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A GUI for ps(1) Built with Mozilla

Issue 123

From Issue #123
July 2004

Jul 01, 2004  By Nigel McFarlane
 in
Give your command-line tasks a GUI with the Mozilla platform.

instead of: 

mozilla -chrome file:///home/nrm/psviewer/tree.xul

The psviewer tool has first-class status within the Mozilla installation. If necessary, it could be integrated with other applications, such as the Firefox/Firebird browser or Thunderbird e-mail client. It also could be added as a menu option to the Tools menu, for example.

There's a lot of technology in this article. The biggest mistake you can make is to try to use all the features described here in your first Mozilla experiment. Because validation of XML is less than verbose in Mozilla, you easily can become tied in a knot. It's best to start with a simple project and work up to the challenging combinations played with here. Although the output of ps(1) also can be made into a dynamic HTML page, XUL is a more robust and professional GUI in the end, fully integrated with the desktop.

Mozilla is a powerful GUI environment waiting to be explored. It is likely to occupy the same niche under Linux that Visual Basic occupies under Windows. Even better, Mozilla is a portable and cross-platform technology. Your projects can be designed to work on BSD, HP-UX, SunOS, AIX and Mac OS X, as well as Linux.

Nigel McFarlane is a freelance science and technology writer with an extensive programming background. His latest book is Rapid Application Development with Mozilla, ISBN 0131423436. Reach him at nrm@kingtide.com.au.

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Anonymous's picture
Submitted by Anonymous on Mon, 07/26/2004 - 02:00.

I'm the author. I've placed a download containing some notes and minor fixes on the Web to ease the process of experimentation a bit. Get them here.

- Nigel.

Re: A GUI for ps(1) Built with Mozilla

stoneknife's picture
Submitted by stoneknife (not verified) on Thu, 06/24/2004 - 02:00.

For the most part I liked this article, particularly as I could use some of the theory behind it for a project of my own. I would like to point out, though, that neither the listings nor the text indicate directly what file names the listings might assume. Some of that can be figured out but it would have been nicer to have that available within the text.

When typed in, and also later downloaded from the archive sight, the code from the listings failed to output what is reported in the figures.. at least for the final. I'm no JavaScript programmer by any means but it appears that the initial definition of 'psdata' (listing 2) should not be 'null' but a new something, probably Array, as that has an attribute of 'push' (as used later in the code).

It would also have been nice for the second JavaScript excerpt (listing 7) to have some kind of indication that it should be inserted into the initial JavaScript (listing 2).

Ok... so I learned something in having to dig into the workings to get it working. It was a good start anyway aside from my frustration..

Re: A GUI for ps(1) Built with Mozilla

Anonymous's picture
Submitted by Anonymous on Wed, 07/14/2004 - 02:00.

Notice also that execute_ps has a full path to the executable specified. This has to be changed as well.

After making the recommended changes in the first reply, and the above mentioned change. It crashes in a miserable fashion. No clue what the error means. It appears that certain assumptions were made in navigating the data tree, and these aren't valid across versions of Mozilla.

I really like the potential of XUL and it's got enough excitement here at work, that they're talking about rolling out Mozilla to 1000 PC's if it works as promised. It's a pity that the example in this article can't be made to work simply.

Re: A GUI for ps(1) Built with Mozilla

BArchis's picture
Submitted by BArchis (not verified) on Sat, 07/17/2004 - 02:00.

I've been banging my head on this for a few days, and have been able to get it to work with Mozilla built from source, as well as a binary downloaded from mozilla.org. Some thoughts:

1. The package >>must<< be registered as chrome and the .xul file invoked as 'chrome://...' or it won't work: you'll get an empty form because the JavaScript security won't be satisfied. It's probably easier to set up the registration and the .../chrome/psviewer/content directory first and then start building the code inside it.

2. When you build Mozilla from source, you get xpcshell, which allows you to invoke JavaScript files from the command line. It can help in getting the portion of code in Listing 2 working, but will not help with the combined (Listing 2 and Listing 7) JavaScript, because the operating context (i.e. we invoked the JavaScript from an .xul document) is missing.

3. Combining Listings 2 and 7 is a little more involved than simply concatenating them. You want to have all the declarations, followed by all the mainline code, followed by all the functions. (Maybe they don't absolutely have to be in order: I'm not a JavaScript jock. But it's much easier to follow what's happening.)

4. If you'd like, you can put the JavaScript inside the .xul file.

So now I've got it working, almost: if I invoke it as:

chrome://psviewer/content/psviewer.xul

(whether from the command line or in the address box)
it works (it even updates if I hit the Refresh button!), but if I invoke it as:

file://path/to/mozilla/chrome/psviewer/content/psviewer.xul

(or point File Open to the .xul file)
I get an empty form.

Why do I say 'almost'? Since I have this cool picture of the running processes on my screen, I'd really like to print it. But when I try to print it, the text disappears from the table, and when I try to do a Print Preview, Mozilla tosses its cookies with a segmentation fault.

Perhaps that's an exercise for another month....

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