How To Set up web service session management and best practices (Doc ID 1266239.1)
If you are interested in using inbound web services session management headers, details such as the correct URL to use, authentication type , examples of SOAP Headers and where to look for the session token in the SOAP Response can all be found at :
How To Set up web service session management and best practices (Doc ID 1266239.1)
Please also check document Use Siebel Authorization Stateless Session Management for HIGH load inbound web service integrations (Doc ID 795552.1)
for a high level suggestion on how to deal with the ever changing tokens at the client (middleware) side.