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From Ceki Gulcu <c...@qos.ch>
Subject RE: Question about the properties file. Please Help.
Date Fri, 16 Nov 2001 16:38:01 GMT

Hello,

Anyone interested in adding version support for LoggingEvent serialization? Currently, the
sending side and the receiving side of a LoggingEvent have to have the same fields. If a field
is added or if a field is removed in LoggingEvent from one log4j version to the next, if the
log4j versions do not match, then serialization does not work.   

It would be useful if we could gracefully handle *some* changes in LoggingEvent. This is quite
a nice software engineering problem. Regards, Ceki 

At 10:02 16.11.2001 -0600, qding@csc.com wrote:
>Scott:
>
>After I cleaned up log4j version on both send and receive sides, the
>problem automatically disappears.    Obviously, the difference of log4j
>versions causes the server side classloader failure of loading log4j.  I
>actually packaged the log4j and my publisher into an EJB. Thank you for
>your advice very much.
>
>Qin
>
>
>                                                                                     
                                 
>                    Scott Coleman                                                    
                                 
>                    <scott.coleman@so        To:     'Log4J Developers List' <log4j-dev@jakarta.apache.org>
           
>                    ltima.com>               cc:                                  
                                    
>                                             Subject:     RE: Question about the properties
file. Please Help.         
>                    11/15/01 01:49 AM                                                
                                 
>                    Please respond to                                                
                                 
>                    Log4J Developers                                                 
                                 
>                    List                                                             
                                 
>                                                                                     
                                 
>                                                                                     
                                 
>
>
>
>
>I would have thought that point 2, below is the problem.
>You can TEST this by putting log4j.jar in the classpath of weblogic, by
>modifying the start script. Then every ejb will be able to load log4j
>classes.  is that you do not have log4j.jar in the classpath of weblogic.
>If
>this works then you need to decide whether you wish to have hot deploy
>functionality of log4j, is you do you must package it (i think) with your
>ejb.
>
>Regards
>Scott
>
>-----Original Message-----
>From: Ceki Gulcu [mailto:ceki@qos.ch]
>Sent: Wednesday, November 14, 2001 11:51 PM
>To: Log4J Developers List
>Subject: Re: Question about the properties file. Please Help.
>
>
>
>Hello,
>
>LoggingEvent is serializable. It has been seralizable and serialized for a
>long time.
>There are two possible reasons for your problem:
>
>1) You are not using the same log4j version on sender side and the MDB
>side.
>
>2) log4j.jar and consequently org.apache.log4j.spi.LoggingEvent is not
>accessible by your MDB.
>
>Hope this helps, Ceki
>
>At 16:14 14.11.2001 -0600, you wrote:
>>Hi, Ceki:
>>
>>I wrap the  log4j  into an EJB and config it  to use JMSAppender to
>publish
>>logging message to the JMS server on Weblogic 6.1.  And I wrote a
>>MessageDrivenBean (MDB) to consume the message by writing the msg to our
>>database.
>>
>>When the JMS server receives Message with ObjectMessage in it, it delivers
>>the Message to my MDB by calling the MDB's onMessage method. When I tried
>>to retrieve the the LoggingEvent from the ObjectMessage, I receive an
>error
>>message stating "Error: deserializing object".
>>
>>This is what I try to do:
>>
>>try {
>>  ObjectMessage om = (ObjectMessage)message;       ------------ successful
>>  LoggingEvent msg = (LoggingEvent) om.getObject();  ------------ failed
>>  String strTokens = (String) msg.getMessage();              -------------
>>never get in here
>>}
>>catch(JMSException jmse)
>>{
>>  jmse.printStackTrace();
>>}
>>
>>I checked the MDB spec, that ObjectMessage's getObject() returns
>>java.io.Serializable. LogggingEvent is Serializable class.  I don't know
>>why it can't be casted to LoggingEvent.
>>
>>I wonder is it because LoggingEvent constructor carries a param message
>>which is the type of Object.  Object itself is not Serializable. Also, an
>>instance variable of LoggingEvent is transient Object message. So, this
>>message cannot be serialized due to the key word trancient.  getMessage()
>>method returns Object message instead of Serializable.  Do you think these
>>may cause the deserialization problem I have experienced?  If yes, how can
>>I work around this?  If I change Object to Serializable, then I have to
>>change not only LoggingEvent class but Category class as well?  Please
>>advise. Thank you very much.
>>
>>Qin
>>
>>
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