From Java to BETA

To be able to access BETA from Java code we have to go through C. From Java to C we use JNI and from C to BETA we use callbacks installed with a specially created DLL.

Besides the Java- and BETA-file we need 4 additional files:

• CDispatch.c - declares the C-functions to be called from Java.
• CDispatch.h - a usual C header file.
• betaCallback.c - installs a callback from BETA and has wrapper functions to call the BETA functions.
• entries.def - lists the entry points in the DLL.

The figure below describes the path of a function call to BETA.

To make this work you have to do the following:

• Compile the lower part of the figure - this is done with the command beta -s 321 betaDispatch
• Compile the upper part of the figure and linking the created DLL from the lower part - this is done with the command:
  cl betaDispatch.lib -Ic:\j2sdk1.4.0_02\include -Ic:\j2sdk1.4.0_02\include\win32 -LD CDispatch.c FeMjolner.dll
• The created DLL's (Mjolner.dll and betaDispatch.dll) is now moved to c:\WINNT\system32

Further details on the Java to C can be found at sun/JNI. And details on the C to BETA part can be found here: using DLL in BETA