How can I use log4net in WF4? - log4net

Question

I've created a simple WF4 console app and set up log4net identically to my other apps. However, when I fire up the console and use the ILog object inside WF4 (I actually pass it into the workflow), no information is presented using my ColoredConsoleAppender. What am I doing wrong?

Answer 1

Workflow trace output is written to trace listeners and as far as I am aware log4net doesn't log the output written to a trace listener by default. I am no expert on log4net so there might be an easier way but creating a TraceListener that just passes all data on to log4net is not hard, the following code worked just fine in a quick test.
public class Log4netTraceListener : TraceListener
{
private static readonly ILog _log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, params object[] data)
{
base.TraceData(eventCache, source, eventType, id, data);
}
public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, object data)
{
var logger = LogManager.GetLogger(source);
switch (eventType)
{
case TraceEventType.Critical:
logger.Fatal(data);
break;
case TraceEventType.Error:
logger.Error(data);
break;
case TraceEventType.Information:
logger.Info(data);
break;
case TraceEventType.Verbose:
logger.Debug(data);
break;
case TraceEventType.Warning:
logger.Warn(data);
break;
default:
base.TraceData(eventCache, source, eventType, id, data);
break;
}
}
public override void Write(string message)
{
_log.Info(message);
}
public override void WriteLine(string message)
{
_log.Info(message);
}
Next you need to make sure the activity trace information is send to this TraceListener using the following code in you app.config.
<system.diagnostics>
<sources>
<source name="System.Activities"
switchValue="Verbose">
<listeners>
<add name="Test"
type="WorkflowConsoleApplication17.Log4netTraceListener, WorkflowConsoleApplication17"/>
</listeners>
</source>
</sources>
</system.diagnostics>

Answer 2

Create an Extension for your workflow that your activities can get from the context.
var wf = new WorkflowApplication(myActivity);
var log = new MyLogForNetExtensionLol();
wf.Extensions.Add(log);
then, within the activity:
var log = context.GetExtension<ILog>();
log.Write("Worked!");