[jira] [Created] (LOG4NET-655) CONFIGURATION - Load extension assemblies by configuration reference

["Jason Newell (Jira)" <ji...@apache.org>]

Jason Newell created LOG4NET-655:
------------------------------------

             Summary: CONFIGURATION - Load extension assemblies by configuration reference
                 Key: LOG4NET-655
                 URL: https://issues.apache.org/jira/browse/LOG4NET-655
             Project: Log4net
          Issue Type: New Feature
          Components: Layouts
            Reporter: Jason Newell


h1. The problem

Currently to extend the layout the extension code needs to be in the main dll or exe as it has to be loaded at startup for log4net to be able to find the layout extension. In order to create the ability to have these extensions in an assembly which can be shared with other projects there needs to be a way to tell log4net via the configuration which assembly to load.
h2. An example of a layout extension
h3. C# Code

public class FileNamePatternConverter : PatternLayoutConverter
 {
 /// <inheritdoc />
 protected override void Convert(TextWriter clsTextWriter, LoggingEvent clsLoggingEvent)
 {
 clsTextWriter.Write(Path.GetFileName(clsLoggingEvent.LocationInformation.FileName));
 }
 }
h3. Configuration

<layout type="log4net.Layout.PatternLayout">
 <converter>
 <name value="filename" />
 <type value="X.Logging.FileNamePatternConverter" />
 </converter>
 <conversionPattern value="[%5level] %date\{dd MMM yyyy HH:mm:ss} %filename:%line %logger - %message%newline" />
 </layout>
h3. Error message

log4net:ERROR Could not create Appender [RollingFile] of type [log4net.Appender.RollingFileAppender]. Reported error follows.
System.TypeLoadException: Could not load type [X.DotNet.Logging.FileNamePatternConverter]. Tried assembly [log4net, Version=2.0.11.0, Culture=neutral, PublicKeyToken=669e0ddf0bb1aa2a] and all loaded assemblies
 at log4net.Util.SystemInfo.GetTypeFromString(Assembly relativeAssembly, String typeName, Boolean throwOnError, Boolean ignoreCase)
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement element, Object target)
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.CreateObjectFromXml(XmlElement element, Type defaultTargetType, Type typeConstraint)
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement element, Object target)
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.CreateObjectFromXml(XmlElement element, Type defaultTargetType, Type typeConstraint)
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.SetParameter(XmlElement element, Object target)
 at log4net.Repository.Hierarchy.XmlHierarchyConfigurator.ParseAppender(XmlElement appenderElement)
log4net:ERROR Appender named [RollingFile] not found.

 
h1. Proposed Solution

 {color:#172b4d}Add a line to the converter configuration to force the loading of the assembly.{color}

<layout type="log4net.Layout.PatternLayout">
 <converter>
 <name value="filename" />
 <type value="X.Logging.FileNamePatternConverter" />

*{color:#4c9aff}<assembly value="XLoggingExtensions" />{color}*
 </converter>
 <conversionPattern value="[%5level] %date\{dd MMM yyyy HH:mm:ss} %filename:%line %logger - %message%newline" />
 </layout>



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