Log messages going to previously created log file

Question

I am using enterprise library 5.0 logging in my asp.net site,
My web.config file is as follows:

Answer 1

How do you define "immediately"? If you mean in the middle of the executing request then I don't think you can do that via configuration since the configuration will not be refreshed for that request.

Here's an implementation that seems to work for me based on the blog post Enterprise Library Programmatic Configuration. I don't write the config change back to disk but change it in memory instead.

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        EnterpriseLibraryContainer.Current.GetInstance<LogWriter>()
            .Write("test", "General");

        string path = "C:\\Logs\\anotherlogfile.log";
        SetLogFilePath(path);

        EnterpriseLibraryContainer.Current.GetInstance<LogWriter>()
            .Write("Another test", "General");
    }

    public void SetLogFilePath(string filePath)
    {
        ConfigurationFileMap objConfigPath = new ConfigurationFileMap();

        // App config file path.
        string appPath = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;
        objConfigPath.MachineConfigFilename = appPath;

        Configuration entLibConfig = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");

        LoggingSettings loggingSettings = (LoggingSettings)entLibConfig.GetSection(LoggingSettings.SectionName);

        TraceListenerData traceListenerData = loggingSettings.TraceListeners.Get("Flat File Trace Listener");
        FlatFileTraceListenerData objFlatFileTraceListenerData = traceListenerData as FlatFileTraceListenerData;

        objFlatFileTraceListenerData.FileName = filePath;

        IUnityContainer container = new UnityContainer();
        container.AddNewExtension<EnterpriseLibraryCoreExtension>();

        // Configurator will read Enterprise Library configuration 
        // and set up the container
        UnityContainerConfigurator configurator = new UnityContainerConfigurator(container);

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

        // Configure the container with our own custom logging
        EnterpriseLibraryContainer.ConfigureContainer(configurator, loggingXmlConfigSource);

        // Wrap in ServiceLocator
        IServiceLocator locator = new UnityServiceLocator(container);

        // Release lock(s) on existing file(s)
        EnterpriseLibraryContainer.Current.GetInstance<LogWriter>().Dispose();

        // And set Enterprise Library to use it
        EnterpriseLibraryContainer.Current = locator;
    }
}

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()
    {
    }
}