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package example;
import com.amazonaws.services.simpleworkflow.model.WorkflowExecution;
import com.bazaarvoice.sswf.HeartbeatCallback;
import com.bazaarvoice.sswf.WorkflowDefinition;
import com.bazaarvoice.sswf.model.DefinedStep;
import com.bazaarvoice.sswf.model.ScheduledStep;
import com.bazaarvoice.sswf.model.SleepStep;
import com.bazaarvoice.sswf.model.StepInput;
import com.bazaarvoice.sswf.model.history.StepsHistory;
import com.bazaarvoice.sswf.model.result.Cancelled;
import com.bazaarvoice.sswf.model.result.InProgress;
import com.bazaarvoice.sswf.model.result.StepResult;
import com.bazaarvoice.sswf.model.result.Success;
import com.bazaarvoice.sswf.model.result.Wait;
import com.bazaarvoice.sswf.service.WorkflowManagement;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
public class ExampleWorkflowDefinition implements WorkflowDefinition {
private WorkflowManagement workflowManagement;
private ExampleSignalHandler exampleSignalHandler;
// I'm implementing a little state machine here to demonstrate the desired pattern of checking invariants first,
// returning InProgress until they are done, and returning Success if and only if all invariants are met.
// This results in a workflow whose steps are idempotent, and which is therefore restartable (and much less headachey).
private static Map state = new ConcurrentHashMap<>();
public ExampleWorkflowDefinition(final WorkflowManagement workflowManagement, final ExampleSignalHandler exampleSignalHandler) {
this.workflowManagement = workflowManagement;
this.exampleSignalHandler = exampleSignalHandler;
}
@Override public List> workflow(final ExampleWorkflowInput exampleWorkflowInput) {
return Arrays.asList(
new DefinedStep<>(ExampleWorkflowSteps.EXTRACT_STEP),
new DefinedStep<>(ExampleWorkflowSteps.TRANSFORM_STEP, "format1->format2"),
new DefinedStep<>(ExampleWorkflowSteps.TRANSFORM_STEP, "format2->format3"),
new SleepStep<>(60),
new DefinedStep<>(ExampleWorkflowSteps.TIMEOUT_ONCE_STEP),
new DefinedStep<>(ExampleWorkflowSteps.LOAD_STEP)
);
}
@Override
public void onFail(final String workflow,
final String run,
final ExampleWorkflowInput exampleWorkflowInput,
final StepsHistory history,
final String message) {
System.out.println("[" + workflow + "/" + run + "] Workflow(" + exampleWorkflowInput.getName() + ") Failed!!! " + message);
}
@Override
public void onFinish(final String workflow,
final String run,
final ExampleWorkflowInput exampleWorkflowInput,
final StepsHistory history,
final String message) {
System.out.println("[" + workflow + "/" + run + "] Workflow(" + exampleWorkflowInput.getName() + ") Finished!!! " + message);
}
@Override
public void onCancel(final String workflowId, final String runId, final ExampleWorkflowInput exampleWorkflowInput, final StepsHistory history, final String message) {
System.out.println("[" + workflowId + "/" + runId + "] Workflow(" + exampleWorkflowInput.getName() + ") Cancelled!!! " + message);
}
@Override public StepResult act(final ExampleWorkflowSteps step,
final ExampleWorkflowInput exampleWorkflowInput,
final StepInput stepInput,
final HeartbeatCallback heartbeatCallback,
final WorkflowExecution workflowExecution) {
switch (step) {
case EXTRACT_STEP:
for (int i = 0; i < 10; i++) {
// Note we're not required to cancel if this is true, it's just a request.
final boolean cancelRequested = heartbeatCallback.checkIn("just an example heartbeat checkin");
System.out.println("Cancellation requested: " + cancelRequested);
if (cancelRequested) {
return new Cancelled("We got cancelled");
}
try {
Thread.sleep(500);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
if (!Objects.equals(state.get(exampleWorkflowInput.getName()), "extract finished")) {
state.put(exampleWorkflowInput.getName(), "extract finished");
return new InProgress("started extract");
}
return new Success("Extract is done.");
case TRANSFORM_STEP:
if (!Objects.equals(state.get(exampleWorkflowInput.getName()), "transform finished (" + stepInput.stepInputString() + ")")) {
state.put(exampleWorkflowInput.getName(), "transform finished (" + stepInput.stepInputString() + ")");
return new InProgress("transform started (" + stepInput.stepInputString() + ")");
}
return new Success("Nothing to do!");
case LOAD_STEP:
final String signal1 = workflowManagement.generateSignal(workflowExecution.getWorkflowId(), workflowExecution.getRunId());
exampleSignalHandler.addSignal(signal1);
final String signal2 = workflowManagement.generateSignal(workflowExecution.getWorkflowId(), workflowExecution.getRunId());
exampleSignalHandler.addSignal(signal2);
return new Wait(60, signal1, signal2);
case TIMEOUT_ONCE_STEP:
System.out.println("resume: " + stepInput.resumeProgress());
if (!Objects.equals(state.get(exampleWorkflowInput.getName()), "timeout_once finished")) {
state.put(exampleWorkflowInput.getName(), "timeout_once finished");
heartbeatCallback.checkIn("[95] of [100]");
throw new RuntimeException("Forcing a timeout");
}
return new Success("timeout_once finished. Resumed from " + stepInput.resumeProgress());
default:
throw new IllegalStateException("Unexpected step enum" + step);
}
}
}
