Apache Axis2 provides session handling capability using 4 session scopes; request, soapsession, transport and application. I have already blogged about application scope a few months ago.
Axis2 transportsession uses transport level session management techniques to manage sessions of a Web service. Life time of a session is governed by the underlined transport, not by Axis2 itself. If a service is deployed in a transportsession scope, then, there will be service instances for each of the transport session.
You can read my recent Knowledge base post on how to manage sessions with transport session scope here at wso2 oxygen tank.