Re: Applet can't detect 64-bit JRE

Discussion in 'Java' started by Roedy Green, Aug 18, 2011.

  1. Roedy Green

    Roedy Green Guest

    On Thu, 18 Aug 2011 13:58:11 +1000, "Qu0ll" <>
    wrote, quoted or indirectly quoted someone who said :

    >I have been using a locally-deployed applet for some time with 32-bit Java 6
    >on the client and it has been working fine. Since upgrading the client to
    >64-bit Java 7 I find that the applet cannot detect that Java is installed
    >and insists on downloading and installing a 32-bit JRE. I have since
    >discovered that the same thing happens even I downgrade to 64-bit Java 6.


    If you have a 64-bit browser it looks for a 64-bit JRE. IF you have a
    3.2-bit browser, it looks for a 32-bit JRE. that is why I have a
    32-bit JRE and 64-bit JDK installed.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com
    Most of computer code is for telling the computer
    what do if some very particular thing goes wrong.
    Roedy Green, Aug 18, 2011
    #1
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  2. On 8/17/2011 10:21 PM, Qu0ll wrote:
    > I stand corrected - it appears that only Java Web Start *applications*
    > work with this combination, all other true applets result in an attempt
    > to download and install a 32-bit JRE or complain of missing plug-ins.
    >
    > Why should there be any difference???


    I think it is because the Applet runs in the browser plugin and JWS runs
    the installed JVM.

    --

    Knute Johnson
    Knute Johnson, Aug 18, 2011
    #2
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  3. Roedy Green

    Lew Guest

    Qu0ll wrote:
    >>> If you have a 64-bit browser it looks for a 64-bit JRE. IF you have a
    >>> 3.2-bit browser, it looks for a 32-bit JRE. that is why I have a
    >>> 32-bit JRE and 64-bit JDK installed.

    >>
    >> Then how do you explain the fact that other applets and Web Start
    >> applications work fine in this 32-bit browser with a 64-bit JRE?

    >
    > I stand corrected - it appears that only Java Web Start *applications* work
    > with this combination, all other true applets result in an attempt to
    > download and install a 32-bit JRE or complain of missing plug-ins.
    >
    > Why should there be any difference???


    Applets have differed from applications since forever.

    One reason why is that the former are hosted by the browser, the latter by the client machine itself.

    --
    Lew
    Lew, Aug 18, 2011
    #3
  4. Roedy Green

    BGB Guest

    On 8/17/2011 11:18 PM, Knute Johnson wrote:
    > On 8/17/2011 10:21 PM, Qu0ll wrote:
    >> I stand corrected - it appears that only Java Web Start *applications*
    >> work with this combination, all other true applets result in an attempt
    >> to download and install a 32-bit JRE or complain of missing plug-ins.
    >>
    >> Why should there be any difference???

    >
    > I think it is because the Applet runs in the browser plugin and JWS runs
    > the installed JVM.
    >


    yeah. for applets and plugins, they generally run in the same process
    as, or a process managed by, the browser.

    since, canonically, one can't have mixed 32/64 bit processes, then any
    plugins need to match the number of bits. (theoretically at least, one
    could hack around the WoW64 mechanism on Windows to allow mixed-mode
    processes, using some amount of ASM code and similar, but this is likely
    to get very nasty very quickly).

    this actually applies to pretty much any library or DLL, as well as some
    uses of COM objects, ... the result is some amount of redundancy with
    both 32 and 64 bit versions of many libraries being kept around by the
    OS, ...


    this doesn't apply to an externally run JVM, since then the JVM has its
    own process and can use whatever number of bits it wants.
    BGB, Aug 18, 2011
    #4
  5. Roedy Green

    Roedy Green Guest

    On Thu, 18 Aug 2011 15:21:20 +1000, "Qu0ll" <>
    wrote, quoted or indirectly quoted someone who said :

    >
    >I stand corrected - it appears that only Java Web Start *applications* work
    >with this combination, all other true applets result in an attempt to
    >download and install a 32-bit JRE or complain of missing plug-ins.


    With Java Web Start the JVM runs as a separate process. All the
    browser has to do is kick it off. There is no 32-bit/64-bit cross
    calling.

    I have IE9-64/Windows 7/64, but I have not managed to get an applet to
    run. Mind you I have not yet figured out how to get 32 bit to run
    either. I just fiddle around and fiddle around and suddenly it starts
    to work seemingly spontaneously some time later. I have not yet
    worked out a recipe.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com
    The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is,
    the search for a superior moral justification for selfishness.
    ~ John Kenneth Galbraith (born: 1908-10-15 died: 2006-04-29 at age: 97)
    Roedy Green, Sep 1, 2011
    #5
  6. Roedy Green

    Roedy Green Guest

    On Wed, 17 Aug 2011 23:18:58 -0700 (PDT), Lew <>
    wrote, quoted or indirectly quoted someone who said :

    >Applets have differed from applications since forever.
    >
    >One reason why is that the former are hosted by the browser, the latter by the client machine itself.


    With Applets, there is a layer of glue, a DLL that the browser uses to
    run Applets. With Applications and Java Web Start, the JVM runs the
    code directly.
    --
    Roedy Green Canadian Mind Products
    http://mindprod.com
    The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is,
    the search for a superior moral justification for selfishness.
    ~ John Kenneth Galbraith (born: 1908-10-15 died: 2006-04-29 at age: 97)
    Roedy Green, Sep 1, 2011
    #6
  7. Roedy Green

    Arne Vajhøj Guest

    On 9/1/2011 4:23 AM, Roedy Green wrote:
    > On Wed, 17 Aug 2011 23:18:58 -0700 (PDT), Lew<>
    > wrote, quoted or indirectly quoted someone who said :
    >
    >> Applets have differed from applications since forever.
    >>
    >> One reason why is that the former are hosted by the browser, the latter by the client machine itself.

    >
    > With Applets, there is a layer of glue, a DLL that the browser uses to
    > run Applets. With Applications and Java Web Start, the JVM runs the
    > code directly.


    It does not matter - a glue DLL can not switch bitness.

    Arne
    Arne Vajhøj, Sep 2, 2011
    #7
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