Journal Journal: Enterprise Architect, anyone?
Just downloaded the EA demo application, which I am interested in using for Systems Engineering. Anyone want to weigh in on their experience with EA?
Just downloaded the EA demo application, which I am interested in using for Systems Engineering. Anyone want to weigh in on their experience with EA?
In this entry, I described something I thought was pretty anomalous. Since then, I've seen something very similar several times. The other day, I managed to get some 10x binoculars on it when it was right overhead. What I saw no longer looked like a point source, but an aircraft with orange lights running down the length of the underside of its fuselage. No running lights on the wingtips that I could discern. This must be some kind of military aircraft, perhaps a tanker, but its odd appearance is simply due to a bright underside light That seems to be roughly omnidirectional in its brightness.
I had hoped for something stranger, but at least there is one less wild goose to chase.
A little while ago, someone on Slashdot pointed me at the Sale of Goods Act in relation to purchased electronics. The act, for those unfamiliar with it, requires that goods be 'suitable for the purpose for which sold.' This is a fairly broad term, but it basically means that they must be able to do anything that the seller claims that they can do. Under this law, you have 6 years from the date of purchase to file a lawsuit if the item does not match the claims.
This was relevant to me because my MacBook Pro is now out of warranty and the battery is dying. Looking in the System Profiler, its full charge capacity was showing up as 1476mAh after 56 charges. When new, it was 5500mAh. These numbers don't mean anything by themselves, but Apple claims that their batteries retain 80% of their full charge capacity after 300 charge cycles. Claiming this means that a battery that does not retain 4400mAh after 300 charge cycles is not suitable for the purpose for which sold, and they are legally required to refund or replace it (irrespective of the time that has elapsed, although I can only sue them if they don't within 6 years of the time of sale).
I called their support line and was put through to an Indian woman, who explained that the warranty had expired. I quoted the relevant parts of law to her, and (after being kept on hold for a bit), was transferred to someone senior. He very quickly agreed to send out a replacement battery.
Interestingly, he did not ask that the original battery be sent out, nor that I provide a credit card number where I would be billed if the battery turned out not to be defective. I've had two batteries replaced in warranty, and this was standard procedure then, so apparently I get better service out of warranty. I don't have a great deal of use for a battery that only lasts about 35 minutes on a full charge, but I'll probably keep it as a spare.
As always, it pays to know the law. It's a shame that Apple, which claims to be a customer-focussed company, doesn't educate its support team about this though. Possibly the Indian call centre deals with people from everywhere English speaking, while the Irish one only deals with people in the UK and Ireland, so the people there are more familiar with British law, but if I had not quoted the relevant act then I would have been charged £99 for a battery, on top of the £1.50 it cost to call their support line for half an hour.
Some time around 2005, Slashdot ran an article about a new hosting company, MacMiniColo that was taking advantage of the new machines that Apple had just released to offer cheap hosting. I got in contact with them, and a little while later, I had a Mac Mini, sitting in a rack somewhere, running OpenBSD and acting as my dedicated server. A 1.42GHz G4 CPU, 512MB of RAM, and an 80GB disk was (and still is) more than adequate for my needs. The biggest load on it is eJabberd, and even that only used under 1% of the CPU.
I had really great service from these people. The hard drive failed a little under a year after I bought the Mini, and Apple refused to honour the warranty because they couldn't find the records of the sale (then, a few weeks later, they could, but by then it was out of the warranty period). MacMiniColo replaced the disk for me at their own expense.
After five years with them, however, I had a little look around and noticed that VPS hosting has gone down in price a lot. I've written a book on Xen, so I thought I might try a Xen-based VPS now that FreeBSD has Xen support.
GigaTux only claims to offer Linux, but I dropped them an email and they were happy to install FreeBSD for me. I still haven't tried the Xen-enabled kernel yet; they installed the stock x86-64 kernel in an HVM domain for me and performance has been fantastic.
I'm sharing a server with 64 other guests and in spite of that performance tends to be better than my ageing Mac Mini. I was getting 1000IOPS while untaring the ports tree, which is far more than the Mini's old 2.5" laptop drive could handle, and is amazing considering that it's going via the slow, QEMU-derived, emulated device, rather than the fast PV driver. I've been installing software from ports, so everything is compiled on the machine, and even that has been fast.
And my Mini? They found someone else who wants it, and offered me about a third of what I paid for it originally - not bad depreciation after five years of constant use. Shipping it back to the UK would have cost almost as much as buying one on eBay, so I sold it on. Hopefully someone else will get some good use out of it.
As an aside, I've been really impressed by how well OpenBSD works on Mac/PowerPC hardware. If you've got an old Mac Mini lying around, chuck OpenBSD on it and you've got a reasonable low-volume server. The newer ones, of course, are x86 hardware, so will run just about anything.
There are two reasons why I don't use GNU/Linux: One is GNU, the other is Linux. Of these, the larger reason is GNU, and specifically the glibc part. The most recent reinforcement of this is Ulrich Drepper's inability to read the C specification.
For those not familiar with the C specification, all identifiers that start with an underscore are reserved for the implementation (see section 17.4.3.1.2). You should never use them in your own code, because your compiler is completely free to do whatever it wants with them. By convention, single underscores are used for global non-standard libc extensions and double underscores are used for compiler builtins.
You can find a number of these in existing compiler. Microsoft exposes SEH with keywords like __try. GCC provides __asm for inline assembly, ICC uses __cpuid for accessing the CPUID instruction, and so on. Clang added __block as a type specifier for their variables that are copied to the heap for use by blocks (closures).
Unfortunately, it turns out that the glibc headers use __block as a parameter name. There are several things wrong with this. One is that they use double underscores at all. By convention, these are reserved for the compiler, while single underscores are reserved for the libc. The second is that they used underscores at all in a parameter. Parameter names are not in the global scope, so they can be anything to prevent name clashes.
The result of this is that, if you use glibc, you can't also use blocks. This is a shame, because we (Etoile) were shipping a working blocks implementation six months before Apple. Well, working on *BSD and Solaris (and probably Windows, QNX and Symbian with PIPS, but not tested there). This problem means that it doesn't work on GNU/Linux.
No problem for me. I only use platforms with libc implementations written by people who can read specs. It may be a problem for some of you, if you use a broken platform with a libc maintained by someone who'd rather salvage his ego than fix a problem, and if it is then I'm sorry for you. My suggestion is that you remember that there are other options.
I saw recently that FreeBSD 8 was in BETA state. I ran 7-CURRENT for a while, because it had features I wanted to test (improvements to the OSS implementation mainly), so I thought I'd give it a try.
This time, rather than doing my usual source install, I tried a binary upgrade using freebsd-update. What a disaster. While the source upgrade procedure uses mergemaster to update configuration files, letting you just keep the new version of files you haven't modified, freebsd-update makes you merge them all by hand where there is a conflict. This wouldn't be a problem, except that all of the config files have a version line at the top, which conflicts between the two versions.
Inevitably, when manually handling the merge for a few dozen files, I missed an important bit so my first boot failed with an error complaining about the diff lines still being in the file. I fixed that, and rebooted.
My next boot failed because one of the startup scripts had replaced an if statement with a case. Unfortunately, this hadn't shown up as a conflict, so it had just taken the start of the case statement and the end of the if, giving nonsense. Fortunately, I was able to find the correct version in CVS and copy it out.
Next boot, my network interfaces weren't working. Actually, this was a problem I'd found earlier. When you update FreeBSD, you update the kernel, reboot, then update the userland (the new kernel is guaranteed to support the old userland, but the converse is not true). The em driver for Intel GigE cards complained that they both had invalid MAC addresses. Not a huge problem; it's a VM so I could just change the kind of virtual network card it was providing to the machine, but checking the bugs database I discovered that it's giving the same error for people with ThinkPads that actually do have this kind of hardware built in. Great.
Finally, my system decided to fail to boot with the error:
mounting
/etc/fstab failed, startup aborted
Strange, I thought, I wonder which disk is failing to mount. A quick check in single-user mode showed that everything in fstab had mounted correctly. I eventually tracked this down to a bug in
I've run betas, release candidates, and even the development branch of FreeBSD before, but 8-BETA2 is the first time I've ever had a FreeBSD install that feels like a beta. The merging done by freebsd-update seems completely broken; it prompted me for things it could have trivially done automatically, but failed to prompt me when it broke random system files. My system is now working again, but it's irritating to have to spend this much effort on an update.
Does anyone remember Frontier, a space trading game from the '90s? No, not that one, but a much lesser-known top-down game that only ran on Windows NT. It was released back in '95 and I found it a couple of years later when I was running NT 4 on my PC.
The game was incredibly addictive, but it was unfinished. The version I had was 0.5, and Altavista (this was a few years before Google) was unable to find a newer version. The gameplay owed a lot to games like Nethack. You started off in one solar system and then got to the next through a jump gate (analogous to descending to the next dungeon level). Over time, you'd upgrade your ship, with better shields and weapons, and progress further. Being a 0.5 release, there were a few things missing. The lack of sound was a shame, but the real killer was that there was no save system. You could play for an hour, then get hit by a stray nuclear warhead and have to start from the beginning. A game with so much potential, but it never went anywhere...
There's one down side: It's still Windows-only, and I don't have a Windows machine anymore. Fortunately, it runs very well in WINE. I've playing it on the Mac in the free version of CrossOver Games that was released last year.
Oh, and if anyone's interested, you can still download Frontier 0.5. It does have one advantage over the newer game; the AI didn't have any sensible friendly-fire logic, so you could easily destroy (and loot) friendly space stations by getting one of the ships defending it to fire while docked. This was easy to do: just get the pirates to chase you there and when their stray shots hit the station all of the docked ships will launch firing. This works really well for the black market outpost, which is protected by very powerful ships and is full of fun technology to steal.
For a while now I have been maintaining a Google Calendar that keeps track of various FOSS release schedules. The currently monitored projects are:
Other projects that I don't follow as closely or don't have well-defined dates (End of November isn't specific enough, OpenOffice) may occasionally be added if I check (KOffice & OpenOffice have a few entries ATM). I update the calendar on the first Saturday of the month.
If there are other projects with a good schedule page that you would like to see tracked on this calendar, let me know.
It's been more than 30 years since I took a stats course. Any recommendations for a good, not overly dumbed-down intro stats book that uses R?
Fast, cheap, good: pick two.