[logback-dev] LoggingEventVO and serialization

[Ralph Goers]

I am going to be creating a logging service. The architecture in our  
POC is the client uses  the JMSTopicAppender writing to ActiveMQ and  
then the service will listen on the topic and write to the  
destination. To avoid having the messages be logback specific so that  
our legacy system can also interact with this I will be serializing  
the messages according the the IETFSyslogLayout in my fork of Logback  
(i.e. all the messages will comply with RFC 5424). I got this working  
today with the output temporarily going to syslog-ng (which supports  
IETF syslog messages). Of Course, JMSTopicAppender and  
JMSQueueAppender had to be modified to allow a different form of  
serialization. This was easily done by just seeing if a layout was  
configured. If so, then LayoutPreSerializationTransformer is used  
instead of LoggingEventPreSerializationTransformer.

However, just for fun I tried serializing to LoggingEventVO using the  
default mechanisms in place and sending that through the JMS Appender  
to the JMSTopicSink. It didn't quite work correctly. In looking at why  
I discovered the LoggingEventVO serializes arguments by calling  
toString(). So when the JMSAppender transforms the objects their  
object type is lost. This means on the remote side it is impossible to  
convert them back to the original object. I would think that some form  
of the Serialized object should be in the argument array instead of  
just a String. Otherwise it is impossible to get the remote side to  
behave like the original client.

Ralph