone advertised by a SocketAppenderFields inherited from class org.apache.log4j.AppenderSkeleton
closed, errorHandler, headFilter, layout, name, tailFilter, threshold -
Constructor Summary
ConstructorsConstructorDescriptionSocketAppender(String host, int port) Connects to remote server athostandport.SocketAppender(InetAddress address, int port) Connects to remote server ataddressandport. -
Method Summary
Modifier and TypeMethodDescriptionvoidConnect to the specified RemoteHost and Port.voidappend(LoggingEvent event) Subclasses ofAppenderSkeletonshould implement this method to perform actual logging.voidcleanUp()Drop the connection to the remote host and release the underlying connector thread if it has been createdvoidclose()Close this appender.Returns value of the Application option.booleanReturns value of the LocationInfo option.intgetPort()Returns value of the Port option.intReturns value of the ReconnectionDelay option.Returns value of the RemoteHost option.booleanbooleanThe SocketAppender does not use a layout.voidsetAdvertiseViaMulticastDNS(boolean advertiseViaMulticastDNS) voidsetApplication(String lapp) The App option takes a string value which should be the name of the application getting logged.voidsetLocationInfo(boolean locationInfo) The LocationInfo option takes a boolean value.voidsetPort(int port) The Port option takes a positive integer representing the port where the server is waiting for connections.voidsetReconnectionDelay(int delay) The ReconnectionDelay option takes a positive integer representing the number of milliseconds to wait between each failed connection attempt to the server.voidsetRemoteHost(String host) The RemoteHost option takes a string value which should be the host name of the server where aSocketNodeis running.Methods inherited from class org.apache.log4j.AppenderSkeleton
addFilter, clearFilters, doAppend, finalize, getErrorHandler, getFilter, getFirstFilter, getLayout, getName, getThreshold, isAsSevereAsThreshold, setErrorHandler, setLayout, setName, setThreshold
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Field Details
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DEFAULT_PORT
public static final int DEFAULT_PORTThe default port number of remote logging server (4560).- Since:
- 1.2.15
- See Also:
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ZONE
The MulticastDNS zone advertised by a SocketAppender- See Also:
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Constructor Details
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SocketAppender
public SocketAppender() -
SocketAppender
Connects to remote server ataddressandport. -
SocketAppender
Connects to remote server athostandport.
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Method Details
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activateOptions
public void activateOptions()Connect to the specified RemoteHost and Port.- Specified by:
activateOptionsin interfaceOptionHandler- Overrides:
activateOptionsin classAppenderSkeleton
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close
public void close()Close this appender.This will mark the appender as closed and call then
cleanUp()method. -
cleanUp
public void cleanUp()Drop the connection to the remote host and release the underlying connector thread if it has been created -
append
Description copied from class:AppenderSkeletonSubclasses ofAppenderSkeletonshould implement this method to perform actual logging. See alsoAppenderSkeleton.doAppendmethod.- Specified by:
appendin classAppenderSkeleton
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setAdvertiseViaMulticastDNS
public void setAdvertiseViaMulticastDNS(boolean advertiseViaMulticastDNS) -
isAdvertiseViaMulticastDNS
public boolean isAdvertiseViaMulticastDNS() -
requiresLayout
public boolean requiresLayout()The SocketAppender does not use a layout. Hence, this method returnsfalse. -
setRemoteHost
The RemoteHost option takes a string value which should be the host name of the server where aSocketNodeis running. -
getRemoteHost
Returns value of the RemoteHost option. -
setPort
public void setPort(int port) The Port option takes a positive integer representing the port where the server is waiting for connections. -
getPort
public int getPort()Returns value of the Port option. -
setLocationInfo
public void setLocationInfo(boolean locationInfo) The LocationInfo option takes a boolean value. If true, the information sent to the remote host will include location information. By default no location information is sent to the server. -
getLocationInfo
public boolean getLocationInfo()Returns value of the LocationInfo option. -
setApplication
The App option takes a string value which should be the name of the application getting logged. If property was already set (via system property), don't set here.- Since:
- 1.2.15
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getApplication
Returns value of the Application option.- Since:
- 1.2.15
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setReconnectionDelay
public void setReconnectionDelay(int delay) The ReconnectionDelay option takes a positive integer representing the number of milliseconds to wait between each failed connection attempt to the server. The default value of this option is 30000 which corresponds to 30 seconds.Setting this option to zero turns off reconnection capability.
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getReconnectionDelay
public int getReconnectionDelay()Returns value of the ReconnectionDelay option.
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