# Author Bootstrapper Application for a Bundle

Every bundle requires a bootstrapper application to drive the Burn engine. The <BootstrapperApplication> element is used to define a new bootstrapper application. The <BootstrapperApplicationRef> element is used to refer to a bootstrapper application that exists in a <Fragment> or WiX extension.

The WiX Standard Bootstrapper Application exists in the WixBalExtension.dll. The following shows how to use it in a bundle:

    <?xml version="1.0"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
<Bundle>
<Chain>
</Chain>
</Bundle>
</Wix>

The WiX Standard Bootstrapper Application may not provide all functionality a specialized bundle requires so a custom bootstrapper application DLL may be developed. The following example creates a bootstrapper application using a fictional "ba.dll":

    <?xml version="1.0"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
<Bundle>
<BootstrapperApplication SourceFile="path\to\ba.dll" />
<Chain>
</Chain>
</Bundle>
</Wix>

Inside the <BootstrapperApplication> element and <BootstrapperApplicationRef> element, you may add additional payload files such as resources files that are required by the bootstrapper application DLL as follows:

    <?xml version="1.0"?>
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
<Bundle>
<BootstrapperApplication SourceFile="path\to\ba.dll">
</Wix>