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From "Nicko Cadell" <ni...@neoworks.com>
Subject RE: Appenders and AppDomains
Date Fri, 14 Jul 2006 13:59:42 GMT
AppDomains are logical isolation units akin to lightweight processes.
log4net cannot exist outside an AppDomain because nothing can exist
outside an AppDomain. log4net must be configured in each AppDomain, and
it know nothing about the appenders or configuration in the other
AppDomains. Each AppDomain will have its own logger hierarchy and root

It is quite a challenge to find all the AppDomains in the process and
hook them up.

There are 2 different approaches that I can think of:

1) Create a MarshalByRef appender implementation, i.e. a class that
extends MarshalByRefObject and implements the IAppender interface. This
could just be a simple wrapper that forwards the call to another
IAppender, allowing you to reuse the existing appenders. 
This appender and the MarshalByRef appender wrapper would need to be
created in only 1 AppDomain. You would then need to get a reference to
this wrapper via remoting into each of the other AppDomains and then
attach that appender reference to the root logger in that AppDomain.

2) The other approach is similar in that it still requires remoting, but
rather than marshalling the appender across and attaching it to the
logger hierarchy in all the AppDomains, the events logged in the
AppDomains are sent via remoting to a single published listener which
re-logs the event it its AppDomain. This allows the logging events to be
centralised in a single AppDomain, but they can still be logged in their
own AppDomains.
To do this you will need to use the RemotingAppender in each of your
AppDomains. The RemotingAppender will sent the LoggingEvent via .NET
remoting to a published listener. The RemoteLoggingServerPlugin is a
built-in way of publishing a listener. See the Remoting examples in the
log4net download, examples\net\1.0\Remoting. In your case rather than
running separate processes, one of your AppDomains will be the server
(and receive logging events) and all the other AppDomains will be the


> -----Original Message-----
> From: Morten Andersen [mailto:morten@vianett.no] 
> Sent: 14 July 2006 14:30
> To: Log4NET User
> Subject: Appenders and AppDomains
> Hi
> Is it possible to have one appender for all app domains in a process? 
> Each app domain has its own appender, but I also want a 
> global appender for all domains.
> - Morten

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