Torsten Curdt’s weblog

I have never been totally convinced of using javascript as the flow language. So I took a closer look into BCEL and Brakes. After I updated Brakes to the current BCEL implementation it seems that everything we need to let java continuations become reality is already in place. The following example is already working:

public final class Runner {
    public static void main(String[] args) throws Exception {
        Classloader loader = new Classloader();
        Class clazz = loader.loadClass("org.apache.bcel.brakes.test.SimpleFlow");
        Flow flow = (Flow) clazz.newInstance();

        Continuation c = null;
        do {
            System.out.println("*** starting flow");
            c = flow.continueWith(c);
            System.out.println("*** returning from flow");
        }
        while(c != null);
    }
}

public final class SimpleFlow extends AbstractFlow {
    public void run() {
        int i = 3;

        String s = new String(""+i);

        System.out.println("STEP1");
        suspend();

        for (int b=0;b<3;b++) {
            System.out.println("" + b + " of " + s);

            System.out.println("STEP2");
            suspend();
        }

        System.out.println("STEP3");
        suspend();

        System.out.println("STEP4");
        suspend();

        System.out.println("end of flow");
    }
}

26. September 2003 | bcel, continuations, java, javaflow