org.apache.log4j.net
Class SocketAppender
- Appender, OptionHandler
public class SocketAppender
Sends
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
LoggingEvent
object 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
SocketAppender
is 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 should close()
the the
SocketAppender
explicitly. See also next item.
Long lived applications which create/destroy many
SocketAppender
instances should be aware of this
garbage collection problem. Most other applications can safely
ignore it.
- If the JVM hosting the
SocketAppender
exits
before the SocketAppender
is 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()
the SocketAppender
either explicitly or by
calling the LogManager.shutdown()
method
before exiting the application.
void | activateOptions() - Connect to the specified RemoteHost and Port.
|
void | append(LoggingEvent event) - Subclasses of
AppenderSkeleton should implement this
method to perform actual logging.
|
void | cleanUp() - Drop the connection to the remote host and release the underlying
connector thread if it has been created
|
void | close() - Close this appender.
|
boolean | getLocationInfo() - Returns value of the LocationInfo option.
|
int | getPort() - Returns value of the Port option.
|
int | getReconnectionDelay() - Returns value of the ReconnectionDelay option.
|
String | getRemoteHost() - Returns value of the RemoteHost option.
|
boolean | requiresLayout() - The SocketAppender does not use a layout.
|
void | setLocationInfo(boolean locationInfo) - The LocationInfo option takes a boolean value.
|
void | setPort(int port) - The Port option takes a positive integer representing
the port where the server is waiting for connections.
|
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.
|
void | setRemoteHost(String host) - The RemoteHost option takes a string value which should be
the host name of the server where a
SocketNode is
running.
|
activateOptions , addFilter , append , clearFilters , doAppend , finalize , getErrorHandler , getFilter , getFirstFilter , getLayout , getName , getThreshold , isAsSevereAsThreshold , setErrorHandler , setLayout , setName , setThreshold |
SocketAppender
public SocketAppender()
SocketAppender
public SocketAppender(InetAddress address,
int port)
Connects to remote server at address
and port
.
SocketAppender
public SocketAppender(String host,
int port)
Connects to remote server at host
and port
.
cleanUp
public void cleanUp()
Drop the connection to the remote host and release the underlying
connector thread if it has been created
close
public void close()
Close this appender.
This will mark the appender as closed and call then
cleanUp()
method.
- close in interface Appender
getLocationInfo
public boolean getLocationInfo()
Returns value of the LocationInfo option.
getPort
public int getPort()
Returns value of the Port option.
getReconnectionDelay
public int getReconnectionDelay()
Returns value of the ReconnectionDelay option.
getRemoteHost
public String getRemoteHost()
Returns value of the RemoteHost option.
requiresLayout
public boolean requiresLayout()
The SocketAppender does not use a layout. Hence, this method
returns false
.
- requiresLayout in interface Appender
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.
setPort
public void setPort(int port)
The Port option takes a positive integer representing
the port where the server is waiting for connections.
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.
setRemoteHost
public void setRemoteHost(String host)
The
RemoteHost option takes a string value which should be
the host name of the server where a
SocketNode
is
running.
Copyright 2000-2005 Apache Software Foundation.