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Jon: I recently (and amazingly) seriously considered using JNI in a real project to call back from ILE/RPG into native java applications. The project was canned (in favor or WebFacing(!)) however, and so I cannot justify spending any more time on JNI right now. The situation that prompted use of JNI was unique in that the 'mandated' architecture for a browser-based application involved using ILE/RPG on the iSeries for all back-end database access and business logic (due to a plentiful supply of in-house RPG skills). On paper, JNI would have given us a low-level tight coupling between an implemented 'adapter' (perhaps conforming to the JCA interface for portability across platforms) and RPG procedures in the mandated RPG 'data access layer'. This would give us good performance and fine-grained access, with the added benefit of some exposure of Java to the RPG programmers. (We considered PCML to be too slow for fine-grained access. JDBC stored procedures were considered to be too cumbersome as they would mandate use of bound programs for every possible entry point to the 'RPG layer'.) Anyway, the idea behind using JNI was that the Java 'Data Access Object/Bean' is constructed in the application server and a java native method calls directly into to the relevant RPG Procedure. The RPG procedure now has a handle to the object and calls the setters in the DAO by using the %THIS built-in-function and assigning the data from the database, and maybe a bunch of other procedural stuff. On return from the RPG procedure, the java DAO is now fully populated with data and can be accessed by the Session Bean. You mention that you have used the method call support and that you are aware of the pitfalls. I am aware of the garbage collection issue, the use of static/global variables in the RPG as a pitfall, and the issue of translation of data when not calling via methods. What other pitfalls are there? Thanks in advance. Chris Jewell -----Original Message----- From: java400-l-admin@midrange.com [mailto:java400-l-admin@midrange.com]On Behalf Of Jon Paris Sent: Wednesday, May 29, 2002 3:16 PM To: java400-l@midrange.com Subject: Calling Java from RPG/COBOL I'd like to hear from those of you with more "real world" experience than me of the pros and cons of different methods of invoking a Java app from RPG and/or COBOL. One specific item that I'm interested in is parameter passing - and returning results from the Java code. I've used the new RPG method call support and am aware of the pitfalls there, but that is not applicable to COBOL and JNI is just to darned ugly to want to consider unless the alternative is a lobotomy! Jon Paris Partner400 _______________________________________________ This is the Java Programming on and around the iSeries / AS400 (JAVA400-L) mailing list To post a message email: JAVA400-L@midrange.com To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/cgi-bin/listinfo/java400-l or email: JAVA400-L-request@midrange.com Before posting, please take a moment to review the archives at http://archive.midrange.com/java400-l.
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