Howto download a dependency with WIX 3.6

I'm using WIX 3.6 Bundle to install an application. It requires some prerequisites. How can I set up the package, so that the bootstrapper automatically download the file from the internet?

I know that WIX setup itself does exactly that. But I can't find the difference. Here's my fragment for the .NET Framework 3.5:

<Fragment>
    <util:RegistrySearch Root="HKLM" Key="SOFTWARE\Microsoft\Net Framework Setup\NDP\v3.5" Value="Version" Variable="NetFX35Version" />
    <util:RegistrySearch Root="HKLM" Key="SOFTWARE\Microsoft\Net Framework Setup\NDP\v3.5" Value="Version" Variable="NetFX35x64Version" Win64="yes" />
    <util:RegistrySearch Root="HKLM" Key="SOFTWARE\Microsoft\Net Framework Setup\NDP\v3.5" Value="SP" Variable="NetFX35SP" />
    <util:RegistrySearch Root="HKLM" Key="SOFTWARE\Microsoft\Net Framework Setup\NDP\v3.5" Value="SP" Variable="NetFX35x64SP" Win64="yes" />

    <PackageGroup Id="NetFX35">
      <ExePackage Id="NetFX35" Cache="no" Compressed="no" PerMachine="yes" Permanent="yes" Vital="yes" 
              SourceFile="$(var.TargetDir)dotnetfx35setup.exe"
              DownloadUrl="http://download.microsoft.com/download/0/6/1/061F001C-8752-4600-A198-53214C69B51F/dotnetfx35setup.exe"
              DetectCondition="(NetFX35Version AND NetFX35SP >= 1) AND (NOT VersionNT64 OR (NetFX35x64Version AND NetFX35x64SP >= 1))" />
    </PackageGroup>
</Fragment>

When I use this fragment and the dotnetfx35setup.exe is not present, the Bootstrapper shows a message box, asking if it should download the file. But it should do that automatically.

UPDATE:

I'm using WixStandardBootstrapperApplication. Does the managed bootstrapper applicati开发者_JAVA百科on behave different?

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WixStdBA always prompts before downloading. I'd suggest filing a feature request to make it something you can suppress. There isn't currently a managed bootstrapper application; ManagedBootstrapperApplicationHost is the infrastructure to support your own managed-code BA.