Enterprise Library 6 - dynamically change log file name

Question

Is it possible to dynamically set log folder and file name in C# which overrides the config value(file name) in the Listeners section of logging configuration? Tried to follow the below link but it is applicable only for EL 5 Log messages going to previously created log file

This is how i Initialize EL Logging:

 IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
        LogWriterFactory logWriterFactory = new LogWriterFactory(configurationSource);
        Logger.SetLogWriter(logWriterFactory.Create(), false);

        ExceptionPolicyFactory factory = new ExceptionPolicyFactory(configurationSource);
        ExceptionPolicy.SetExceptionManager(factory.CreateManager());           

These are my web.config entries inside the listeners tag:

 <add name="RollingFlatFileTraceLog" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.RollingFlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.RollingFlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    fileName="C:\logs\Trace.log" footer=""
    formatter="CustomRollingFlatFileLogFormatter"
    header="" rollFileExistsBehavior="Overwrite" rollInterval="Day"
    rollSizeKB="2048" maxArchivedFiles="52" />
  <add name="RollingFlatFileErrorLog" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.RollingFlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.RollingFlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
    fileName="C:\logs\Error.log" footer="----------------------------------------"
    formatter=" CustomRollingFlatFileLogFormatter "
    header="----------------------------------------" rollFileExistsBehavior="Overwrite"
    rollInterval="Day" rollSizeKB="2048" maxArchivedFiles="52" />

I use Logger.Write and ExceptionPolicy.HandleException to write to the corresponding trace and error logs.

Answer 1

The best (and easiest!) approach would be to use programmatic configuration to set the filename.

However, you can use a similar approach to modify settings at runtime. Setup the configuration in an external file and use a file configuration source in app/web.config. An external file is necessary to avoid a configuration is read-only exception.

<?xml version="1.0" encoding="utf-8"?>
<configuration>
    <configSections>
        <section name="enterpriseLibrary.ConfigurationSource" type="Microsoft.Practices.EnterpriseLibrary.Common.Configuration.ConfigurationSourceSection, Microsoft.Practices.EnterpriseLibrary.Common, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />
    </configSections>
    <enterpriseLibrary.ConfigurationSource selectedSource="File-based Configuration Source">
        <sources>
            <add name="File-based Configuration Source" type="Microsoft.Practices.EnterpriseLibrary.Common.Configuration.FileConfigurationSource, Microsoft.Practices.EnterpriseLibrary.Common, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                filePath="entlib.config" />
        </sources>
    </enterpriseLibrary.ConfigurationSource>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6"/>
    </startup>
</configuration>

And configure the external file (entlib.config in this case):

<configuration>
    <configSections>
        <section name="exceptionHandling" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Configuration.ExceptionHandlingSettings, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />
        <section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />
    </configSections>
    <exceptionHandling>
        <exceptionPolicies>
            <add name="Policy">
                <exceptionTypes>
                    <add name="All Exceptions" type="System.Exception, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
                        postHandlingAction="NotifyRethrow">
                        <exceptionHandlers>
                            <add name="Logging Exception Handler" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging.LoggingExceptionHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                                logCategory="General" eventId="100" severity="Error" title="Enterprise Library Exception Handling"
                                formatterType="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.TextExceptionFormatter, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling"
                                priority="0" />
                        </exceptionHandlers>
                    </add>
                </exceptionTypes>
            </add>
        </exceptionPolicies>
    </exceptionHandling>
    <loggingConfiguration name="" tracingEnabled="true" defaultCategory="General">
        <listeners>
            <add name="Event Log Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                source="Enterprise Library Logging" formatter="Text Formatter"
                log="" machineName="." traceOutputOptions="None" />
            <add name="Flat File Trace Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                fileName="trace.log" />
        </listeners>
        <formatters>
            <add type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
                template="Timestamp: {timestamp}{newline}&#xA;Message: {message}{newline}&#xA;Category: {category}{newline}&#xA;Priority: {priority}{newline}&#xA;EventId: {eventid}{newline}&#xA;Severity: {severity}{newline}&#xA;Title:{title}{newline}&#xA;Machine: {localMachine}{newline}&#xA;App Domain: {localAppDomain}{newline}&#xA;ProcessId: {localProcessId}{newline}&#xA;Process Name: {localProcessName}{newline}&#xA;Thread Name: {threadName}{newline}&#xA;Win32 ThreadId:{win32ThreadId}{newline}&#xA;Extended Properties: {dictionary({key} - {value}{newline})}"
                name="Text Formatter" />
        </formatters>
        <categorySources>
            <add switchValue="All" name="General">
                <listeners>
                    <add name="Flat File Trace Listener" />
                </listeners>
            </add>
        </categorySources>
        <specialSources>
            <allEvents switchValue="All" name="All Events" />
            <notProcessed switchValue="All" name="Unprocessed Category" />
            <errors switchValue="All" name="Logging Errors &amp; Warnings">
                <listeners>
                    <add name="Event Log Listener" />
                </listeners>
            </errors>
        </specialSources>
    </loggingConfiguration>
</configuration>

Use the SerializableConfigurationSource from the blog posting:

public class SerializableConfigurationSource : IConfigurationSource
{
    Dictionary<string, ConfigurationSection> sections = new Dictionary<string, ConfigurationSection>();

    public SerializableConfigurationSource()
    {
    }

    public ConfigurationSection GetSection(string sectionName)
    {
        ConfigurationSection configSection;

        if (sections.TryGetValue(sectionName, out configSection))
        {
            SerializableConfigurationSection section = configSection as SerializableConfigurationSection;

            if (section != null)
            {
                using (StringWriter xml = new StringWriter())
                using (XmlWriter xmlwriter = System.Xml.XmlWriter.Create(xml))
                {
                    section.WriteXml(xmlwriter);
                    xmlwriter.Flush();

                    MethodInfo methodInfo = section.GetType().GetMethod("DeserializeSection", BindingFlags.NonPublic | BindingFlags.Instance);
                    methodInfo.Invoke(section, new object[] { XDocument.Parse(xml.ToString()).CreateReader() });

                    return configSection;
                }
            }
        }

        return null;
    }

    public void Add(string sectionName, ConfigurationSection configurationSection)
    {
        sections[sectionName] = configurationSection;
    }

    public void AddSectionChangeHandler(string sectionName, ConfigurationChangedEventHandler handler)
    {
        throw new NotImplementedException();
    }

    public void Remove(string sectionName)
    {
        sections.Remove(sectionName);
    }

    public void RemoveSectionChangeHandler(string sectionName, ConfigurationChangedEventHandler handler)
    {
        throw new NotImplementedException();
    }

    public event EventHandler<ConfigurationSourceChangedEventArgs> SourceChanged;

    public void Dispose()
    {
    }
}

Bootstrap the blocks at startup:

IConfigurationSource configSource = ConfigurationSourceFactory.Create();

var loggingSettings = configSource.GetSection(LoggingSettings.SectionName) as LoggingSettings;    
var data = loggingSettings.TraceListeners.First(t => t.Name == "Flat File Trace Listener") as FlatFileTraceListenerData;
// Change the file name
data.FileName = "trace_1.txt";

var loggingXmlConfigSource = new SerializableConfigurationSource();
loggingXmlConfigSource.Add(LoggingSettings.SectionName, loggingSettings);

var logFactory = new LogWriterFactory(loggingXmlConfigSource);
Logger.SetLogWriter(logFactory.Create());

IConfigurationSource config = ConfigurationSourceFactory.Create();
ExceptionPolicyFactory factory = new ExceptionPolicyFactory(config);

ExceptionManager exManager = factory.CreateManager();
ExceptionPolicy.SetExceptionManager(exManager);

// This will log to the file trace_1.txt
ExceptionPolicy.HandleException(new Exception(), "Policy");

Answer 2

As you have mentioned in the post, Setup the configuration in an external file. External file means, can you confirm in which path we have to place the Entlib.config file.