I'm still convinced Java is awesome and that embedded programmers using C++ would benefit heavily from switching over to it.
I first encountered Java in 1996. I was working for a company that built satellite telemetry equipment. Parts of this were real-time/embedded-mostly VME boards running VxWorks. But other parts of the data post-processing were done on Sun workstations. I became interested in the language when, pulled aside from my embedded programming responsibilities for several months, I was enjoined to help write some workstation software in Java. It was love at first compile.
I loved that its basic syntax was very like C's, but that its creators had addressed many of that languages inconsistencies and pitfalls. I was also impressed at how much faster it was to program in Java than C++, a language I'd tried to love without success. Java also had some cool features for embedded programmers-things like fixed-size integers, a portable binary format, guaranteed protection from memory leaks, and built-in support for threads and synchronization (no more porting your embedded code from one RTOS API to yet another).
The only problem was that I loved embedded programming more-I still do. So I've been on a five-year odyssey of hope, wanting to use Java in my embedded programming, but never having the opportunity to do anything more than experiment. I'm still convinced the language is awesome and that embedded programmers using C++ would benefit heavily from switching over to it. However, the priority in our field is always shipping a product vs. trying some new language or tool to make the process easier.
To find out where things stand with embedded Java today, I organized and moderated a panel called “Is Java Ready for Embedded Use?” at the Embedded Systems Conference in Boston in September. The panel consisted of two real-time Java gurus and four embedded programmers who'd recently used Java technologies from Wind River, NewMonics, aJile, and other vendors. Here's what I and the other attendees learned.
The most important thing we learned was that people are now building real systems (and even shipping some of them!) with Java. Of course, the Real-Time Specification for Java (RTSJ) is still several months away from having a complete reference implementation (RI) and testing compatibility kit (TCK), so today's embedded Java users are mostly from the “no-real-time” side of the house.
A common current use for Java is as a user interface engine; the real-time and device-specific stuff is still being done in C. A Java Virtual Machine is simply added to the system for executing complex and, perhaps, field-upgradable, user interface threads. The big advantages are that: (1) any competent Java programmer can be enlisted to produce that part of the embedded software, and (2) feedback from marketing and target customers can be sought and incorporated long before the actual hardware is complete. Wind River says that about 10% of its RTOS customers are also licensing a JVM from them and using it for such purposes.
Another option is to base your system design on a Java processor and write all of the firmware in Java. The processors from aJile Systems, in particular, support many of the features recommended by the draft RTSJ spec. This means that real-time programming in Java is available today, in quantity. And aJile has already stated they'll conform their technology to the final spec, as soon as the RI and TCK are available.
It should be extremely interesting to watch the embedded Java space over the next couple of years and to see how an increasing number of users will take advantage of its many great features.