Access to SOAP-Header objects during mapping

Hi!

Is there any possibility to get access of SOAP-Header during a mapping? Our scenario: We're receiving a message via proxy from another 640. Now we want to get the real sender of the message (SOAP-Header -> RunTime -> SAP:User) to confirm the transfered data.

More detailed:

A sender requests via a proxy call data from our system. The connection is confirmed due to the settings of the used http-connection. But to be sure he is asking for data related to himself and not to another customer, we have to check the user from the SOAP and don't want to use a user transfered in the payload.

Any idea?!

Kind regards,

Klaus