org.apache.log4j.net
Class SocketHubAppender
- Appender, OptionHandler
public class SocketHubAppender
Sends
LoggingEvent
objects to a set of remote log servers,
usually a
SocketNodes
.
Acts just like
SocketAppender
except that instead of
connecting to a given remote log server,
SocketHubAppender
accepts connections from the remote
log servers as clients. It can accept more than one connection.
When a log event is received, the event is sent to the set of
currently connected remote log servers. Implemented this way it does
not require any update to the configuration file to send data to
another remote log server. The remote log server simply connects to
the host and port the
SocketHubAppender
is running on.
The
SocketHubAppender
does not store events such
that the remote side will events that arrived after the
establishment of its connection. Once connected, events arrive in
order as guaranteed by the TCP protocol.
This implementation borrows heavily from the
SocketAppender
.
The SocketHubAppender has the following characteristics:
- If sent to a
SocketNode
, 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.
SocketHubAppender
does not use a layout. It
ships a serialized LoggingEvent
object to the remote side.
SocketHubAppender
relies on the TCP
protocol. Consequently, if the remote side is reachable, then log
events will eventually arrive at remote client.
- If no remote clients are attached, the logging requests are
simply dropped.
- Logging events are automatically buffered by the
native TCP implementation. This means that if the link to remote
client is slow but still faster than the rate of (log) event
production, the application will not be affected by the slow network
connection. However, if the network connection is slower then the
rate of event production, then the local application can only
progress at the network rate. In particular, if the network link to
the the remote client is down, the application will be blocked.
On the other hand, if the network link is up, but the remote
client is down, the client will not be blocked when making log
requests but the log events will be lost due to client
unavailability.
The single remote client case extends to multiple clients
connections. The rate of logging will be determined by the slowest
link.
- If the JVM hosting the
SocketHubAppender
exits
before the SocketHubAppender
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 SocketHubAppender
either explicitly or by calling
the LogManager.shutdown()
method before
exiting the application.
void | activateOptions() - Set up the socket server on the specified port.
|
void | append(LoggingEvent event) - Append an event to all of current connections.
|
void | cleanUp() - Release the underlying ServerMonitor thread, and drop the connections
to all connected remote servers.
|
void | close() - Close this appender.
|
boolean | getLocationInfo() - Returns value of the LocationInfo option.
|
int | getPort() - Returns value of the Port option.
|
boolean | requiresLayout() - The SocketHubAppender 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.
|
activateOptions , addFilter , append , clearFilters , doAppend , finalize , getErrorHandler , getFilter , getFirstFilter , getLayout , getName , getThreshold , isAsSevereAsThreshold , setErrorHandler , setLayout , setName , setThreshold |
SocketHubAppender
public SocketHubAppender()
SocketHubAppender
public SocketHubAppender(int _port)
Connects to remote server at address
and port
.
cleanUp
public void cleanUp()
Release the underlying ServerMonitor thread, and drop the connections
to all connected remote servers.
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.
requiresLayout
public boolean requiresLayout()
The SocketHubAppender 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.
Copyright 2000-2005 Apache Software Foundation.