Topic: Hi,Experts,Can you tell me what is "mission critical"? what is "real time system"?TIA @枫下论坛 The Rolia Forum

工作学习 / IT杂谈 / Hi,Experts,Can you tell me what is "mission critical"? what is "real time system"?TIA -deepyellow(DeepYellow); 2001-1-9 (#20964@0)

Just some buzz words -jabber(jabber); 2001-1-9 {205} (#20967@0)
Roughly speaking, mission-critical means very very important, real-time system means "not a demo". You can see such words in flyers, ads, web sites... Hope you can use these words in your job interview.
Arguing about Real Time systems -jfhuang(Zigzag); 2001-1-9 {818} (#21009@0)
I would like to argue about this with Mr. Jabber.

Real time system does't only mean it is not a demonstration propram. Actually it is a special field of computer applications.

A Real-time system must not only produce logically correct results, but it must also produce them with certain timing constraints. That is, the application has to produce required signals at required time points. So this field is strongly related to real time signal processing . In fact real time systems are mostly applied in industrial controls, automated factories, telecommunications, computer speech synthesis etc, which are all timing critical applications.

By large, real time system includes the steps of controlling the real life objects. So programmers usually have to have the knowledge of automatic control theory.

agree! -yfy_ca(yfy); 2001-1-9 (#21015@0)
ZigZag, you are right! My posting was too casual. -jabber(jabber); 2001-1-10 (#21098@0)
Just one addendum: Java is not a real-time system. -jabber(jabber); 2001-1-15 (#21725@0)
Two of the most popular RealTime OS now are: pSos/pSos+, and VxWork. They are widely uesd in Telecommunication System -bills(Bill); 2001-1-15 (#21754@0)

By the way, Windows NT 4.0 does not meet all the requirements of real time system. -jabber(jabber); 2001-1-15 (#21761@0)

Even UNIX is NOT real Real-time OS. When we talk about Realtime OS, is always mean embaded-realTime OS, such as pSoS, vxWork. -bills(Bill); 2001-1-15 (#21804@0)

One more addendum, real time system is specified by POSIX 1003.1b. -jabber(jabber); 2001-1-16 (#21876@0)
I just wonder, how big the pSoS, vxWork. I think the embedded software couldn't too large. And is vxWork a Unix like system? -rock_jack(Rock Jack); 2001-1-16 (#21885@0)

Of course vxWORK and pSOS is very small as the most popupar embaded OS in the world. VxWork & pSOS are totally diffirect with Unix. Now almost all telecommunication Equipment use pSOS/pSOS+ or vxWORK. -bills(Bill); 2001-1-16 (#21887@0)

Dear Jabber,real-time systems can run on a lot of OS, sometimes even don't need a OS. -guest:Dolphin; 2001-1-16 {1253} (#21889@0)
本文发表在 rolia.net 枫下论坛When we use sigle-chip computer or single-board computer to serve in real time system, we simply compile programs from assembler language into machine-code. At this moment we have no OS running on the computer. Every instruction must manuplate registers directly.
On the other hand, a lot of OS can be used for sophisticated real-time systems. For instance, we have real time system running on Windows 3.12, we also have system running on Sun Saloris. The OS just serve as a platform. It's the real-time control software who master the whole "real-time" system.
I understand that u r dubious of wether WinNT is strong enough to prop real-time applications. However, we have other stategies to handle the cracking down of a real-time system. For example, simply shut down whole system or swich to manual control. Of course, the perfect system will has a backup system.
I can not agree to your opinion that Java is not a real-time system. Actually, Java was born for real-time system--Web TV. Also, Java will be used for a lot of real-time applications, like Kiosk, embedded intelligent control system.Maybe someday you will also find it running on your home appliances and try to control your life--a dream,he he. This is what the microJava for.更多精彩文章及讨论，请光临枫下论坛 rolia.net

Hi, bill,I have a question that in a real-time application, is progrmmer's duty to assign priority and schedule tasks at application level, or it could be taken care by RTOS.? thanks. -rock_jack(Rock Jack); 2001-1-16 (#21966@0)

For Your Reference -guest:Dolphin; 2001-1-16 {715} (#21873@0)
Mission Critical means tasks must be completed in a very very secure way. For example, banking bussinesses. All those missions not only need robust programs but also need fault-tolerant hardware systems, saying, disk-array, redundant system device etc. Systems claim to serve "7 days, 24 hours" are all "Mission Critical".
As to Real-time System, you can see the meaning from its name literally--it needs to react to all requests instantly according to some preset method. Often, it is used to call computer control systems in machines, in streamlines and etc. Nonetheless, nowadays it's also evoled to name system which is "Timing Critical"--just like Zigzag said. An example is Quoting-Broker system.