Q: | 64bit JVM + 32bit COM DLL |

Chris Gao
  • Chris Gao

    Chris Gao - 2009-12-08

    Dear all,

    I have a question about JACOB. It is about calling 32bit COM object (packed in a dll file) from 64bit JVM on a 64bit Windows 7 computer.

    I have a Java application running (currently) on a 32bit JVM, which in turn, installed on a 32bit Windows 7 OS computer. This application calls a third-party image viewer through COM interface provided by the image viewer's vendor.

    As we can foresee, some users of my application may move to 64bit environment, say 64bit windows 7 with 64bit JVM installed. Certainly, the JACOB library already provide 64bit support in the latest version. However, the vendor of the image viewer may not ready to do so for their product yet. Their viewer application can be installed and run on the 64bit OS because of the WOW64 subsystem.

    However, what I am not sure is that can I still control the viewer through ordinary 32bit COM object (packed in a DLL file) provided by the image viewer's vendor in the new 64bit environment through JACOB?

    Please give me some information on this.   :-)

    Many thanks,

    Best regards,


  • Chris Gao

    Chris Gao - 2009-12-08

    Just to make it more clear: the reason that I post the question above instead of try it out by myself is because I don't have a 64bit computer to test.  :-)

  • clay_shooter

    clay_shooter - 2009-12-25

    Jacob , by default, picks the 32/64 bit dll that corresponds to the "bitness" of the VM.  Jacob lets you override this decision  So in theory, you may be able to specify the 32 bit dll to talk 32 bit to  the 32 bit application.

    You'll have to try it.

  • Anonymous - 2010-04-26

    How do you specify the 32-bit dll to talk to the 32-bit application?

  • Geln Yang

    Geln Yang - 2013-02-20

    chrisgao , do you have solution now?

  • clay_shooter

    clay_shooter - 2013-07-25

    Did you try overriding the dll selection through properties. I believe this is (somewhat) documented.


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