This chapter is from the book
This chapter is from the book
This chapter is from the book
RTSJ Hello World
Working with the TimeSys reference implementation of the RTSJ installed on a Linux system in /usr/local/timesys and with the Sun JDK tools, we show here a step-by-step procedure for creating and running a hello world program for real time.
Hello world doesn't have significant timeliness constraints, so Example 8–1 will just run the standard hello world in a real-time thread.
Example 8–1 RT hello world program
import javax.realtime.*;
public class Hello1 {
public static void main(String [] args){
RealtimeThread rt= new RealtimeThread(){
public void run() {
System.out.println("Hello RT world");
}
};
if(!rt.getScheduler().isFeasible())
System.out.println("Printing hello is not feasible");
else
rt.start();
}
}
The program shown in Example 8–1 is a complete program. Since it prints "Hello RT world" from a real-time thread, that part of its execution can take advantage of priority inheritance and strictly defined, fixed-priority, preemptive scheduling. Those scheduling properties do not make much difference to the output of one short string, but they are there.
To test the program:
If you are developing from the command line, you might use a command like this to compile Hello1:
javac -classpath /usr/local/timesys/rtsj-ri/lib/foundation.jar Hello1.java
If the real-time JVM is on your execution path and the classpath is set to your real-time Java class libraries, a simple command line will run the program:
tjvm Hello1
More likely, you'll need a command line like this:
tjvm -Djava.class.path=/home/dibble/javaprogs/hello1 -Xbootclasspath=/usr/local/timesys/rtsj-ri/lib/foundation.jar Hello1
The output will be:
Hello RT world!