| XBAP | |
|---|---|
| Filename extension | .xbap |
| Internet media type | application/x-ms-xbap |
| Type of format | Package management system,file archive |
| Container for | Software package |
| Extended from | ZIP |
XAML Browser Applications (XBAP, pronounced "ex-bap") areWindows Presentation Foundation (.xbap) applications that were intended to run inside aweb browser such asFirefox orInternet Explorer through theNPAPI interface. Due to NPAPI being phased out in recent years[needs update], and from lack of support, there are currently no browsers that support XBAP applications.[1]
Hosted applications run in a partial trustsandbox environment and are not given full access to the computer's resources like opening a new network connection or saving a file to the computer disk and not allWPF functionality is available. The hosted environment is intended to protect the computer frommalicious applications; however it can also run in full trust mode by the client changing the permission. Starting an XBAP from anHTML page was seamless (with no security or installation prompt). Although one perceived the application running in the browser, it actually ran in an out-of-process executable (PresentationHost.exe) managed by avirtual machine.
XBAP applications have certain restrictions on what.NET features they can use. Since they run in partial trust, they are restricted to the same set of permission granted to any InternetZone application. Nearly all standard WPF functionality, however, around 99%, is available to an XBAP application. Therefore, most of the WPFUI features are available.[2]
Starting in February 2009, XBAP applications no longer function when run from the Internet.[3] Attempting to run the XBAP will cause the browser to present a generic error message.[4] An option exists in Internet Explorer 9 that can be used to allow the applications to run,[5] but this must be done with care as it increases the potentialattack surface - and there have been security vulnerabilities in XBAP.[6]
For XBAP applications, code that exceeds the default permission set will have different behavior depending on the security zone. In some cases, the user will receive a warning when they attempt to install it. The user can choose to continue or cancel the installation. The following table describes the behavior of the application for each security zone and what you have to do for the application to receive full trust.
| Archiving only | |
|---|---|
| Compressing only | |
| Archiving and compressing | |
| Software packaging and distributing | |
| Document packaging and distributing | |
