Hi, Sorry for spamming, I got your email Id through JNA user group, my scenario is a bit more complex thought of writing to you directly, It would be great if you could give some hints on how to resolve this issue:-

Right now facing problems with Callbacks, we have the following scenario:-

----------------------------------------------------------- C Code

------------------------------------------------------------

typedef struct { WORD structure_size; WORD parameter_code; /* Parameter code number. */ DWORD attributes_size; /* Size of following attributes. */ void *attributes; /* Pointer to attributes. Type of attributes inferred from parameter_code. */ } PARAMETER;

There is a callback which is globally declared in the JNI/C code:-

WORD LIBFUNC API_Callback(HSCANNER, MESSAGE, PARAM1, PARAM2 ); WORD LIBFUNC API_Callback(HSCANNER hengine, MESSAGE message, PARAM1 p1, PARAM2 p2) { WORD returnvalue = 0; engineOutput * myEngineOutput; printf("Message in Callback: %d" , message);

return returnvalue; }

----------------------------------------------------------- JNA MAPPING Code

------------------------------------------------------------ public static class PARAMETER extends com.sun.jna.Structure { /// Allocate a new PARAMETER struct on the heap public PARAMETER () {} /// Cast data at given memory location (pointer + offset) as an existing PARAMETER struct public PARAMETER (com.sun.jna.Pointer pointer, int offset) { super(); useMemory(pointer, offset); read(); } /// Create an instance that shares its memory with another PARAMETER instance public PARAMETER (PARAMETER struct) { this(struct.getPointer(), 0); } public static class ByReference extends PARAMETER implements com.sun.jna.Structure.ByReference { /// Allocate a new PARAMETER.ByRef struct on the heap public ByReference() {} /// Create an instance that shares its memory with another PARAMETER instance public ByReference(PARAMETER struct) { super(struct.getPointer(), 0); } } public static class ByValue extends PARAMETER implements com.sun.jna.Structure.ByValue { /// Allocate a new PARAMETER.ByVal struct on the heap public ByValue() {} /// Create an instance that shares its memory with another PARAMETER instance public ByValue(PARAMETER struct) { super(struct.getPointer(), 0); } } public short structure_size; /// Parameter code number. public short parameter_code; /// Size of following attributes. public com.sun.jna.NativeLong attributes_size; /// Pointer to attributes. Type of attributes inferred from parameter_code. public com.sun.jna.Pointer attributes; // Type this can hold any data } /** * Type of scanning engine callback function.<br> */ public interface CALLBACKTYPE_V1_callback extends com.sun.jna.Callback { /// Original signature : <code>LIBRET CALLBACKTYPE_V1_callback(HSCANNER, MESSAGE, PARAM1, PARAM2_V1)</code> short invoke(com.sun.jna.Pointer HSCANNER11, short MESSAGE12, short PARAM113, com.sun.jna.NativeLong PARAM2_V114); } public class APICallbackImpl implements TestLibrary.CALLBACKTYPE_V1_callback { public short invoke(Pointer HSCANNER11, short MESSAGE12, short PARAM113, NativeLong PARAM2_V114) { return 123;///just for testing } }

Question: How to set the pointer to the callback directly into PARAMETER structure dynamically, we have a void* attributes field which is used, in the current JNI implementation we have a MACRO which actually adds the callback method pointer to this attributes field. But how can we replicate this in JNA implementation? Right now, it is a very critical issue and it is a showstopper for us to proceed further, we browsed over and over again, but couldn’t find anything useful.

And also if possible, if you could give us how to debug JNA/C code through eclipse or someother tool it would be helpful.

Thanks in advance! J

Regards, JK M: 9845955933 "If you are good at something, never do it for free!"

http://www.mindtree.com/email/disclaimer.html