In order to receive messages that published under a certain topic the toolbox must first have subscribed to the topic. Subscription and unsubscription can be made in two different ways:
Implicit subscription
When the application is started an automatic subscription is made to the topics of all the XML Message In objects of the application. Similarly, when the application is stopped an automatic unsubscription is made to the topics of all the XML Message Out objects in the application. Implicit subscription is always activated.
Explicit subscription.
A topic is subscribed to using the function subscribe(aTopic). Similarly a topic is unsubscribed to using the function unsubscribe(aTopic).