Re: Mars Rover Controlled By Java
From: Michael N. Christoff (mchristoff_at_sympatico.caREMOVETHIS)
Date: 01/24/04
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Date: Sat, 24 Jan 2004 05:27:20 -0500
"Harry Conover" <hhc314@yahoo.com> wrote in message
news:7ce4e226.0401231929.229d375f@posting.google.com...
> "Michael N. Christoff" <mchristoff@sympatico.caREMOVETHIS> wrote in
message news:<6bFPb.16559$cQ6.521869@news20.bellglobal.com>...
> > > > Java is certainly not a member of this tight-knit
> > > > club of system implementation languages, and I simply cannot picture
> > > > anyone even attempting to implement a real-time OS using it.
> > > >
> >
> > As I mentioned, you would not implement the OS in Java, but would
implement
> > a VM for the OS that allows one to run Java code with deterministic time
> > contraints on operations.
>
> No, what you actually posted was (unless attrition of this to you was
> in error):
>
> "> > Java, the software developed by Sun Microsystems in the mid-1990s
> as a
> > > universal operating system for Internet applications, gave NASA a
low-cost
> > > and easy-to-use option for running Spirit, the robotic rover that
rolled
> > > onto the planet's surface on Thursday in search of signs of water and
life."
>
> Running Java code with deterministic time constraint on operations
> could be conceptually employed to construct a real-time OS, but in
> reality could not be done simply due to the fact that the Java
> implementation is so layered and ridiculously bloated, that it would
> be practically incapable of meeting the microsecond and millisecond
> timing constraints typically imposed on the deep end of a real-time
> operating systems.
>
> Certainly Java is capable of non real-time task such as the timely
> update of a wall clock time display, or the issuance of coontrol
> sequences based on clock time, but it depends of the capabilities of
> some RTOS to provide the time-of-day services on which it feed to
> provide these capabilities.
>
> Due to it's very high-order application focus (that it, consists of
> application level functions, not machine oriented instructions), I
> really cannot imagine of a Java implementation that would lend itself
> to RTOS applications, whether a VM implementation or not.
>
> Then too, I don't believe that this is what you are trying to say, and
> I believe the confusion is cause by someone erroneously attributed a
> quote from the Sun PR blurb to you.
>
> I suspect that tranlated to my language, what you're telling us is
> that one could employ a Java implementation running on top of the
> environment created by a real-time operating system, something that is
> routinely done.
>
> I have no problem with Java, its capabilities, or its applications,
> however I do strenuously object to the statement that: "Java, the
> software developed by Sun Microsystems in the mid-1990s as universal
> operating system for Internet applications, gave NASA a low-cost and
> easy-to-use option for running Spirit, the robotic rover that rolled
> onto the planet's surface on Thursday in search of signs of water and
> life."
>
> The simple facts of life are that Java was not developed as a
> "universal operating system for Internet applications" nor is a
> real-time operating system "option for running Spirit".
>
> Spirit's applications level software could well be Java, or Fortran,
> Basic, Jovial, Lisp, Forth (Ghod Forbid), or just about any HOL. My
> point is that you can damn't well bet that the RTOS that directly
> controls (both the good and now the bad on Spirit) is very likely
> programmed in a language providing direct machine instruction level
> control of its processor, likely C, C++, or assemly langage just as is
> the embedded bios in your computer, RAID server, or network
> controller.
>
> Fact is, the controller aboard Spirit is functioning as simply a
> glorified PLC, and likely has very similar embedded firmware to that
> of earthborne PLCs. Why wouldn't JPL copy this model, 90% of man's
> controller experience is using PLCs.
>
> Rant complete! ... -.-
>
> Harry C.
- Previous message: Anthony P.: "Re: So I guess MIT is not good enough anymore?"
- In reply to: Harry Conover: "Re: Mars Rover Controlled By Java"
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