答案是Workflow Trace.
在应用程序的configuration文件中添加下面的代码, 这样Workflow相关的信息就会写在日志中了.
<configuration>
<system.diagnostics>
<switches>
<add name="System.Workflow LogToTraceListeners" value="1" />
<add name="System.Workflow.Runtime" value="All" />
<add name="System.Workflow.Runtime.Hosting" value="All" />
<add name="System.Workflow.Runtime.Tracking" value="All" />
<add name="System.Workflow.Activities" value="All" />
<add name="System.Workflow.Activities.Rules" value="All" />
</switches>
<trace autoflush="true" indentsize="4">
<listeners>
<add name="customListener"
type="System.Diagnostics.TextWriterTraceListener"
initializeData="WFTrace.log" />
</listeners>
</trace>
</system.diagnostics>
</configuration>
参考资料
=========================
WORKFLOW TRACE
http://blogs.msdn.com/b/madhuponduru/archive/2008/01/17/workflow-trace.aspx
How to enable logging information for several Windows Workflow Foundation namespaces
http://support.microsoft.com/kb/972914
Workflow Configuration Files
http://msdn.microsoft.com/en-us/library/ms732240.aspx