Convert XAP to CAB

A legacy Windows deployment or archival workflow may require a CAB file when it cannot accept a Silverlight or Windows Phone XAP package. Repacking is useful only when the receiving tool needs the files as an archive; it does not make the application installable on a different platform.

What the XAP format is

XAP is a ZIP-based package used for Microsoft Silverlight applications and legacy Windows Phone apps. It typically contains assemblies, resources, and a manifest; Silverlight SDK and Visual Studio workflows produced these files for application deployment.

What the CAB format is

Microsoft Cabinet (CAB) is an archive format used by Windows software distribution and installers. It can store multiple files with compression such as MSZIP or LZX. A CAB archive is not itself a Silverlight or Windows Phone application package.

How to create a CAB archive

1. Open the XAP in 7-Zip and extract its contents to a working folder. Include all files required by the receiving workflow, not just the manifest and main assembly.
2. Create a Diamond Directive File (DDF) for Windows makecab. List each file to include, followed by its desired name inside the CAB. For example, save as C:\work\files.ddf and adjust the file list and paths:

   .Set CabinetNameTemplate=output.cab
   .Set DiskDirectoryTemplate=.
   .Set Cabinet=on
   .Set Compress=on
   .Set CompressionType=MSZIP
   "C:\work\unpacked\AppManifest.xaml" "AppManifest.xaml"
   "C:\work\unpacked\MyApp.dll" "MyApp.dll"

   This short example includes only two files; add every required file and use the internal names or paths expected by the receiving tool.
3. Open Command Prompt in the folder where you want the CAB written and run makecab /F C:\work\files.ddf. The example writes output.cab to the current folder. Windows generally includes makecab; if it is missing, install Windows cabinet tools from a Windows SDK.
4. Open the resulting CAB with 7-Zip or extract it with a cabinet utility to verify its contents and internal paths.

7-Zip extracts the XAP; makecab creates the CAB. Online conversion is unnecessary for this repackaging task and can expose proprietary application files.

Compatibility and limitations

Repacking preserves included file contents, but it does not preserve XAP deployment behavior or transfer a package signature. Software expecting a XAP will not accept the CAB. A Windows Mobile installer may require a specific CAB layout, installation metadata, or signing, so a generic archive made with makecab may not install on a device.