Question: I have a rather unusual idea. I want to run a single instance of a Java EE application client inside app server, in a similar way that JMS provider is run/embedded "within" the app server, so that it is started and stopped with the app server. Why? To ease deployment and maintenance of a complex distributed Java EE system which has application client as part of its architecture.

So:

1. There is only one application client on each server where there is app server (Glassfish).
2. I would like to have the application client run in the same start-stop cycle as the application server, and not as a totally separate entity run under a (apache or similar) system service wrapper.

Is this possible?

Answer: 
I use Awesomium, I think it is better than GeckoFX/WebKit
<http://awesomium.com>
**Update 2016:**

Unfortunately most of the above solutions are out of date and no longer maintained. 

There are 3 additional options I can suggest that are still actively developed:

[1. BrowseEmAll.Cef](http://www.browseemall.com/CoreAPI/Cef)

A .Net component that can be used to integrate the **Chrome engine** into your .Net Application. Based on [CefGlue](http://xilium.bitbucket.org/cefglue/) but a little faster on updates to the latest Chrome version. Also there is a **commercial support** option available which might come in handy for some. Of course the component itself is **open source**. 

[2. BrowseEmAll.Gecko](http://www.browseemall.com/CoreAPI/Gecko)

Another .Net component which can be used to integrate the **Firefox engine** into your .Net application. This is based on [Geckofx](https://bitbucket.org/geckofx/) but unlike the current version of Geckofx this will work with a normal release build of Firefox. To use Geckofx you will need to build Firefox yourself. Again **commercial support** is available but the component itself is fully **open source**. 

[3. BrowseEmAll Core API](http://www.browseemall.com/CoreAPI)

Need all the different browsers in your .Net Application? Which the BrowseEmAll Core API you can **integrate Chrome, Firefox, Webkit and Internet Explorer** into your application. This is a **commercial product** though so be warned.

*(Full disclosure: I work for this company so take everything I say with a grain of salt)*