Re: RPG Handshake with java program and capture of "exception Java error"

Hello Jorge,

I have been told that in the case of an exception Java type we have
to manipulate the Java exception in a different way Is it possible to
catch that Java exception error in RPG and how would you recomend to
do it?

Under the covers, the RPG program is calling the JNI API to run your Java routine. After each JNI call, it has to call a JNI routine called ExceptionCheck (or ExceptionOccurred() one of the two) to determine if the call succeeded or failed, and then it retrieves details of the exception, and ExceptionClear() to clear the exception. The code to do all of this is generated by the compiler.

When an exception occurs, the generated code then sends an *ESCAPE message to the RPG program so that your code can detect that something failed. The important parts of the exception are sent as MSGDTA in that *ESCAPE message.

The calling RPG program can use the MONITOR opcode to catch the exception, and can then retrieve the message with QMHRCVPM read the MSGDTA to find out information about the exception.

If that support isn't sufficient for your needs, your options are:

a) Change the Java routine to NOT throw an exception, but instead, return error information via parameters/return values.

-or-

b) Call the JNI routines directly instead of using RPG's support for calling Java. Then you could control the exception handling yourself.

-or-

c) File a DCR with IBM and ask them to change the way they handle exceptions to make more information available to the RPG program directly (instead of going through the message) and hope they do it. (But this would likely take a long time to happen, if they even agreed to do it.)


So I guess my question is... what's wrong with using RPG's MONITOR op-code? From your message, you already knew it was a possibility, but discounted it for some reason. What is that reason? Why not use MONITOR?