What is the best way to centralize logging with NLog?

Question

I have been assigned a project with a lot of poorly written code that is based around SharePoint.

It consists of about 15 subprojects, some of them being windows services, some web services, some web applications running inside of SharePoint, some being webparts and even console applications. They all run on the same server and call each other.

There are already many issues in production but they are hard to trace down.
The original developer must have been a fan of either Salinger or Pokémon series judging by his tireless effort to catch all exceptions. Unfortunately, none of them get reported or logged, ever.

My current task is to introduce logging into the whole project so I could find now-invisible exceptions, follow tangled recurring calls and have some stack traces at least. I decided to go with NLog, seeing it's active and cool, as opposed to log4net which is perfectly fine but somewhat not as fancy to my taste.

Because the components are tightly coupled, I want to centralize logging in one file so related errors don't get scattered across the hard drive. Therefore, I am looking to have two or three different log files with five or more projects writing to each of them more or less simultaneously.

What is the best way to configure NLog to centralize logging? Should I have a config file for each project, or should related projects share them? Where should I put config file to log from SharePoint webparts? Am I going to face any permission issues?

I'm using SharePoint 2007.

Answer 1

The easiest way to centralize is probably to simply log to a database, one benefit being that multiple applications and write to the database easier than to the same log file. For each application, configure NLog to log to the Database target, using the same Database target configuration parameters for each. Your NLog.config file might look something like this:

<?xml version="1.0" encoding="utf-8" ?>
<!-- 
  This file needs to be put in the application directory. Make sure to set 
  'Copy to Output Directory' option in Visual Studio.
  -->
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true" 
      internalLogLevel="Debug"
      internalLogFile="nlog_log.log">


  <targets async="true">
    <target name="sqlexpress" xsi:type="Database">
      <connectionString>
        Data Source=.\SQLEXPRESS;Initial Catalog=LoggingDB;Integrated Security=True;
      </connectionString>
      <commandText>
        insert into LogTable(DateTime,Logger,LogLevel,Message,ProcessId,ManagedThreadId) values (@DateTime,@Logger,@LogLevel,@Message,@ProcessId,@ManagedThreadId);
      </commandText>
      <parameter name="@DateTime" layout="${date:format=yyyy\-MM\-dd HH\:mm\:ss.fff}"/>
      <parameter name="@Logger" layout="${logger}"/>
      <parameter name="@LogLevel" layout="${level}"/>
      <parameter name="@Message" layout="${message}"/>
    </target>

    </target>
  </targets>
  <rules>
    <logger name="*" minlevel="Trace" writeTo="sqlexpress" />
  </rules>
</nlog>

You could certainly log to files in addition to (or instead of) logging to a database.

I am not familiar with doing this from SharePoint, so I can't comment on any configuration or permission issues that you might run into there.

Here is a link I found where there is a discussion of getting NLog to work in a SharePoint environment:

http://nlog-forum.1685105.n2.nabble.com/Is-anyone-using-NLog-with-SharePoint-td2171451.html

That link appears to put you at the top of the NLog forum instead of the specific post. Search for this text in the forum "Is anyone using NLog with SharePoint" and you should find the right post.

Good luck!

Answer 2

You could also just leverage the existing logging infrastructure in SharePoint and write to the ULS logs. This way your log information can be viewed in a complete context using the ULS log viewer. For SharePoint 2007 see this blog how to write to the ULS log: SharePoint Trace Logs and the Unified Logging Service (ULS)

With SharePoint 2010 it has become even easier with improvements to the SPDiagnosticsService class where you can use the new WriteTrace method.