Topic: xvfb

[Mark]

I don't mean to start a long thread about the pro's and con's of X-Windows on a server. I do have a question about x-windows virtual frame buffer.

I am looking at a product that requires X-Windows to run but does not require that it's output be visible. The developer suggests installing Xfree86 in order to use the xvfb device. This is supposed to strike a happy medium, that is, no output on the server and the application has a device to keep it happy. The obvious question is why someone would write a server product this way, but that is not my question for this list. I plan to put that question to the developer.

What is on my mind is whether installing Xfree86 on SME 5.6 will cause problems with stability, performance and so on. Also, can anyone relate their experience using the xvfb?

As always, thanks for taking a moment to reply.

 - Mark

[Scott Merrilees]

As to why, the product probably uses java, and some of the imaging routines require X11 library calls, and to access these calls requires a connection to an X11 server, thus xvfb.

I think this is fixed in later releases as in 1.4 or 1.4.1 there is a runtime parameter that can be given to java so it knows it is headless.    I haven't had the need to test this out as yet, but that is my conclusion when I did some searching the find out why Oracle 9i Application Server needed an X11 display.

My experience with xvfb is with Solaris & Mandrake, so I can't say anything definiitive about SME, however I don't see why it should be bad for your box.  Things I would pay attention to are security and resource utilisation.

From the security side, I would try not to install a real X server, just the virtual one, and watch out for any setuid files that may be installed, that you don't really want.  I would also run xvfb with '-nolisten tcp' if possible.

From the resouce side, apart from the chunk of space X11 is going the take out of your disk, I'd run it with something like '-screen 0 1x1x8', as this will reduce the memory footprint as much as possible.  You may need to adjust the screen setting to your application, tho.

Sm

[Mark]

Thanks, Scott, for the reply. I appreciate your suggestions. FWIW, the app does require a 768X1024 screen size, I will check on the Java runtime parameter, that sounds interesting.

 - Mark