Older blog entries for lloydwood (starting at number 90)

1 Aug 2010 (updated 1 Aug 2010 at 15:16 UTC) »

Playing with SaVi again

I've added a simulation of the NeLS constellation to my SaVi satellite visualization software . This was prompted by stumbling across papers that used NeLS as the basis for analysing the effects of overlap of satellite coverage areas on the use of intersatellite links in a mesh constellation -- papers based on the work in Chapter 7 of my PhD thesis and my 2001 AIAA diversity paper.

As I never got around to fleshing out that work with a journal paper, it was pleasing to eventually discover that someone else had done so, copying my simulation method and validating my results.

(My PhD thesis has been cited fifty times now, which is either a reflection of being useful to others, or of just being on the web.)

More fun with MIL3 Opnet

I previously described problems using MIL3's Opnet simulator under linux.

I've just discovered that the Opnet error log in ~/op_admin/err_log is 128 MEGABYTES in size. Silently created, stealthily lurking.

Remember, kids, it's all about application and network performance.

9 Jun 2010 (updated 11 Jun 2010 at 10:56 UTC) »

Fun with MIL3 Opnet

MIL3's Opnet 16.0 was installed on a local network today, so I thought I'd try it out.


> opnet &
[1] 28779
> 
********************************************************
NOTE: Use of 'opnet' as the program name is deprecated,
and will not be supported in future releases. Please use
the actual program name to run the software.
********************************************************

Right, I should have invoked it by typing modeler, with the US spelling. Rather than 'modeller,' as it's spelt in the rest of the world. That was followed by a bunch of warnings indicating that maintenance had expired, i.e. under the educational license (which expires next month and will need to be renewed) I'm on my own.

I tried building a test scenario, including a few things I thought I'd need. IP, Cisco stuff, TDMA... nothing fancy. I've spent the last six hours staring at a 'Please Wait' dialogue (sorry, dialog) alternating between 'Validating Demand Self-Description Database' and 'Validating Node Self-Description Database' while beeping. Eventually, I figured out how to disable the beep in the parent terminal.

Somehow, I don't think I'll be using Opnet Modeler for anything much, much less using Opnet Modeler for anything useful. So it's back to open-source ns; better the devil you know.

Update: It finally died after seven or so hours:


<<< Program Fault >>>


* Time: 17:58:16 Wed Jun 9 2010 * Product: modeler (32-bit) * Function: mmi_msg_tip_show_handler * Error: program abort -- segmentation violation

That's nice.

Update 2: Turns out the modeler binaries don't get along with Ubuntu 9, but are better behaved on Fedora Core. Shame we're switching to Ubuntu, really. The clue was that MIL3 supports Red Hat. Linux binary compatibility? Ha.

29 May 2010 (updated 29 May 2010 at 22:47 UTC) »

Wired goes a bit CD-ROM

Wired Magazine have launched their latest issue as an iPad app costing US$4.99. It's large enough to require a CD-ROM to save a copy on.

The app will fill up 527 mb of your iPad storage space and takes approximately 10 minutes to download. [..] Here are a few issues I found within the app. First was the price. I’m sure I won’t be the only one complaining about the ridiculously high price per issue when you can easily buy a year’s worth of the printed copy for only $10. Also the file size is cause for concern. Not only is the app 527 mb too big, but it takes a long time to download and if you only paid for the 250 mb data plan for your 3G iPad, you’re just sheer out of luck.
-- WIRED Magazine for iPad review, Mary Ann Neder, IPADMODO, 28 May 2010.

You could fit a movie in that app filesize. Or the complete works of the Beatles.

all the fonts on the Wired app were rendered on a desktop platform, and provisioned to the app in the form of flat PNG files. The Wired app does not use the iPad’s rendering software at all.
-- Comment by Jonathan Hoefler to: WIRED on iPad: Just like a Paper Tiger… by Oliver Reichenstein.

Well, that's one reason why the app is so large. The other would be the included advertisements that you buy along with the app.

And how does screen reading or translation software work with flat PNG files?

it all seems a bit CD-ROM.
-- cd-roms and ipads, Danny O'Brien, former Wired journalist, Oblomovka, 1 April 2010.

(It's a pity for his comparison that the Wired app is only available through iTunes, and not included in a CD-ROM on the cover of the printed magazine as well.) How long will Wired's venture into e-publishing for a single platform last? Danny's musing on production costs and comparisons with CD-ROMs, and the demise of Wired UK the first time around suggests not very long at all.

M y opinion of Wired hasn't changed. It's still easier and cheaper to read their articles online with a web browser. Still, iPad early adopters are by definition Wired's target audience, explaining the claims of 24,000 app copies sold with the first edition of the app. There's a sucker docked every minute. Better hope they don't want continued access to back issues; two years' worth of issues this size will fill up the 16GB iPad.

Still, this publishing venture won't last that long in this form.

Apple's developer restrictions

Much fuss of late over Apple's changes to its iPad/iPhone developer agreement banning use of interpreters and translators. It's claimed to be all about preserving battery life and the user experience, or Apple's control of their manifest destiny, depending on who you read.

But what if it's also a way of encouraging use of Xcode and Macs, and (inadvertently?) promotes Xcode/Objective-C development on the Mac? Mandating that iPhone developers use Xcode and Objective-C leads to encouraging Objective-C for Mac development as a side-effect. It promotes not just iPhone/iPad expertise and iPhone/iPad-specific applications, but leads developers towards creating more feature-filled Mac-specific applications - rather than poor ports from Windows or from Unix/X (my SaVi satellite visualisation software is an example of the latter. It's suckily minimal-effort crossplatform.)

Shortterm, this restriction benefits the iPhone/iPad. Longterm, this may lead to compelling Macintosh-only applications; it's been a long time since there have been many of those.

But it's still all about Apple's control of its manifest destiny; no change there.

13 Apr 2010 (updated 13 Apr 2010 at 16:48 UTC) »
I blinked.

Although NTT DoCoMo removed some HTML tags, it also added some new ones. The <blink> tag makes text turn on and off.

-- Andrew S. Tanenbaum, Computer Networks, 4th edition, section 7.3, p. 669, Prentice Hall.

Louis J. Montulli II disagrees about the origins of <blink>, of course. And Tanenbaum follows that with an introduction to WAP.

It's entirely fair to say that the fourth edition of Computer Networks could be better, though it's perhaps not as poor as the third edition. I think the second edition provides a graceful introduction to the importance of networking layering, even if it is somewhat OSI-centric, and that it is much better for learning about fundamental principles of networking. The second edition is timeless. The fourth, not so much. But then it's trying to cover much more ground.

Gnome again, Gnome again, jiggety jig

I've previously discussed my success in filing Gnome bugs. I filed a report on a trivial coding error with GIMP plugins - pretty basic beginner shell- script quoting-variable problems - to be told that I'd need to fix it myself.

So I looked at developing for GIMP. The GIMP developer documentation currently says GIMP development is done using CVS. Apparently that's no longer true, and it's now done using git, after skidding through subversion somewhere along the way. And their documentation hasn't been updated. I couldn't find out why the code management toolset was changed, but I imagine fashion has an awful lot to do with it.

So. "We won't fix your bug, and we won't update our documentation to tell you how to become a GIMP developer so you can fix it yourself." Awesome.

Well, so much for me contributing to GNOME. All hail the magic sharing pixie dust power of open source!

6 Dec 2009 (updated 6 Dec 2009 at 23:56 UTC) »

I released SaVi 1.4.3 today; just a six-monthly minor update staying current with distributions, and checked to work on Mac OS X Snow Leopard, Fedora 12, and Ubuntu 9.10.

Sourceforge's admin interface has changed a lot since my last update, and not necessarily for the better. Figuring out the file release widget took some doing.

SaVi

As I'm now finding myself with free time, I played a little with my SaVi satellite visualization software to bring it uptodate with compilers and platforms, and pushed out a SaVi development update.

In doing this, it was interesting to discover that:

  • the Mac OS X menu breakage in 10.5 Leopard's Tk 8.4.7 is fixed in 10.6 Snow Leopard and Tk 8.5.7. SaVi finally has the look and feel of a bona fide Mac app, albeit one that requires XCode, being compiled, and being launched from the command line. Tk's infinite looping when listboxes are too large is fixed too. Should I somehow specialcase for 10.5?
  • Installing Ubuntu 9.10 under VirtualBox is really slick and easy (though its packaging of Tcl and Tk seems a little odd.) If you're on Windows, I think it's now preferable to Cygwin, which is less good than it used to be.
  • Installing FreeBSD 7.2 under VirtualBox is not slick or easy. Attempting to set it up on a Mac, of all things, just feels wrong, and that's before you get to selecting partition sizes in the 80s DOS character window of yore. I gave up.
  • Ubuntu's gcc 4.4 really is pedantic. Every conversion from unsigned to signed or from non-const to const gets mentioned. And just when I thought I had fairly clean code…

Also interesting to note a recent unheralded SaVi rendering appearance in a post by Mark 'Robert X. Cringely' Stephens. Requests for an attribution were ignored and deleted. Charming. Interestingly, it's the same SaVi Teledesic rendering that was reused without proper attribution in a rather poor 2000 IEEE Communications Surveys paper; they took it down, and rethought their editorial policies and such. Not Cringely. Cringely's Wikipedia page told me all I needed to know.

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