call LabVIEW DLL in Java (JNI)

[ltok]

Hi,

I would like to know how to call LabVIEW DLL in Java (JNI).

I have searched in the forum and some mentioned that I need to have a wrapper DLL that exports the "JNI-style" names and calls the names exported from the LV-built DLL. I do not know what does this means??

I want to use JNI to control GPIB so I want to build 488.2 or VISA vis into DLL which I can call in JNI. Could anyone guide me in doing this?? What are the steps and how to do it??

JNI and LabVIEW

http://forums.ni.com/ni/board/message?board.id=250&message.id=27384&requireLogin=False

Thank you & Regards

Lee

[ltok]

More things to add...

I have found websites that mention that I need to have a header which is generated by JNI to be included in the LabVIEW DLL header so that JNI can use this LabVIEW DLL in JNI. How do I do that??

Both links below have information on calling DLL in Java (JNI).

Calling Native C/C++ code (in a DLL) from Java using JNI

http://kbalertz.com/222092/Native-Using.aspx

Java Native Interface: Programmer's Guide and Specification

http://java.sun.com/docs/books/jni/

I am using LabVIEW 8.20 and found that I could not add in external header when building DLL in DLL properties. I can only add additional LabVIEW headers but not other external headers. Does that mean that I need to build the JNI header and call it in my vi before I build this vi into DLL to include JNI header in my DLL header?? Could anyone advise me on this??

Thank you & Regards

Lee

[kaêm]

Hi,

I don't have particular information about how to make calls from Java to LV DLL, but I'll describe
you how to make a wrapper DLL.

So, beside the LV DLL, you'll need another DLL that works as an interface to the LV DLL. In this
DLL, you'll have to write a function that matches every function in your LV DLL. I'll give some code
sample in C.

void /*some calling conventions and JNI specific stuff*/ loadLVLib()
{
    // load the LV library in to memory. The calls are different for each platform (and compiler),
    // but in VC++ for example, this is done with the LoadLibrary() function.
    // This will give you handle to the library
}

void /*Again some calling convections and JNI stuff is required*/ doDAQOperation()
{
    // use the handle to make a call to LV function. You can do this with GetProcAddress()
    // in VC++, there's also other means to do this.
}

void /*JNI etc stuff*/ releaseLVLib()
{
    // in VC++, one would use FreeLibrary() function in here.
}

I think this should give you an idea of the wrapper. If you have more questions about this,
post them and I'll try to give you an answer.