As far as I know this isn't possible. If you wanted a message box that could be invoked from the server or the browser you'd be looking at creating your own little DSP to do the job unfortunately.

Thanks James, in that case how can i create a DSP that works like the "webmessage" (A pop-up modal dialog box)?

There are 101 ways to make a modal box,  the best way will depend on the specifics of your project. Just for the sake of discussion let's look at this tutorial http://www.webdesignerdepot.com/2012/10/creating-a-modal-window-with-html5-and-css3/ You could simply add this to a DSP and you'll have a working modal window that you could show and hide only on this DSP. Nice and easy! I mentioned that you could create a generic DSP to handle this for you, which can be a nice way to encapsulate the functionality so that you can use it in more than one place. I might start by putting the contents of the "openModal" div on this DSP, assigning the DSP to a DSP container would make the modal appear and removing it from a DSP container would cause it to disappear. You could even call an operation on the DSP whilst assigning it to the container in order to set the message text etc. I've been a bit vague, let me know if that makes sense and we can take it from there. Regards, James