evaluationenginelogging.html

---
layout: documentation 
title: EvaluationEngine 
teaser: Decouple business logic from control flow
navigation:
   - name: Overview
     link: evaluationengine.html
   - name: Tutorial
     link: evaluationenginetutorial.html	
   - name: Modules
     link: evaluationenginemodules.html
   - name: Hierarchical Evaluation Engines
     link: evaluationenginehierarchies.html
   - name: Aggregators
     link: evaluationengineaggregators.html
   - name: Expressions
     link: evaluationengineexpressions.html
   - name: Strategies
     link: evaluationenginestrategies.html
   - name: Validation
     link: evaluationenginevalidation.html
   - name: Logging
     link: evaluationenginelogging.html
   - name: Tips and Tricks
     link: evaluationenginetipsandtricks.html
   - name: Specifications
     link: evaluationenginespecifications.html		 
---
<h2>Logging</h2>
<p>
There exists a log4net extension that provides logging using log4net. 
Please, download the nuget package Appccelerate.SourceTemplates to get the sample code. 
You can either take the source as is, or change it so it meets your logging requirements.
</p>
<p>
You can set the log extension on the evaluation engine:
</p>
<script type="syntaxhighlighter" class="brush: csharp"><![CDATA[
evaluationEngine.SetLogExtension(new Log4Net.EvaluationEngineLogExtension());
]]></script>
<p>
This logs messages like the following:
</p>
<script type="syntaxhighlighter" class="brush: plain"><![CDATA[
INFO - Question = how cool is the evaluation engine?
Answer =  extremely super fantastic
Used strategy = aggregator strategy
Used Aggregator = expression aggregator 
    with seed '' 
	and aggregate function (aggregate, value) => ((aggregate + " ") + value)
Expressions =
    inline expression = (q, p) => "extremely" => extremely
    inline expression = (q, p) => "super" => super
    inline expression = (q, p) => "fantastic" => fantastic
]]></script>
<p>
You can see which strategy, aggregator and expressions were used. And what the individual expressions returned as results and what the answer was.
</p>