The Transport module is one of the most important module in the Distributed Service Bus. By nature the Transport module is in charge of exchanging messages between DSB nodes ie this is why this Service Bus is Distributed. This is totally transparent from the user point of view. When a client invokes a service, the service can be located elsewhere in the DSB network, it is up to the DSB Transport module to reach the real service on the right DSB node.While the Petals ESB only provides a transport layer which uses Java NIO to serialize messages between nodes, the DSB goes one step forward and provides a default implementation which uses SOAP/HTTP has transport layer.

Additionally the DSB provides some libraries to develop your own transport layer with your protocol by abstracting things and hiding all the message exchange logic (wait for responses, send acks, etc). The developer has just to focus on how to serialize a DSB message into the protocol of his choice and how to expose server ini order to receive messages. This framework is described in the Transport HOWTOs.