Aggregator Vs Executors.

Here you can see all the sub sets of processes are connected with the aggregator. Each sub process wants the aggregator to get run. That means the data that executor wants to execute the sub process, is located at the aggregator. If some executor is not linked with the aggregator, it is not configured in the framework. You can see the executor-introduction or the real implementation of the example to learn more about the executors.