title: How to check in WiX, if IIS-Feature is installed?
body: <p>I have programmed a Bootstrapper-project with WiX 3.8, in which i'm installing IIS Express 8.0 and activating some IIS-Features.
  The activation lies in a seperate WXS-file - including a lot of ExePackages - like that:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;Wix xmlns="http://schemas.microsoft.com/wix/2006/wi"&gt;
  &lt;Fragment&gt;
    &lt;PackageGroup Id='ActivateIisFeatures'&gt;
      &lt;ExePackage Id='IIS_WebserverRole'
                  DisplayName='Installing IIS: IIS-WebServerRole'
                  PerMachine='yes'
                  SourceFile='.\Resources\Dism.exe'
                  InstallCommand='/Online /Enable-Feature /FeatureName:IIS-WebServerRole'&gt;
      &lt;/ExePackage&gt;
      ...
    &lt;/PackageGroup&gt;
    ...
  &lt;/Fragment&gt;
  &lt;/Wix&gt;
  </code></pre>
  
  <p>Now my problem is, that by this way, the ExePackages will be installed and the features activated everytime, the setup is installed or repaired.
  So i tried the DetectCondition-Property.
  You know, if the DetectCondition returns false, the Bootstrapper plans to install the ExePackage.
  But the following edit does still install the ExePackages everytime, even when the features are active.
      
      </p>
  
  <p>What have i to do, that the IIS-features will only installed/activated, when they are not active?</p>
  
  <p>Thanks in advance!</p>