Is there a way in Log4Net or NLog (or some other logger) to output logs in an execution-stack-nested XML or JSON format?

问题

Is there a way in Log4Net or NLog (or some other logger) to output logs in an execution-stack-nested XML or JSON format, such that if function A() calls B(7) that calls C("something"), it'll output something like:

<Method name="A">
    <Method name="B" params="(int) 7">
        <Method name="C" params="(string) 'something'"/>
    </Method>
</Method>

or even better:

<Method name="A">
    <Method name="B" params="(int) 7">
        <Params>
            <int>7</int>
        </Params>
        <Method name="C">
            <Params>
                <string>something</string>
            </Params>
        </Method>
    </Method>
</Method>

Why? so I'd be able to use (e.g.) XML Notepad or some JSON-viewer (don't know of any remarkable one...) to quickly fold (irrelevant) or unfold (relevant) sub-calls when trying to understand what went wrong. I use PostSharp to log (currently using mere indentation) every method entry/exit and exceptions

回答1:

The logging framework doesn't have info about your method boundaries, and so it cannot format the XML appropriately. You can try to extend the framework and pass the additional info into the logging methods.

The easier way to get this output though is to perform all the message formatting in your aspect class and configure the logging framework to output only the message text without any other info.

For example, in log4net configuration:

<layout type="log4net.Layout.PatternLayout">
  <conversionPattern value="%message%newline" />
</layout>

In your aspect's OnEntry method you would open the XML tag (or JSON object), and in the OnExit method close the tag. You can start with the simple example below and optimize the code for your particular case (e.g. initialize the logger instance and formatting strings in RuntimeInitialize, CompileTimeInitialize methods).

[Serializable]
public class XmlLogAttribute : OnMethodBoundaryAspect
{
    public override void OnEntry(MethodExecutionArgs args)
    {
        ILog log = LogManager.GetLogger(args.Method.DeclaringType);
        if (log.IsDebugEnabled)
        {
            log.DebugFormat("<Method name=\"{0}\">", args.Method.Name);
            log.Debug("<Params>");
            foreach (object methodArgument in args.Arguments)
            {
                if (methodArgument == null)
                {
                    log.Debug("<null/>");
                }
                else
                {
                    log.DebugFormat("<{0}>{1}</{0}>", methodArgument.GetType(), methodArgument);
                }
            }
            log.Debug("</Params>");
        }
    }

    public override void OnExit(MethodExecutionArgs args)
    {
        ILog log = LogManager.GetLogger(args.Method.DeclaringType);
        log.Debug("</Method>");
    }
}

回答2:

You would have to create your own override of the XmlLayoutBase FormatXml method in log4net.

See a similar answer here

回答3:

See stacktrace of log4net PatternLayout. It is obviously expensive to harvest, but should give some results. It is also possible to change the rendering of the log information. In the log4net.Ext.Json project, there's a decorator that could be used to that effect. (I'm the author).

来源：https://stackoverflow.com/questions/20730298/is-there-a-way-in-log4net-or-nlog-or-some-other-logger-to-output-logs-in-an-ex

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