To some degree, that claim is true. I did some contract programming for DEC (later Compaq and now HP) a few years ago using Java as the core for a OS diagnostic system. The program was called CCAT (Compaq Crash Analysis Tool) and it was pretty slick. When my job was finished, CCAT ran on 4 operating systems (Windows NT, NT Alpha, Tru64 Unix, and OpenVMS/AXP). It also supported OpenVMS VAX but didn't run on those systems. During development, we found that we could develop a common Java core that would run on those 4 operating systems. However, we also found some problems with "Write Once, Run Anywhere."

One of our biggest problems was ensuring commonality between Java runtimes. We had to go with the lowest common denominator approach to make sure the code was compatible across all the platforms. Our biggest problem was with OpenVMS/AXP. It was always the last system to get an updated runtime and the performace was glacial. There were also some user interface issues with that OS. Many of the swing.jar components didn't work well on OpenVMS. The system ran great on NT and Tru64 Unix. In the end, we had to "Write Once, Test Everywhere."

I haven't done any Java programming in almost 3 years. If I had the time, I'd love to revisit the language and see how it has improved. I learned Java before I learned C++ and liked Java much better.

CCAT was a fun project. It had a Java core, used CLIPS to store the expert system diagnostic rules, and had a Visual Basic backbone back at corporate. Without violating any nondisclosure agreements, I can briefly say that the system applied expert rules to attempt to diagnose OS crashes on a user's computer. It sent the results of the analysis back to corporate where the problem ticket was automatically logged. The system would reanalyze the crash at corporate because the rulesets would often be more up to date there. If the cause was recognized, it could automatically send the repair instructions (such as a patch) to the user and close the ticket. There were other parts to the system, such as a means for OS experts to write new rules and store them in a database. A VB program that I wrote would automatically generate the CLIPS source code from the database and compile the ruleset for distribution. Like I said, it was a fun project.