...
If the above feature is not included in your product by default, you install it using the instructions given in section, Feature Management.
Modules use handlers to engage in different message flows at defined phases. You can observe the handlers invoked in each phase of each flow in real time. For example, the Apache/Rampart module defines handlers in the security phase of each flow, which handles the security aspects of the messages that are transferred through these flows. Therefore, if the Rampart module is engaged, you can see the Apache/Rampart handlers in the message flows in real time.
...