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Date: Tue, 3 Oct 2006 02:09:15 -0700 (PDT)
From: patrick <Patrick.Wyss@mobilesolutions.ch>
To: log4j-dev@logging.apache.org
Subject: Re: Enhanced FileAppender
In-Reply-To: <3FE38194C8A3334A959B64B7D9A1E27B6E3185@plejaden.seychelles.ergo>
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References: <3FE38194C8A3334A959B64B7D9A1E27B6E3185@plejaden.seychelles.ergo>


hi heri,

i like the idea a lot.
however (admittedly without thinking to much about it ;-} ) i'd use
"Strategy pattern" http://www.dofactory.com/Patterns/PatternStrategy.aspx

and something like:
FileNameBuilder {
 public String buildFilename( LoggingEvent event );
}

maybe it would be an idea to add a method
 public boolean closeFileAfter( LoggingEvent event );

to make it possible to close the files with a specific log event.

but that's just some quick toughts ;-}

best regards
patrick


Bender Heri wrote:
> 
> Hello all
> 
> Since in user list nobody commented my suggestion for an enhancement of
> the FileAppender I will repeat it here.
> 
> Problem:
> A often asked issue in user list is the problem to separate log files
> dependent on different criterias, like a client-ID in a server
> environment, a mandant- or task-ID in scheduler applications, etc.
> Although it is possible to achieve this with the existing log4j framework
> all possible solutions are quite complex  or have other drawbacks (own
> repository selector, working with different classloaders, subclass
> concrete descendents of FileAppender).
> 
> Solution:
> The FileAppender is supplied with a property of type FileNameBuilder
> (Design pattern: visitor). The user-supplied implementation of this
> Interface can build a filename based on whatever criterias (i.e. MDC,
> global Environment, etc.). The visitor is called each time a Fileappender
> wants to append a log message. The FileAppender holds a collection of file
> writers for each separate file name delivered by FileNameBuilder.
> To avoid the excess of open file handles the FileAppender could watch the
> logging activity to one particular file. If the file was not accessed
> after let's say one hour it could be closed (this timeout could also be
> configurable). Special care must be done if the property "append" of the
> FileAppender is false. If the file was closed because the above timeout
> had elapsed and then reopened later again, the file shouldn't be
> overridden.
> If the config file does not specify a FileNameBuilder a default
> implementation would be used which returns always the configured filename.
> This wouldn't break existing code. The existing property fileName would
> remain and hold always the configured filename.
> 
> The interface of the FileNameBuilder would be like this:
> 
> public String buildFilename( FileAppender aFileAppender );
> 
> 
> Any comments on this?
> 
> 
> Heri
> 
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