Lifecycle integration

Initialise and teardown nodes

Introduction

The goal is to provide a facility for nodes in the SEP to receive initialise and teardown notifications.

Nodes may want to carry out one-off initialisation before processing events, or release resources if the SEP has completed processing and will receive no more events. Fluxtion provides two annotations that a node can a mark a method with to join the lifecycle callback set.

Annotation	Behaviour
@Initialise	Invoked before any events are processed. Initialisation methods are invoked in topological order.
@TearDown	Invoked after all events have been processed by the SEP. Teardown methods are invoked in reverse topological order.

Example

In this example we annotate several classes in a graph with various @Initialise and @TeardDown annotations. The generated SEP implements the lifecycle method callbacks in the init and teardown methods defined in the Lifecycle interface.

The code for the example is located here.

Node classes:

public class CleanListener {
//omitted code for clarity
    @Initialise
    public void init() {}
}

public class DirtyListener {
//omitted code for clarity   
    @TearDown
    public void tearDown() {}
}

public class DirtyCleanCombiner {
//omitted code for clarity   
    private final Object parent1;
    private final Object parent2;
        
    @Initialise
    public void init(){}
    
    @TearDown
    public void tearDown(){}    
}

Generated SEP

The two methods of interest in the SEP are the init and tearDown methods.

Note the generated SEP does not call the lifecycle methods init and tearDown that is the repsonsibility of the application code using the SEP.

public class SampleProcessor implements EventHandler, BatchHandler, Lifecycle {

  //Node declarations
  private final ConditioningHandler conditioningHandler_1 = new ConditioningHandler();
  private final CleanListener cleanListener_3 = new CleanListener(conditioningHandler_1);
  private final DirtyCleanCombiner dirtyCleanCombiner_7 =
      new DirtyCleanCombiner(cleanListener_3, cleanListener_3);
  private final DirtyListener dirtyListener_5 = new DirtyListener(conditioningHandler_1);

  //code omitted for clarity

  @Override
  public void init() {
    conditioningHandler_1.init();
    cleanListener_3.init();
    dirtyCleanCombiner_7.init();
  }

  @Override
  public void tearDown() {
    dirtyListener_5.tearDown();
    dirtyCleanCombiner_7.tearDown();
    conditioningHandler_1.tearDown();
  }

}

Generated png

The graphical representation of this execution graph as generated by Fluxtion ESC:

Example SEP demonstrating init and teardown lifecycle