transient Throwable object in spi.ThrowableInformation

["FLYNN, Peter -Syntegra UK" <Pe...@syntegra.com>]

Hi,

I currently have a set of servers that send out log messages over JMS, using
the JMSAppender. 
I have a Swing based Log4J Log Message Viewer which takes the messages
published to the logging topic, and
displays the relevant details.  

I noticed that when a Throwable object is included in the Log Message, a
ThrowableInformation object is created, but
when deserialised, the Throwable object is null.  After investigation, I
found that the Throwable object under the class
org.apache.log4j.spi.ThrowableInformation had declared the Throwable object
as Transient.  This would mean that
it would not be serialised.  I removed the transient call, and the Throwable
is now serialised and sent over JMS.

Is there a particular reason why it was declared transient?  Was it to keep
the object size down ( a consideration when
serialising over a network connection using JMS).  I can still obtain the
String representation of the stack trace by using the 
API method getThrowableStrRep() in org.apache.log4j.spi.LoggingEvent.

I have included the updated org.apache.log4j.spi.ThrowableInformation class.

Best regards,
Peter



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Re: transient Throwable object in spi.ThrowableInformation

[Ceki Gülcü <ce...@qos.ch>]

The reason is that the stack trace of an exception is not transmitted 
through serialization.  Hence we had to convert an exception's stack trace 
to a string array. All appenders manipulate this string array instead of 
the exception. Hope this makes sense.

At 11:48 21.01.2003 +0000, you wrote:

>Hi,
>
>I currently have a set of servers that send out log messages over JMS, 
>using the JMSAppender.
>I have a Swing based Log4J Log Message Viewer which takes the messages 
>published to the logging topic, and
>displays the relevant details.
>
>I noticed that when a Throwable object is included in the Log Message, a 
>ThrowableInformation object is created, but
>when deserialised, the Throwable object is null.  After investigation, I 
>found that the Throwable object under the class
>
>org.apache.log4j.spi.ThrowableInformation had declared the Throwable 
>object as Transient.  This would mean that
>it would not be serialised.  I removed the transient call, and the 
>Throwable is now serialised and sent over JMS.
>
>Is there a particular reason why it was declared transient?  Was it to 
>keep the object size down ( a consideration when
>serialising over a network connection using JMS).  I can still obtain the 
>String representation of the stack trace by using the
>
>API method getThrowableStrRep() in org.apache.log4j.spi.LoggingEvent.
>
>I have included the updated org.apache.log4j.spi.ThrowableInformation class.
>
>Best regards,
>Peter



--
Ceki



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