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- jtp51, on 10/10/2007, -20/+1Wonder what happens when a Null Pointer Exception is thrown?
- DickBreath, on 10/10/2007, -1/+23The same thing that happens in C++? What happens if you have a null pointer in C, ooops, no exception is thrown.
Let me rephrase your question: what happens if the application software has a bug?- ashishwave, on 10/10/2007, -0/+1right dickbreath.
rather than blaming ones own shoddy coding of application if someone blames java or OS , then no tool/no toy can save his app in any platform.
- ashishwave, on 10/10/2007, -0/+1right dickbreath.
- DickBreath, on 10/10/2007, -1/+23The same thing that happens in C++? What happens if you have a null pointer in C, ooops, no exception is thrown.
- DickBreath, on 10/10/2007, -5/+12It is interesting that a high level language WITH GARBAGE COLLECTION can be REAL TIME, with a suitable runtime system like PERC.
(Note: real time, means guaranteed response times. This function call is guaranteed to return in XX milliseconds, even if it allocates memory, etc.)- sp1nm0nkey, on 10/10/2007, -4/+4Yeah, garbage collection can be deferred to a low priority background thread, somewhat like how used memory is scrubbed before it's given to another process. Real time means not only that it's gonna return within a certain time, but that the whole system is set up to enter and exit procedures on a deadline. Running an alarm clock is a good example of a real time task, you can't queue up time passing, the digits have to change when the time changes or within an acceptable threshold. The thing is, that acceptable threshold is getting stupidly high nowadays and real time is somewhat of a buzzword... it doesn't really take a real time system to control traffic lights, and if you really wanted a real time system you wouldn't use java, which is bloody slow and puts another huge layer between the interrupt and the completion of the task. Basically, real time == buzzword, java == buzzword, whole thing is a silly.
- vocaro, on 10/10/2007, -0/+8Most likely, the system isn't using garbage collection at all. It's probably using scoped memory, which is harder to use than garbage collection but more predictable.
- brownzilla, on 10/10/2007, -2/+1Its not just the time that garbage collection takes, but it adds a huge amount of unpredictability ecspecially with determing memory bounds. Real-time Java is like windows CE being real-time: both use very liberal and inaccurate definitions for real-time.
- ciotog, on 10/10/2007, -0/+2Do you have any references to cite with respect to the RT Java runtime mentioned in the article?
- vocaro, on 10/10/2007, -0/+1No, brownzilla, memory bounds checking can be performed in constant time. Thus, it only affects performance, not predictability. And contrary to your assumption, real-time Java is indeed real-time, as long as it has support from the underlying operating system (e.g., a fair scheduler) and and an implementation of the Real-Time Specification for Java.
- picsectionpleez, on 10/10/2007, -2/+3now if we could just get it to dispense beer and schnitzels
- gavintlgold, on 10/10/2007, -0/+1Trivia: What is a wiener schnitzel and what does it mean in German?
- keyboardduder, on 10/10/2007, -4/+3or you could just automate all of them by just planting a few basic ICs in the lights.
- UKsHaDoW, on 10/10/2007, -2/+11Your living in the past, Traffic Lights can be updated and controlled remotely to optimise traffic at different times. A 555 timer and decade counter won't do that.
- Salgat, on 10/10/2007, -0/+2But a PIC microcontroller will.
- dkoon, on 10/10/2007, -2/+3Seriously, what can Linux do to the traffic lights to make it "Safer"? Compiz/Fusion traffic lights?
- specialK16, on 10/10/2007, -0/+7Well if you are DUI, you don't need any Compiz Fusion at all.
- RonDutt, on 10/10/2007, -0/+7Compiz/Fusion traffic lights = really long traffic lines since everyone is looking at the purty colors :P
- UKsHaDoW, on 10/10/2007, -2/+11Your living in the past, Traffic Lights can be updated and controlled remotely to optimise traffic at different times. A 555 timer and decade counter won't do that.
- mercurysquad, on 10/10/2007, -4/+3grossly inaccurate title.
- rauz, on 10/10/2007, -1/+3Mildly misleading title and description since they moved from one Linux distro to another. Still kind of interesting.
- spyd3rweb, on 10/10/2007, -5/+4use C next time.
- u16085, on 10/10/2007, -0/+3Lock describes Signalbau Huber as one of Germany's two largest traffic managment system vendors. He said the company's systems are used in Frankfurt, Stuttgart, Prague, Budepest, Vienna, Poland, Warsaw, and Benelux, among other European locations.
Isnt Warsaw In Poland? wtf ...?- Sigurdhsson, on 10/10/2007, -2/+2Do you have a problem with that?
For once they DIDN'T forget Poland...- SimonGray, on 10/10/2007, -1/+2They already mentioned Poland right before Warsaw...
- solis365, on 10/10/2007, -3/+4um... and vienna, benelux, prague, and budapest arent in germany either...
its germany's largest traffic management system vendors. im sure they supply internationally.- Tippis, on 10/10/2007, -0/+5I think his point was that they mention Poland and Warsaw as if they were two separate things -- if they specify one, they didn't really need to specify the other.
- Sigurdhsson, on 10/10/2007, -2/+2Do you have a problem with that?
- tamarindwolf, on 10/10/2007, -7/+0Why don't you people check out my lone submission, and digg it up?
- Nefi, on 10/10/2007, -0/+4i'll bury it since you asked like that.
- tamarindwolf, on 10/10/2007, -2/+0And how many have you submitted?
- trogdoor, on 10/10/2007, -0/+3And how does that make a difference?
- tamarindwolf, on 10/10/2007, -2/+0And how many have you submitted?
- mikesbaker, on 10/10/2007, -1/+2http://img154.imageshack.us/my.php?image=buryth0.jpg
- tamarindwolf, on 10/10/2007, -5/+0Your just jealous of me.
- Nefi, on 10/10/2007, -0/+4i'll bury it since you asked like that.
- Papajohn56, on 10/10/2007, -8/+0Too bad they didn't use a real OS, like BSD
- livevil, on 10/10/2007, -4/+7apt-get green light;apt-get remove stopsign
- mercurysquad, on 10/10/2007, -0/+3you forgot sudo
- jisatsusha, on 10/10/2007, -0/+1They might be using Debian.
- mercurysquad, on 10/10/2007, -0/+3you forgot sudo
- Amablue, on 10/10/2007, -6/+1Is that why the red lights take so long?
- Papajohn56, on 10/10/2007, -3/+2should've used BSD and assembler
- strangewill, on 10/10/2007, -0/+4Why use assembler if the whole big deal about Unix is C?
- Papajohn56, on 10/10/2007, -3/+2should've used BSD and assembler
- takua108, on 10/10/2007, -1/+5sudo green
- rinks, on 10/10/2007, -4/+21Of course, 99 percent of the cars on the street won't be recognized by Linux.
Which means they need new... wait for it... DRIVERS.
w/e- takua108, on 10/10/2007, -2/+0Meh, pun should've been made in reverse, or should've been some sort of witty nVidia/ATI joke.
- thewindfish, on 10/10/2007, -2/+1I hate you I love you
- uepuarq, on 10/10/2007, -1/+1Let's hope Germany has learnt from the recent hacking of the Washington traffic light network.
- telengard, on 10/10/2007, -6/+1Real time java? That's an oxymoron right? Must not be a hard real time application...
- beders, on 10/10/2007, -0/+2Dude, you have no idea.
Java has initially been invented for embedded devices and real-time applications (Project green).
Here's more info on real-time java:
http://java.sun.com/javase/technologies/realtime/index.jsp
- beders, on 10/10/2007, -0/+2Dude, you have no idea.
- rtimmons, on 10/10/2007, -7/+5Of course the entire city's traffic grid will be asked to stop every few minutes to wait for garbage collection...
- ijib, on 10/10/2007, -5/+5Why does anyone need a general-purpose OS with a virtual machine running on top of it, just to run a single dedicated application which turns a few lights on and off? This is where bloatware comes from. A simple traffic light should be able to be controlled by a microcontroller running a program less than 100 instructions long, or even by discrete components.
- freeplatypus, on 10/10/2007, -0/+4Simple lights control: on/off
Not so simple:
1. Control via modem/GRPS/UMTS/CAN/LAN/etc
2. Autonomous operation in case of lack of communication.
3. Now make it manageable and maintainable.
Not that easy after all, or is it? - Tippis, on 10/10/2007, -0/+6A simple traffic light, yes.
A complete, remote-controlled, municpality-wide dynamic traffic routing system? No. - Dochtuir, on 10/10/2007, -0/+3you're right. for SIMPLE traffic systems. Not the case here.
- freeplatypus, on 10/10/2007, -0/+4Simple lights control: on/off
- djGentoo, on 10/10/2007, -1/+1Debian 3.2?
What happens when someone launches a DDoS attack?- Tippis, on 10/10/2007, -1/+1Blinking yellow lights, aka much better traffic flow ;)
- mwang1999, on 10/10/2007, -4/+1Hope the system doesn't CRASH... otherwise, it may not be the only thing that does....
- thewindfish, on 10/10/2007, -0/+2I think your pun crashed.
- JasonCox, on 10/10/2007, -7/+2Linux, ok, thats fine. But JAVA?! Ugh.
- databoy, on 10/10/2007, -0/+2I used to service traffic lights in Perth, Western Australia.
The traffic controllers are manufactured by Philips Australia. The site controllers are a specialised, programmable and complex microcomputer capable of intelligent management of traffic flow.
The unit mentioned in the article is needed to analyse the traffic flow in the chain. The master controller has to analyse all the controllers in the link and synchronise the traffic flow for the major arterial movement. Not an easy task.
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