[logback-user] SocketAppender application property

Ceki Gulcu ceki at qos.ch
Thu Aug 20 17:16:13 CEST 2009

haukex wrote:
> Hi Ceki,
> Thanks for this information! I just tested things out and am having some
> problems.
> I added "<contextName>TestClient</contextName>" to the client's logback.xml
> and "<contextName>LoggingServer</contextName>" to the server's logback.xml.
> However, when I used %contextName in the PatternLayout on the server, I am
> seeing "LoggingServer" being output in the log file instead of "TestClient",
> so it seems this information is not serialized?

It's a bug in ContextNameConverter. Instead of reading the context name found in 
the event passed as parameter, it used the context to which it (the 
ContextNameConverter instance) is attached to. Usually, the context found in the 
event and the context the ContextNameConverter instance is attached to are the 
same. One exception occurs when the event is sent to a remote system. Anyway, I 
entered a jira issue for this: http://jira.qos.ch/browse/LBCLASSIC-149

> Also, I tried setting <property name="LOGGING_CLIENT" value="TestClient" />
> on the client (is this the right way to set LoggerContext properties?), and
> then using ${LOGGING_CLIENT} in the PatternLayout on the server, but I am
> getting "LOGGING_CLIENT_IS_UNDEFINED" output in the server log. When I set
> the same property on the server, the value is output.

There is no converter to display the value of a context parameter. However, it 
should be fairly easy to write one. Here is a possible implementation:

package apackage.of.yr.choice;

import java.util.Map;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.spi.LoggerContextVO;

public final class ContextPropertyConverter extends ClassicConverter {

   String propertyName;

   public void start() {
     String optStr = getFirstOption();
     if (optStr != null) {
       propertyName = optStr;

   public String convert(ILoggingEvent event) {
     if(propertyName == null) {
       return "ContextProperty_HAS_NO_NAME";
     } else {
       LoggerContextVO lcvo = event.getLoggerContextVO();
       Map<String, String> map = lcvo.getPropertyMap();
       return map.get(propertyName);

Since ContextPropertyConverter does not exist in the current logback release 
(0.9.17), you need to inform logback of its existence. See the
http://logback.qos.ch/manual/layouts.html and the section entitled "Creating a 
custom conversion specifier". You would need to add a conversion rule element 
similar to the following in your configuration file:

   <conversionRule conversionWord="property"
              converterClass="apackage.of.yr.choice.ContextPropertyConverter" />

I hope this helps.  By the way, you would need to add 
ContextPropertyConverter.class onto your class path.

> What am I doing wrong? :)


Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.

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