How to interchange data between Java Program and C++ Program

How to interchange data between Java Program and C++ Program

I constructed a java program using netbeans IDE that has ability to
connect with a respective DLL; I want to connect and interchange data
between my java program(.jar) and VSC++ program(.exe) through DLLs.JNI
uses single Dll to invoke C/C++ function in native manner,In order to
increase the efficiency I tried to connect and interchange primitive data
types between Java program and C++ program using that DLL(JNI
implemented).
Unfortunately C++ program cannot obtain data values that has been changed
by Java Program.Fot example - If I declare a global int variable in
DLL,java program can catch that int variable and can update it but If I
run my C++ program(exe) loading same DLL simultaneously it cannot receive
the updated value of that int variable declared in the DLL.
Therefore I need a solution to share/Interchange at least primitive data
and their respective values between a JAVA and C++ Program using JNI (in
spite of date transferring through Sockets).JAVA TO C/C++ & C/C++ to JAVA
using DLLs.
PLEASE HELP ME!! THANK YOU