Apache log4cxx  Version 0.10.0
XMLSocketAppender Class Reference

Sends LoggingEvent objects in XML format to a remote a log server, usually a XMLSocketNode. More...

Inheritance diagram for XMLSocketAppender:
SocketAppenderSkeleton AppenderSkeleton Appender ObjectImpl OptionHandler Object Object

List of all members.

Public Member Functions

 XMLSocketAppender ()
 ~XMLSocketAppender ()
 XMLSocketAppender (helpers::InetAddressPtr address, int port)
 Connects to remote server at address and port.
 XMLSocketAppender (const LogString &host, int port)
 Connects to remote server at host and port.

Static Public Attributes

static int DEFAULT_PORT
 The default port number of remote logging server (4560).
static int DEFAULT_RECONNECTION_DELAY
 The default reconnection delay (30000 milliseconds or 30 seconds).
static const int MAX_EVENT_LEN
 An event XML stream cannot exceed 1024 bytes.

Protected Member Functions

virtual void setSocket (log4cxx::helpers::SocketPtr &socket, log4cxx::helpers::Pool &p)
virtual void cleanUp (log4cxx::helpers::Pool &p)
virtual int getDefaultDelay () const
virtual int getDefaultPort () const
void append (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &pool)
 Subclasses of AppenderSkeleton should implement this method to perform actual logging.

Detailed Description

Sends LoggingEvent objects in XML format to a remote a log server, usually a XMLSocketNode.

The XMLSocketAppender has the following properties:

  • If sent to a XMLSocketNode, 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.
  • XMLSocketAppenders use exclusively an XMLLayout. They ship an XML stream representing a 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 an XMLSocketAppender is no longer attached to any logger, it will not be destroyed in the presence of a connector thread. A connector thread exists only if the connection to the server is down. To avoid this destruction problem, you should close the the XMLSocketAppender explicitly. See also next item.

    Long lived applications which create/destroy many XMLSocketAppender instances should be aware of this destruction problem. Most other applications can safely ignore it.
  • If the application hosting the XMLSocketAppender exits before the XMLSocketAppender is closed either explicitly or subsequent to destruction, then there might be untransmitted data in the pipe which might be lost.

    To avoid lost data, it is usually sufficient to close the XMLSocketAppender either explicitly or by calling the LogManager::shutdown method before exiting the application.

Constructor & Destructor Documentation

XMLSocketAppender ( helpers::InetAddressPtr  address,
int  port 
)

Connects to remote server at address and port.

XMLSocketAppender ( const LogString host,
int  port 
)

Connects to remote server at host and port.


Member Function Documentation

void append ( const spi::LoggingEventPtr event,
log4cxx::helpers::Pool p 
) [protected, virtual]

Subclasses of AppenderSkeleton should implement this method to perform actual logging.

See also AppenderSkeleton::doAppend method.

Implements AppenderSkeleton.

virtual void cleanUp ( log4cxx::helpers::Pool p) [protected, virtual]
virtual int getDefaultDelay ( ) const [protected, virtual]
virtual int getDefaultPort ( ) const [protected, virtual]
virtual void setSocket ( log4cxx::helpers::SocketPtr &  socket,
log4cxx::helpers::Pool p 
) [protected, virtual]

Member Data Documentation

int DEFAULT_PORT [static]

The default port number of remote logging server (4560).

The default reconnection delay (30000 milliseconds or 30 seconds).

const int MAX_EVENT_LEN [static]

An event XML stream cannot exceed 1024 bytes.


The documentation for this class was generated from the following file:
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