Change switchvalue on trace listener in runtime

Hi Is it possible to change what levels of TraceEventType that a trace listener should log without restarting the WCF service? I'm letting the user configure what the trace shou开发者_如何学JAVAld log, sends it to the service and then writes it to the config file. This solution requires the service to be restarted before the change takes effect...

Best Daniel

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It was easier than I thought. I keep track of the TraceSources and set their switchlevel when the user wants it to change.

private static void SetLogLevel(TraceSource traceSource, LogLevel logLevel)
    {
        switch (logLevel)
        {
            case LogLevel.Verbose:
                traceSource.Switch.Level = SourceLevels.Verbose;
                break;
            case LogLevel.Information:
                traceSource.Switch.Level = SourceLevels.Information;
                break;
            case LogLevel.Warning:
                traceSource.Switch.Level = SourceLevels.Warning;
                break;
            case LogLevel.Error:
                traceSource.Switch.Level = SourceLevels.Error;
                break;
            case LogLevel.Critical:
                traceSource.Switch.Level = SourceLevels.Critical;
                break;
            default:
                throw new ArgumentOutOfRangeException("logLevel");
        }
    }

I also write in the config file so the tracesource will get the same switchlevel next time the service is started.

public TraceSourceConfiguration SetLogConfiguration(TraceSourceConfiguration traceSourceConfiguration)
{
    lock (_lock)
    {
        Configuration appConfig = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
        ConfigurationSection configurationSection = appConfig.GetSection(ConfigurationSectionName);
        PropertyInformation traceSourceSection =
            configurationSection.ElementInformation.Properties[TraceSourcesSectionName];
        if (traceSourceSection != null)
        {
            ConfigurationElementCollection traceSources =
                (ConfigurationElementCollection)traceSourceSection.Value;
            foreach (ConfigurationElement traceSource in traceSources)
            {
                string name = (string)traceSource.ElementInformation.Properties[LogLevelNameElementName].Value;
                if (traceSourceConfiguration.Name == name)
                {
                    traceSource.ElementInformation.Properties[LogLevelValueElementName].Value =
                        traceSourceConfiguration.SwitchValue;
                    appConfig.Save();
                    ConfigurationManager.RefreshSection(ConfigurationSectionName);
                    TraceSourceHandler.SetTraceSourceSwitchLevel(traceSourceConfiguration.Name, traceSourceConfiguration.SwitchValue);
                    return traceSourceConfiguration;
                }

            }
        }
        return null;
    }
}

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As far as I know that is not possible. But if your service uses the PerCall InstanceContextMode, you should have minimal impact on users during the restart.

Having a fail-over service or a load-balancer would make the down-time invisible to the users.

By the way, I think the trace should not be modified by a remote call but should only be locally accessible to administrators for security reasons.