...
3. The transport sends the message through a message pipe, which handles quality of service aspects like such as Security and Reliable Messaging. Internally, this pipe is the in-flow and out-flow of Axis2. The ESB can operate in two modes:
...
Quality of Service (QoS) components implement reliable messaging and security implement security for the proxy services, including the Apache implementations of Rampart and Sandesha, which are provided as modules.
...